What Do You Need to Know Before Taking Antiandrogen Medication for Prostate Cancer?

In the U.S., prostate cancer is the second leading cause of cancer death in men. About 1 in 8 men will develop prostate cancer during their lifetime. Treating prostate cancer can be complicated. There are many different cancer stages and several types of treatment.

Antiandrogen medications can be used as hormone therapy to treat prostate cancer. These oral medications are usually combined with other hormone therapies. Some examples of antiandrogens are bicalutamide (Casodex) and enzalutamide (Xtandi).

Read on to learn what you should know before taking an antiandrogen medication for prostate cancer.

How do antiandrogen medications work?

Androgens are a group of sex hormones. Testosterone is the most well-known androgen. Some forms of prostate cancer use testosterone to grow. Stopping testosterone production and blocking its effects can cut off the supply to the cancer cells.

Antiandrogen medications block testosterone’s effects. This can help prevent the hormone from attaching to the binding site within cancer cells. These medications are also called androgen receptor blockers or androgen receptor antagonists. 

Antiandrogens can help shrink or slow the growth of prostate cancer cells. They may also prolong survival when used for castration-resistant prostate cancer (CRPC).

There are currently six FDA-approved antiandrogen medications available:

1) Apalutamide (Erleada)

2) Bicalutamide (Casodex)

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3) Darolutamide (Nubeqa)

4) Enzalutamide (Xtandi)

5) Flutamide (Eulexin)

6) Nilutamide (Nilandron)

Antiandrogens were some of the first medications studied for treating prostate cancer. But some are more recent discoveries than others. Apalutamide, darolutamide, and enzalutamide are considered “newer antiandrogens.” They more strongly block the androgen receptor than the older antiandrogens such as flutamide, nilutamide, and bicalutamide.

What happens to your body when androgen effects are blocked?

Blocking testosterone’s effects can result in a change or loss in masculine characteristics. Testosterone is responsible for the development of:

• The growth and maturity of the prostate

• The growth of the penis and testicles

• The ability to have erections and ejaculate

• The growth of facial, pubic, and body hair

• Muscle and bone development

• Voice changes 

So you may notice a change in these characteristics due to androgen’s effect on testosterone. This is the main reason for many of the side effects from antiandrogens. We’ll further discuss the side effects of antiandrogens below.

How are antiandrogen medications dosed?

Antiandrogen medications are oral medications. There are three dosage regimens:

1. Once-daily dose: apalutamide, bicalutamide, enzalutamide, and nilutamide

2. Twice-daily dose: darolutamide 

3. Three-times-daily dose: flutamide 

You may swallow one or more pills with each dose, depending on the medication. Make sure to read your prescription label carefully. Check with your cancer specialist if you’re unsure what time(s) you should take your medication.

Darolutamide is the only antiandrogen medication that needs to be taken with food. The others can be taken with or without food. It’s important to take your doses on a regular schedule, as instructed by your cancer specialist.

Do you take antiandrogen medications alongside other treatment options for prostate cancer?

Yes, antiandrogen medications are usually combined with testosterone-lowering treatments for prostate cancer. Antiandrogen medications don’t stop your body from making testosterone, and high levels of testosterone may also make antiandrogens less effective. So other treatments or surgical procedures are usually recommended along with these medications.

Examples of testosterone-lowering treatment options that may be combined with antiandrogen medications include:

• Orchