Zoladex (goserelin)

What is Zoladex?

Zoladex is a brand-name prescription drug that’s FDA-approved to treat the following:

• Prostate cancer that’s locally confined. Prostate cancer starts in the prostate gland, which is located between the penis and bladder. “Locally confined” means that the cancer hasn’t spread past the prostate. Zoladex is used with another drug called flutamide to treat this type of prostate cancer before and during radiation therapy.
• Advanced prostate cancer. “Advanced” means that the cancer has spread from the prostate gland to other parts of the body. Zoladex is used as a palliative treatment to help ease symptoms such as bone pain and trouble urinating. The medication also works to improve the quality of life for people with advanced prostate cancer. Zoladex isn’t a cure for the disease.
• Endometriosis. With this condition, tissue grows abnormally outside the uterus (womb).
• Abnormal uterine bleeding. With this condition, you menstruate (bleed) at times other than during your normal menstrual cycle (period). Zoladex is used to thin the lining of your uterus before an endometrial ablation. This is a procedure in which the lining of your uterus is removed.
• Advanced breast cancer. This kind of cancer begins in the breast and then spreads to other parts of the body. Zoladex is used as a palliative treatment to ease symptoms such as bone pain. The drug also works to improve the quality of life for females* with advanced breast cancer who are premenopausal (haven’t gone through menopause) or perimenopausal (the stage right before menopause). Zoladex isn’t a cure for advanced breast cancer.

* Use of the term “female” within this article refers to a person’s sex assigned at birth.

Drug details

Zoladex contains the drug goserelin, which belongs to a class of medications called gonadotropin releasing hormone (GnRH) agonists. (A medication class is a group of drugs that work in a similar way.)

Zoladex is a type of hormone therapy that works to lower levels of sex hormones such as testosterone and estrogen.

Zoladex comes as an implant that’s inserted subcutaneously (under the skin), usually around your belly button. You’ll go to your doctor’s office or a clinic where a healthcare professional will perform the procedure.

One 3.6-milligram (mg) Zoladex implant will last for 28 days. One 10.8-mg Zoladex implant will last for 12 weeks. After that, your doctor may want you to have another implant inserted to continue treatment.

Effectiveness

A clinical study looked at people with advanced breast cancer to see how well Zoladex helped slow tumor growth. Zoladex was compared with oophorectomy (surgery to remove one or both ovaries). The tumor responded, meaning that it shrank or stopped growing, in 22% of people who received Zoladex. In comparison, the tumor responded in only 12% of people who had an oophorectomy.

For more about the effectiveness of Zoladex in treating other conditions, see the “Zoladex uses” section below.

Zoladex generic

Zoladex is available only as a brand-name medication. It’s not currently available in generic form.

A generic drug is an exact copy of the active drug in a brand-name medication. The generic is considered to be just as safe and effective as the original drug. Generics also tend to cost less than brand-name drugs.

Zoladex contains one active drug ingredient: goserelin. This means goserelin is the ingredient that makes Zoladex work.

Zoladex side effects

Zoladex can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Zoladex. These lists don’t include all possible side effects.

For more information on the possible side effects of Zoladex, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs they have approved. If you would like to report to the FDA a side effect you’ve had with Zoladex, you can do so through MedWatch.

Mild side effects when used to treat prostate cancer

Mild side effects of Zoladex that are more common* when the drug is used to treat prostate cancer can include:

• hot flashes (also called hot flushes)
• impotence (not being able to have and keep an erection)
• trouble urinating

Mild side effects of Zoladex that are less common** when the drug is used to treat prostate cancer can include:

• bloating and fluid retention (buildup)
• infections, such as the common cold
• lung conditions, such as chronic obstructive pulmonary disease (COPD)
• fatigue (lack of energy)
• pain
• dizziness
• insomnia (trouble falling or staying asleep)
• loss of appetite
• nausea
• rash
• sweating

* occurred in more than 10% of people in clinical studies
** occurred in less than 10% of people in clinical studies

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

Mild side effects when used to treat endometriosis or breast cancer

Mild side effects of Zoladex that are more common* when the drug is used to treat endometriosis (a condition in which tissue grows abnormally outside the uterus) or breast cancer can include:

• acne
• bloating
• change in breast size
• sexual side effects, such as a sex drive that’s higher or lower than usual, or pain during sex
• headache
• rash with white scales
• hot flashes
• vaginitis (irritation and swelling of the vagina)
• insomnia
• mood changes
• pain
• pelvic pain (pain between your belly button and groin)
• sweating
• weakness
• nausea

Mild side effects of Zoladex that are less common** when the drug is used to treat endometriosis or breast cancer can include:

• back pain
• breast pain
• dizziness
• hair loss
• leg cramps
• muscle pain or stiffness
• stomach pain
• hirsutism (unusual hair growth on the face or body)
• increase in appetite or weight gain
• upper respiratory infection, such as the common cold
• voice changes, such as a deeper voice

* occurred in more than 10% of people in clinical studies
** occurred in less than 10% of people in clinical studies

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

Serious side effects

Serious side effects from Zoladex aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

• Depression. Symptoms can include:
  • trouble concentrating or making decisions
  • feeling hopeless or pessimistic
  • loss of energy or feeling “slowed down”
  • loss of interest in hobbies or activities
• High blood sugar. Symptoms can include:
  • fatigue
  • headache
  • increased thirst
  • trouble concentrating
• Hypercalcemia (high level of calcium in your blood). Symptoms can include:
  • belly pain
  • constipation
  • extreme thirst
  • frequent urination
  • feeling irritable (easily frustrated or upset)
  • trouble remembering things
• Long QT syndrome (a condition in which your heartbeat is uneven). Symptoms can include:
  • fainting
  • irregular heartbeat
  • seizures
• Serious cardiovascular (heart and blood vessel) conditions, including heart attack and stroke. Symptoms can include:
  • anxiety
  • chest pain
  • confusion
  • dizziness
  • fainting
  • shortness of breath
  • sudden numbness or weakness of your arm, face, or leg (especially on just one side of your body)
• Spinal cord compression (increased pressure on your spinal cord). Symptoms may include:
  • burning pain that spreads to your arms, buttocks, or legs
  • cramping, numbness, or weakness in your arms or legs
  • loss of feeling in your feet
  • pain and stiffness in your back or neck

Other serious side effects, explained in more detail below in “Side effect details,” include:

• allergic reaction
• tumor flare (growth of a tumor for a very short time)
• injection site injury in the spot where Zoladex is inserted

Side effect details

You may wonder how often certain side effects occur with this drug.Here’s some detail on several of the side effects this drug may cause.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Zoladex. In one study, about 1% of people who received Zoladex had an allergic reaction. Zoladex wasn’t compared with a different medication or a placebo (treatment with no active drug).

Symptoms of a mild allergic reaction can include:

• skin rash
• itchiness
• flushing (warmth and redness or deepening of color in your skin)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

• swelling under your skin, typically in your eyelids, lips, hands, or feet
• swelling of your tongue, mouth, or throat
• trouble breathing

Call your doctor right away if you have a severe allergic reaction to Zoladex. Call 911 if your symptoms feel life threatening or if you think you’re having a medical emergency.

Weight gain

Weight gain is possible with Zoladex. In a clinical study, about 3% of people who received Zoladex reported gaining weight. Researchers compared Zoladex with danazol, another drug used for endometriosis. Of the people who took danazol, 23% reported weight gain.

Weight gain isn’t common with Zoladex, but some people can have issues with weight control while taking the drug. If you’re concerned about weight gain while taking Zoladex, talk with your doctor. They may be able to suggest helpful ways to manage your weight.

Tumor flare

Zoladex causes a very short-term increase in hormone levels during the first few weeks of treatment. In people with prostate or breast cancer, this increase may cause the tumor (mass of cancerous tissue) to grow for a very short time before Zoladex takes full effect. This is known as a tumor flare.

In a clinical study, Zoladex was compared to oophorectomy (surgery to remove one or both ovaries). Of the people who took Zoladex, 23% had a tumor flare, compared with just 4% of people who had an oophorectomy.

You usually won’t notice a tumor flare. In rare cases, a tumor flare can cause symptoms of breast or prostate cancer to get worse. A tumor flare typically goes away on its own, but it can become bothersome or serious in some people.

Serious signs and symptoms of tumor flare can include:

• blood in your urine
• trouble urinating
• not being able to urinate
• new or worsening bone pain
• weakness or loss of feeling in your legs

If you notice any of these signs and symptoms, call your doctor right away. They can recommend the best treatment for you.

Injection site injury

Because Zoladex is inserted under the skin, there’s a small risk for injury at the injection site (the area where Zoladex is placed). In clinical studies, about 1% to 6% of people who received Zoladex reported having an injection site reaction. Zoladex wasn’t compared with a different implant or placebo in these studies.

Symptoms of an injection site injury include:

• hematoma (an area of blood that collects under the skin outside of blood vessels)
• hemorrhage (severe bleeding)
• pain or irritation at the injection site

It’s also possible to have more serious symptoms of an injection site injury. So if you have any of the following after receiving your Zoladex implant, tell your doctor right away:

• dizziness
• low blood pressure
• shortness of breath
• stomach pain
• stomach swelling and bloating

Your doctor can recommend the best treatment for you.

Alternatives to Zoladex

Other drugs are available that can treat your condition. Some may be a better fit for you than others. If you’re interested in finding an alternative to Zoladex, talk with your doctor. They can tell you about other medications that may work well for you.

Note: Some of the drugs listed here are used off-label to treat these specific conditions. Off-label use is when a drug that’s approved to treat one condition is used to treat a different condition.

Alternatives for the palliative treatment of advanced breast cancer

Examples of other drugs that may be used for the palliative treatment of advanced breast cancer include:

• anastrozole (Arimidex)
• doxorubicin (Doxil)
• exemestane (Aromasin)
• letrozole (Femara)
• tamoxifen (Soltamox)
• trastuzumab (Herceptin)

Alternatives for endometriosis

Examples of other drugs that may be used to treat endometriosis include:

• birth control pills
  • combined oral contraceptives, such as drospirenone/ethinyl estradiol (Yaz)
  • progestin-only pills, such as norethindrone
• danazol
• leuprolide acetate (Lupron Depot)
• medroxyprogesterone (Depo-Provera)
• nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin)

Alternatives for prostate cancer

Examples of other drugs that may be used to treat prostate cancer include:

• apalutamide (Erleada)
• darolutamide (Nubeqa)
• enzalutamide (Xtandi)

Alternatives for the palliative treatment of advanced prostate cancer

Examples of other drugs that may be used to treat advanced prostate cancer include:

• abiraterone acetate (Zytiga, Yonsa)
• bicalutamide (Casodex)
• degarelix (Firmagon)
• histrelin acetate (Supprelin LA)
• leuprolide acetate (Lupron Depot)
• nilutamide (Nilandron)
• triptorelin (Trelstar)

Alternatives for uterine bleeding

Examples of other drugs that may be used to treat uterine bleeding include:

• combined oral contraceptives, such as Yaz
• conjugated equine estrogen (Premarin)
• danazol
• leuprolide acetate (Lupron Depot)
• medroxyprogesterone acetate (Provera)
• nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin)

Zoladex vs. Lupron Depot

You may wonder how Zoladex compares with other medications that are prescribed for similar uses. Here we look at how Zoladex and Lupron Depot are alike and different.

Ingredients

Zoladex contains the active drug goserelin. Lupron Depot contains the active drug leuprolide.

Although they contain different active drugs, Zoladex and Lupron Depot work in the same way. They both block production of certain hormones, including estrogen and testosterone. Both medications lower levels of these hormones in the blood.

Uses

The Food and Drug Administration (FDA) has approved both Zoladex and Lupron Depot to treat advanced prostate cancer. This type of cancer starts in the prostate gland, which is located between the penis and bladder. “Advanced” means that the cancer has spread from the prostate gland to other parts of the body. Zoladex and Lupron Depot are used as palliative treatments to help ease symptoms such as bone pain and trouble urinating. The medication also works to improve the quality of life for people with advanced prostate cancer. Zoladex and Lupron Depot aren’t cures for the disease.

Lupron Depot and Zoladex are also FDA-approved to treat:

• Endometriosis. With this condition, tissue grows abnormally outside the uterus (womb).

In addition, Zoladex is FDA-approved to treat:

• Prostate cancer that’s locally confined. “Locally confined” means that the cancer hasn’t spread past the prostate. Zoladex is used with another drug called flutamide to treat this type of prostate cancer before and during radiation therapy.
• Abnormal uterine bleeding. With this condition, you menstruate (bleed) at times other than during your normal menstrual cycle (period). Zoladex is used to thin the lining of your uterus before an endometrial ablation. This is a procedure in which the lining of your uterus is removed.
• Advanced breast cancer. This kind of cancer begins in the breast and then spreads to other parts of the body. Zoladex is used as a palliative treatment to help ease symptoms such as bone pain. The drug also works to improve the quality of life for females* with advanced breast cancer who are premenopausal (haven’t gone through menopause) or perimenopausal (the stage right before menopause). Zoladex isn’t a cure for advanced breast cancer.

Lupron Depot is also approved to treat uterine leiomyomata (fibroids, which are noncancerous growths). Specifically, Lupron Depot is used along with iron therapy to help improve anemia (low iron in the blood) in people with this condition.

* Use of the term “female” within this article refers to a person’s sex assigned at birth.

Drug forms and administration

Both Zoladex and Lupron Depot must be given by a healthcare professional, but the medications come in different forms.

Zoladex comes as an implant that’s inserted subcutaneously (under the skin), usually around your belly button. You’ll go to your doctor’s office or a clinic where a healthcare professional will perform the procedure.

One 3.6-milligram (mg) Zoladex implant will last for 28 days. One 10.8-mg Zoladex implant will last for 12 weeks. After that, your doctor may want you to have another implant inserted to continue treatment.

Lupron Depot comes as a suspension (liquid). A healthcare professional gives it as an injection into the muscle (intramuscular) of your buttocks, shoulder, or thigh. You may receive a Lupron Depot injection every 1, 3, 4, or 6 months.

Side effects and risks

Although Zoladex and Lupron Depot contain different drugs, they work in similar ways. Therefore, these medications can cause some similar and some different side effects. Below are examples of these side effects.

Mild side effects

These lists contain examples of mild side effects that can occur when treating prostate cancer with Zoladex, with Lupron Depot, or with both drugs (when taken individually).

• Can occur with Zoladex:
  • loss of appetite
  • rash
• Can occur with Lupron Depot:
  • constipation
  • headache
  • weakness
• Can occur with both Zoladex and Lupron Depot:
  • aches and pains
  • bloating and fluid retention (buildup)
  • impotence (not being able to have and keep an erection)
  • hot flashes (also called hot flushes)
  • shrunken testicles*
  • insomnia (trouble falling or staying asleep)
  • trouble urinating
  • infections, such as the common cold
  • lung conditions
  • fatigue (lack of energy)
  • injection site reactions (pain, redness, or swelling at the injection site)
  • nausea

* This isn’t listed as a side effect of Zoladex, but it is an expected side effect of medications that work to lower the level of testosterone, such as Zoladex.

Serious side effects

These lists contain examples of serious side effects that can occur when treating prostate cancer with Zoladex, with Lupron Depot, or with both drugs (when taken individually).

• Can occur with Zoladex:
  • hypercalcemia (high level of calcium in your blood)
  • injection site injury in the spot where Zoladex is inserted, such as hematoma (blood pooling outside of a blood vessel) or hemorrhage (severe bleeding)
• Can occur with Lupron Depot:
  • seizures
• Can occur with both Zoladex and Lupron Depot:
  • allergic reaction
  • depression
  • high blood sugar
  • long QT syndrome (a condition in which your heartbeat is uneven)
  • serious cardiovascular (heart and blood vessel) conditions, including heart attack and stroke
  • spinal cord compression (increased pressure on your spinal cord)
  • tumor flare (growth of a tumor for a very short time)

Effectiveness

These drugs haven’t been directly compared in clinical studies, but studies have found both Zoladex and Lupron Depot to be effective for the palliative treatment of advanced prostate cancer.

A retrospective study was done to compare Zoladex with Lupron Depot in males* with advanced prostate cancer. “Retrospective” means researchers looked at health information that was already available. Specifically, the researchers compared males who received Zoladex with males who received Lupron Depot.

The goal was to see if either medication was better at lowering a hormone called testosterone to castration levels. “Castration” in this sense refers to using a medication to lower testosterone levels to where they’re barely detectable. In the study, there was no difference in the results between males who received Zoladex and those who received Lupron Depot.

* Use of the term “male” within this article refers to a person’s sex assigned at birth.

Costs

Zoladex and Lupron Depot are both brand-name drugs. There are currently no generic forms of either drug. Brand-name medications usually cost more than generics.

The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

Zoladex uses

The Food and Drug Administration (FDA) approves prescription drugs such as Zoladex to treat certain conditions. Zoladex may also be used off-label for other conditions. Off-label use is when a drug that’s approved to treat one condition is used to treat a different condition.

Zoladex for the palliative treatment of advanced breast cancer

Zoladex is FDA-approved to treat advanced breast cancer. This is a type of cancer that begins in the breasts and then spreads to other parts of the body. Advanced breast cancer may extend to the lymph nodes, which are mainly located on the sides of the neck and groin, and beneath your armpits. Advanced breast cancer can also extend to other parts and organs of the body, such as the bones, liver, or brain.

Zoladex is used as a palliative treatment to help ease symptoms such as bone pain. The drug also works to improve the quality of life for females* with advanced breast cancer who are premenopausal (haven’t gone through menopause) or perimenopausal (the stage right before menopause). Zoladex isn’t a cure for advanced breast cancer.

* Use of the term “female” within this article refers to a person’s sex assigned at birth.

Effectiveness for breast cancer

In a clinical study of people with advanced breast cancer, Zoladex was compared with an oophorectomy (surgery to remove one or both ovaries). Researchers found that 22% of people who took Zoladex had their tumor respond, meaning that the tumor shrank or stopped growing, compared with only 12% of people who had an oophorectomy.

Zoladex for endometriosis

Zoladex is FDA-approved to treat endometriosis, a condition in which the tissue that lines the inside of your uterus (womb) grows outside the uterus. The parts of the body that endometriosis most commonly involves are the:

• fallopian tubes, which connect the ovaries and uterus
• ovaries
• pelvis (area between your belly button and groin)

The tissue in these body parts that’s growing abnormally may get bigger or look different. It may be referred to as an endometrial lesion. Because this tissue acts like normal uterine tissue, it thickens and then breaks down during each menstrual cycle (period). This can cause symptoms such as extreme bleeding and painful periods.

Effectiveness for endometriosis

In a study of people who had endometriosis, Zoladex was compared with another drug used for endometriosis called danazol. The researchers looked at how well each medication worked to reduce endometrial lesions. In this study, 63% of people who received Zoladex had a decrease in endometrial lesion size of 50% or more, compared with 42% of people who received danazol.

Zoladex for prostate cancer

Zoladex is FDA-approved to treat prostate cancer that’s locally confined. This type of cancer starts in the prostate gland, which is located between the penis and bladder. “Locally confined” means that the cancer hasn’t spread past the prostate. Zoladex is used with another drug called flutamide to treat this type of prostate cancer before and during radiation therapy. Radiation therapy is a kind of cancer treatment that kills cancer cells using concentrated beams of radiation.

Effectiveness for prostate cancer

In a clinical study, people took Zoladex, the drug flutamide, and radiation therapy, or radiation therapy only. Of the people who received Zoladex, flutamide, and radiation, 16% had local failure within 4 years. “Local failure” means that the prostate cancer was just in the prostate and went away with treatment, but then grew back. In comparison, 33% of the people who received only radiation therapy had local failure within 4 years.

Zoladex for the palliative treatment of advanced prostate cancer

Zoladex is also FDA-approved to treat advanced prostate cancer. “Advanced” means the cancer has spread from the prostate gland to other parts of the body. Zoladex is used as a palliative treatment to help ease symptoms such as bone pain and trouble urinating. The medication also works to improve the quality of life for people with advanced prostate cancer. Zoladex isn’t a cure for the disease.

Effectiveness for advanced prostate cancer

In clinical trials, Zoladex was compared with orchiectomy (surgical removal of the testicles). There was no significant difference in how long people who received Zoladex survived compared with people who had an orchiectomy. There was also no significant difference in the lowering of a hormone called testosterone to castration levels. “Castration” in this sense refers to using a medication to lower testosterone levels to where they’re barely detectable.

Some males* aren’t comfortable having an orchiectomy. These studies helped show that Zoladex is an option for males with advanced prostate cancer who prefer not to have an orchiectomy.

* Use of the term “male” within this article refers to a person’s sex assigned at birth.

Zoladex for uterine bleeding

Zoladex is approved by the FDA to treat abnormal uterine bleeding. With this condition, you menstruate (bleed) at times other than during your normal menstrual cycle. The bleeding isn’t related to another condition or disease. The bleeding also can’t be predicted. It may be very light or heavy, occur for a long time, and occur often.

Zoladex is used to thin the lining of your uterus before an endometrial ablation. This is a procedure in which the lining of your uterus is removed.

Effectiveness for uterine bleeding

A clinical study randomly assigned females* to receive either Zoladex or an injection of a placebo (treatment with no active drug). This was followed by an endometrial ablation. The researchers wanted to see how many females who received Zoladex plus an endometrial ablation didn’t have their period 6 months after treatment.

Six months after surgery, 40% of females who received Zoladex plus an endometrial ablation reported not having their period. This was compared with only 26% of females who received a placebo injection.

* Use of the term “female” within this article refers to a person’s sex assigned at birth.

Off-label uses for Zoladex

In addition to the uses listed above, Zoladex may be used off-label for other uses. Off-label drug use is when a drug that’s approved for one use is used for a different one that’s not approved.

Zoladex for fibroids

Although Zoladex isn’t FDA-approved to treat uterine fibroids, the drug may be prescribed off-label for this use. Uterine fibroids are noncancerous growths in the walls of the uterus. Some females* who have uterine fibroids have symptoms such as heavy menstrual bleeding and pain in their uterus.

Zoladex isn’t a cure for uterine fibroids, but it may help ease symptoms. Usually, Zoladex is used to help shrink fibroids before they’re surgically removed.

The American Academy of Family Physicians recommends Zoladex as an option to decrease fibroid size before a surgery to remove them.

* Use of the term “female” within this article refers to a person’s sex assigned at birth.

Zoladex for PMDD

Zoladex isn’t FDA-approved to treat premenstrual dysphoric disorder (PMDD), but the drug may be prescribed off-label for females* with PMDD.

PMDD can be thought of as a more serious form of premenstrual syndrome (PMS). Females with PMDD have more severe symptoms of PMS, including feeling irritable and tense, and having severe depression. It’s not known what causes PMDD, but it may involve hormone changes during menstruation. Zoladex blocks the hormones that cause menstruation, which may help relieve symptoms of PMDD.

The International Society for Premenstrual Disorders states that Zoladex and other drugs in the same drug class may be options for short-term treatment of PMDD for some females.

* Use of the term “female” within this article refers to a person’s sex assigned at birth.

Common questions about Zoladex

Here are answers to some frequently asked questions about Zoladex.

Does Zoladex cause long-term side effects?

Yes, it’s possible Zoladex may cause long-term side effects. But these weren’t common in clinical studies of the drug.

The studies showed that over time, Zoladex can decrease bone mineral density (BMD). (BMD describes how dense your bone tissue is.) People with a low BMD have an increased risk of osteoporosis. And having osteoporosis can increase your risk for bone fractures. This can occur even after you stop receiving Zoladex.

If you have reduced BMD, your doctor will likely start you on treatment to help prevent osteoporosis.

Another possible long-term side effect of Zoladex is cardiovascular problems. Examples include heart attack and stroke. This side effect was rare with Zoladex, but its risk was increased in males.*

Be sure to let your doctor know if you have any symptoms of cardiovascular problems. These may include chest pain or shortness of breath. It’s also possible to have sudden numbness or weakness of your arm, face, or leg. If needed, your doctor will closely monitor you for cardiovascular problems.

If you have questions about other long-term side effects from Zoladex, talk with your doctor.

* Sex and gender exist on spectrums. Use of the term “male” in this article refers to sex assigned at birth.

Is Zoladex chemotherapy?

No, Zoladex isn’t a chemotherapy drug. Zoladex is a type of hormone therapy that works by reducing the levels of sex hormones such as estrogen and testosterone in your blood.

This is different from the way chemotherapy drugs such as docetaxel (Taxotere) and doxorubicin (Doxil) work. Chemotherapy drugs destroy cells in the body that grow rapidly, including cancer cells. But chemotherapy drugs also destroy other rapidly growing cells. These include blood cells, cells lining the intestines and mouth, and hair follicles (sacs under your skin that hold the roots of your hair). This is why chemotherapy drugs can cause many different side effects throughout the body.

Your doctor may recommend chemotherapy by itself or with hormone therapy to treat advanced breast cancer and prostate cancer. Zoladex may be used with chemotherapy for breast cancer. However, Zoladex isn’t one of the hormone therapies recommended for use with chemotherapy for prostate cancer.

If you have questions about Zoladex, chemotherapy, or other cancer treatments, ask your doctor.

How long does Zoladex stay in your system?

Zoladex may stay in your system for up to 12 weeks.The Zoladex implant is designed to dissolve over time.

For instance, at 28 days, a 3.6-milligram (mg) Zoladex implant is nearly gone and all the medication has nearly been used up. However, in clinical studies, it took up to 12 weeks after the last implant was inserted for hormone levels to return to normal.

What side effects will I have if I stop Zoladex treatment?

This will depend on what you’re using Zoladex to treat. In people with cancer, the tumors may grow after they stop using Zoladex. This could cause a return of previous symptoms, such as bone pain or trouble urinating.

Females* who take Zoladex should find that their regular menstrual periods return within 12 weeks after stopping treatment.

If you’re concerned about possible side effects after you stop using Zoladex, talk with your doctor.

* Use of the term “female” within this article refers to a person’s sex assigned at birth.

Are Zoladex injections painful?

For some people, a Zoladex injection can be painful. In clinical studies, about 3% of people who received Zoladex reported an injection site reaction, such as pain. (The site is the area where Zoladex is placed.)

One study showed that icing the injection area before receiving the implant reduced pain for more than 68% of people.

If you’re concerned about pain while receiving your Zoladex injection, talk with your doctor. They may be able to suggest how you can be more comfortable.

Can I take hormone replacement therapy with Zoladex?

It depends on what condition you’re using Zoladex for. Clinical studies have shown that using hormone replacement therapy with Zoladex may help ease certain symptoms of Zoladex, such as hot flushes. However, hormone replacement therapy shouldn’t affect how Zoladex works.

If you have questions about using hormone replacement therapy while using Zoladex, speak with your doctor.

How Zoladex is administered

Zoladex comes as an implant that’s inserted subcutaneously (under the skin). You’ll go to your doctor’s office or a clinic where a healthcare professional will perform the procedure.

They may numb the injection site prior to giving you the injection. The healthcare professional will pinch the skin of your belly, insert a needle, and inject the Zoladex implant.

Your doctor will give you full instructions on caring for the implant after the procedure.

Zoladex injection site

Zoladex is usually inserted under the skin around your belly button.

Zoladex dosage

Here’s some information about the dosage for the Zoladex implant.

Drug forms and strengths

Zoladex comes as an implant that’s inserted subcutaneously (under the skin), usually around your belly button. You’ll go to your doctor’s office or a clinic where a healthcare professional will perform the procedure.

The Zoladex implant is available in two strengths: 3.6 mg or 10.8 mg.

One 3.6-milligram (mg) Zoladex implant will last for 28 days. One 10.8-mg Zoladex implant will last for 12 weeks. After that, your doctor may want you to have another implant inserted to continue treatment.

Dosage for the palliative treatment of breast cancer

The usual recommended dosage of Zoladex for the palliative treatment of breast cancer is a 3.6-mg implant inserted every 28 days.

Dosage for endometriosis

The usual recommended dosage of Zoladex for endometriosis is a 3.6-mg implant inserted every 28 days, for up to a total of 6 months of treatment.

Dosage for prostate cancer

The usual recommended dose of Zoladex for prostate cancer is a 3.6-mg implant. After 28 days, this should be followed by a 10.8-mg Zoladex implant. You’ll begin this treatment 8 weeks before you have radiation therapy.

Dosage for the palliative treatment of advanced prostate cancer

The usual recommended dosage of Zoladex for palliative treatment of advanced prostate cancer is a 3.6-mg implant inserted every 28 days. Another option is a 10.8-mg implant inserted every 12 weeks.

Dosage for uterine bleeding

The usual recommended dose of Zoladex for uterine bleeding is one or two 3.6-mg implants.

If you have one implant, you’ll typically have the endometrial ablation 4 weeks later. (This is a procedure in which the lining of your uterus is removed.)

If you have two implants, you’ll receive the second implant 4 weeks after the first. Then you’ll typically have the endometrial ablation 2 to 4 weeks later.

What if I miss a dose?

The Zoladex implant releases the drug in your body over a set length of time, so there’s no need for you to remember to take individual doses. The implant will dissolve over time, so you don’t need an appointment to get it removed. Your doctor may want you to have another implant inserted to continue treatment.

The Zoladex implant is designed to release the drug for a few days beyond when your next dose is due. It’s not recommended that you delay your appointment for your next Zoladex implant. But if you need to, know that you’ll still receive the drug for a short time. It’s important that you make every effort possible to stick to either a 4-week or 12-week schedule, depending on your prescribed dosage.

Will I need to use this drug long term?

Zoladex is meant to be used as a long-term treatment. If you and your doctor determine that Zoladex is safe and effective for you, you’ll likely take it long term.

How Zoladex works

Zoladex is used to treat several different conditions. Here’s some information about those conditions and the drug’s mechanism of action (how it works) to treat them.

Prostate cancer

Prostate cancer starts in the prostate gland, which is located between the penis and bladder. Males* with prostate cancer have prostate cells that grow at a rate faster than normal, and the cells try to spread beyond the prostate. The growth of both normal and cancerous prostate cells is triggered by a hormone called testosterone.

Zoladex is used to treat types of prostate cancer that are locally confined or advanced. “Locally confined” means that the cancer hasn’t spread past the prostate. And “advanced” means that the cancer has spread from the prostate gland to other parts of the body.

* Use of the term “male” within this article refers to a person’s sex assigned at birth.

Endometriosis

With endometriosis, tissue grows abnormally outside the uterus (womb). Although this tissue is outside the uterus, it still thickens and bleeds, just like normal uterine tissue does during the menstrual cycle (period). The growth of this tissue is affected by a hormone known as estrogen.

Abnormal uterine bleeding

With this condition, you menstruate (bleed) at times other than during your normal menstrual cycle. The bleeding isn’t related to another condition or disease. The bleeding also can’t be predicted. It may be very light or heavy, it may occur for a long time, and it may occur often. The hormone estrogen plays a role in causing symptoms of abnormal uterine bleeding.

Zoladex is used to thin the lining of your uterus before an endometrial ablation. This is a procedure in which the lining of your uterus is removed.

Advanced breast cancer

Advanced breast cancer is a type of cancer that begins in the breasts and then spreads to other parts of the body. Advanced breast cancer may extend to the lymph nodes, which are mainly located on the sides of the neck and groin, and beneath your armpits. Advanced breast cancer can also extend to other parts and organs of the body, such as the bones, liver, or brain.

What Zoladex does

Zoladex contains the active drug goserelin, which belongs to a class of medications called gonadotropin releasing hormone (GnRH) analogs. (A class of medications is a group of drugs that work in a similar way.) GnRH is a hormone that’s made naturally in your brain. GnRH tells your body to release other hormones, such as follicle stimulating hormone (FSH) and luteinizing hormone (LH). These hormones tell the body to make more sex hormones, such as estrogen and testosterone.

When GnRH levels in your blood become too high, your body automatically stops making LH and FSH. This lowers the levels of sex hormones in your blood.

Sex hormones such as estrogen and testosterone can cause certain cancers, including breast cancer and prostate cancer, to grow. Estrogen can also cause many of the symptoms that occur with endometriosis. By blocking sex hormones, Zoladex can help relieve the symptoms that these conditions cause.

How long does it take to work?

The Zoladex implant will start working right away and will be fully effective within a few weeks.

Within 2 to 4 weeks, the testosterone levels of males* should drop below castration levels. “Castration” in this sense means using a medication to lower testosterone levels to the point where they’re barely detectable.

The estrogen levels of females* should drop below the levels of females who have gone through menopause.

By decreasing the levels of testosterone, estrogen, or both, Zoladex helps prevent the growth of certain cancers. The drop in these hormone levels also helps ease symptoms of conditions such as endometriosis and abnormal uterine bleeding, which are affected by these hormones.

* Use of the terms “male” and “female” within this article refers to a person’s sex assigned at birth.

Zoladex cost

As with all medications, the cost of Zoladex can vary. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Your insurance plan may require you to get prior authorization before approving coverage for Zoladex. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the request and let you and your doctor know if your plan will cover Zoladex.

If you’re not sure if you’ll need to get prior authorization for Zoladex, contact your insurance company.

Financial assistance

If you need financial support to pay for Zoladex, help is available. TerSera Therapeutics LLC, the manufacturer of Zoladex, offers the following:

• Zoladex Co-pay Card (844-864-3014)
• Zoladex Patient Assistance Program (855-686-8725)

For more information and to find out if you’re eligible for support, call the numbers above or visit the program website.

Zoladex vs. tamoxifen

Like Lupron Depot (above), the drug tamoxifen (Soltamox) has uses similar to those of Zoladex. Here’s a comparison of how Zoladex and tamoxifen are alike and different.

Ingredients

Zoladex contains the active drug goserelin. Tamoxifen itself is the active ingredient in tamoxifen.

Zoladex works by blocking the production of certain hormones, including estrogen and testosterone. Tamoxifen works in a different manner. Tamoxifen blocks the effects of estrogen, including growth in breast tissue.

Uses

The Food and Drug Administration (FDA) has approved Zoladex for the treatment of the following:

• Prostate cancer that’s locally confined. Prostate cancer starts in the prostate gland, which is located between the penis and bladder. “Locally confined” means that the cancer hasn’t spread past the prostate. Zoladex is used with another drug called flutamide to treat this type of prostate cancer before and during radiation therapy.
• Advanced prostate cancer. “Advanced” means that the cancer has spread from the prostate gland to other parts of the body. Zoladex is used as a palliative treatment to help ease symptoms such as bone pain and trouble urinating. The medication also works to improve the quality of life for people with advanced prostate cancer. Zoladex isn’t a cure for the disease.
• Endometriosis. With this condition, tissue grows abnormally outside the uterus (womb).
• Abnormal uterine bleeding. With this condition, you menstruate (bleed) at times other than during your normal menstrual cycle (period). Zoladex is used to thin the lining of your uterus before an endometrial ablation. This is a procedure in which the lining of your uterus is removed.
• Advanced breast cancer. This kind of cancer begins in the breast and then spreads to other parts of the body. Zoladex is used as a palliative treatment to help ease symptoms such as bone pain. The drug also works to improve the quality of life for females* with advanced breast cancer who are premenopausal (haven’t gone through menopause) or perimenopausal (the stage right before menopause). Zoladex isn’t a cure for advanced breast cancer.

Tamoxifen has been approved by the FDA:

• to treat metastatic breast cancer* in both males* and females. “Metastatic” is another way of saying that the cancer has spread beyond the breasts to areas such as the liver or lungs.
• to prevent breast cancer in people at high risk for the disease
• as an adjuvant (secondary) treatment for a type of breast cancer that’s called node-positive
• to treat a type of breast cancer that’s called axillary-node negative, after a mastectomy (removal of one or both breasts)

* Use of the terms “male” and “female” within this article refers to a person’s sex assigned at birth.

Drug forms and administration

Zoladex comes as an implant that’s inserted subcutaneously (under the skin), usually around your belly button. You’ll go to your doctor’s office or a clinic where a healthcare professional will perform the procedure.

One 3.6-milligram (mg) Zoladex implant will last for 28 days. One 10.8-mg Zoladex implant will last for 12 weeks. After that, your doctor may want you to have another implant inserted to continue treatment.

Tamoxifen comes as a tablet or liquid that you swallow. You’ll take the drug every day.

Side effects and risks

Zoladex and tamoxifen are both used to treat breast cancer but contain different drugs. Therefore, these medications can cause some similar and some different side effects. Below are examples of these side effects.

Mild side effects

These lists contain examples of mild side effects that can occur with Zoladex, with tamoxifen, or with both drugs (when taken individually) when treating breast cancer.

• Can occur with Zoladex:
  • acne
  • back pain
  • change in breast size
  • decreased libido (lower sex drive)
  • dizziness
  • hair loss
  • headache
  • hirsutism (unusual hair growth on the face or body)
  • insomnia (trouble falling or staying asleep)
  • leg cramps
  • pelvic pain (pain between your belly button and groin)
  • stomach pain
  • sweating
  • infections, such as the common cold
  • fatigue (lack of energy)
  • weight gain
  • vaginitis (irritation and swelling of the vagina)
  • voice changes such as a deeper voice
• Can occur with tamoxifen:
  • changes in menstruation, such as amenorrhea (not having your period) or having irregular periods
  • skin changes, such as redness or rash
  • vaginal discharge
  • weight loss
  • weakness
• Can occur with both Zoladex and tamoxifen:
  • bloating and fluid retention (buildup)
  • hot flashes (also known as hot flushes)
  • mood changes
  • nausea

Serious side effects

These lists contain examples of serious side effects that can occur with Zoladex, with tamoxifen, or with both drugs (when taken individually).

• Can occur with Zoladex:
  • depression
  • high blood sugar
  • long QT syndrome (a condition in which your heartbeat is uneven)
  • serious cardiovascular (heart and blood vessel) conditions, including heart attack and stroke
  • severe injection site injuries, such as hematoma (blood pooling outside of a blood vessel) and hemorrhage (severe bleeding)
  • spinal cord compression (increased pressure on your spinal cord)
  • tumor flare (growth of a tumor for a very short time)
• Can occur with tamoxifen:
  • unusual vaginal bleeding
  • blood clots, including pulmonary embolism (blood clot in the lungs) and stroke*
  • changes in the endometrium (lining of the uterus), including polyps (growths of tissue that aren’t cancer)
  • eye problems, including cataracts
  • serious liver disease, including fatty liver and hepatitis
  • uterine cancer (cancer of the uterus)*
• Can occur with both Zoladex and tamoxifen:
  • allergic reaction
  • hypercalcemia (high level of calcium in your blood)

* Tamoxifen has a boxed warning for stroke, pulmonary embolism, and uterine cancer in females who have a type of cancer called ductal carcinoma in situ (DCIS) or a high risk for breast cancer. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

Effectiveness

These drugs haven’t been directly compared in clinical studies, but studies have found both Zoladex and tamoxifen to be effective for treating advanced or metastatic breast cancer.

Costs

Zoladex is a brand-name drug. It currently doesn’t have any generic forms. Brand-name medications usually cost more than generics. Tamoxifen is a generic medication. It’s available as the brand-name drug Soltamox.

The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

Zoladex use with other drugs

Some drugs in this section may be used off-label. Off-label drug use is when a drug that’s approved for one use is used for a different one that’s not approved.

When treating advanced prostate cancer, Zoladex may be used with a class of medications called anti-androgens. (A class of medications is a group of drugs that work in a similar way.) Anti-androgens are rarely used by themselves but are often given alongside drugs such as Zoladex.

A commonly used anti-androgen is bicalutamide (Casodex). Bicalutamide and other anti-androgens are often given along with Zoladex during the first few weeks of therapy to stop tumor flare. (Tumor flare is the growth of a tumor for a very short time. To learn more, see the “Zoladex side effects” section above.) This is because bicalutamide and other anti-androgens block the first rise in testosterone blood levels that sometimes occur with Zoladex.

Zoladex is often used with tamoxifen in females* with breast cancer that’s early stage and hormone receptor-positive. “Early stage” means that the tumor hasn’t spread beyond the breast. And “hormone receptor-positive” is a type of breast cancer in which certain receptors (special structures that receive and send “signals” in the body) are found in the tumor. The drug’s goal is to lower the risk of the breast cancer coming back. And the females are premenopausal, which means that they haven’t reached menopause.

Zoladex may also be used together with exemestane (Aromasin) in females who are premenopausal or perimenopausal (are in the stage right before menopause). The females have breast cancer that’s locally advanced or metastatic. “Locally advanced” means that the cancer has spread to the chest wall, the skin of the breast, or the lymph nodes around the underarm. And “metastatic” means the cancer has spread beyond the breasts to other parts of the body.

* Use of the term “female” within this article refers to a person’s sex assigned at birth.

Zoladex and alcohol

There’s no known interaction between Zoladex and alcohol. However, consuming too much alcohol while you have a Zoladex implant may increase your risk for losing bone mineral density. This can lead to problems such as osteoporosis, a condition in which your bones develop holes and become more fragile.

If you have a Zoladex implant, talk with your doctor about whether it’s safe for you to consume alcohol.

Zoladex interactions

It’s not known if there are any drug interactions between Zoladex and other medications. If you have questions about taking other drugs while using Zoladex, talk with your doctor.

Zoladex and herbs and supplements

There aren’t any herbs or supplements that have been specifically reported to interact with Zoladex. However, you should still check with your doctor or pharmacist before using any of these products while taking Zoladex.

Zoladex and foods

To date, there aren’t any foods that have been reported to interact with Zoladex. If you have questions about eating certain foods while taking Zoladex, speak with your doctor.

Zoladex and pregnancy

If you’re pregnant, you shouldn’t use Zoladex unless you’re taking it as a palliative treatment for advanced breast cancer. The drug may cause miscarriage or harm the baby if given to a pregnant woman. If you’re able to become pregnant, your doctor will order a pregnancy test before you start using Zoladex to make sure that you aren’t pregnant.

There are no studies of pregnant people who have used Zoladex. Animal studies showed that using Zoladex during pregnancy had harmful and sometimes even fatal effects on offspring. However, animal studies don’t always predict how a drug will affect humans.

If you’re pregnant or planning to become pregnant, talk with your doctor about your treatment options.

Zoladex and birth control

It’s recommended that Zoladex not be used during pregnancy. If you’re sexually active and can become pregnant, you’ll need nonhormonal birth control while using Zoladex and for 12 weeks after you stop treatment.

For more information about your birth control needs while you’re using Zoladex, talk with your doctor.

Zoladex and breastfeeding

We don’t know if Zoladex is safe to use while you’re breastfeeding because it isn’t known if Zoladex passes into human breast milk. Animal studies have shown that goserelin, the active ingredient in Zoladex, is present in breast milk. However, animal studies don’t always predict how the drug will act in humans.

If you’re thinking about breastfeeding while using Zoladex, first talk with your doctor. They may recommend a treatment other than Zoladex or recommend that you stop breastfeeding.

Zoladex precautions

This drug comes with several precautions. Before taking Zoladex, talk with your doctor about your health history. Zoladex may not be right for you if you have certain medical conditions or other factors affecting your health. These include:

• Allergic reactions. If you’re allergic to Zoladex or any of its ingredients, you shouldn’t use Zoladex. And if you’ve had an allergic reaction to other medications in the same drug class as Zoladex, you also should avoid using Zoladex. (A drug class is a group of medications that work in a similar way.) Zoladex is in the gonadotropin releasing hormone (GnRH) analog drug class. If you’re unsure whether you’ve had an allergic reaction to Zoladex or a similar drug, talk with your doctor.
• Diabetes. Zoladex can make it harder for people with diabetes to control their blood sugar. Before you receive a Zoladex implant, talk with your doctor about your diabetes. They may need to adjust your treatment before or after you receive an implant.
• Heart conditions. Zoladex can cause serious and even fatal cardiovascular (heart and blood vessel) problems, including heart attack or stroke. If you already have heart disease, Zoladex may increase this risk further. Before you receive a Zoladex implant, talk with your doctor about your heart health. This includes any history of arrhythmia (abnormal heart rhythms) or a heart condition called long QT syndrome. Your doctor may suggest a treatment other than Zoladex.
• Pregnancy. If you’re pregnant, you shouldn’t use Zoladex unless you’re taking it as a palliative treatment for advanced breast cancer. For more information, please see the “Zoladex and pregnancy” and “Zoladex and birth control” sections above.
• Breastfeeding. It’s not known if Zoladex is safe to use while you’re breastfeeding. For more information, please see the “Zoladex and breastfeeding” section above.

Note: For more information about the potential negative effects of Zoladex, see the “Zoladex side effects” section above.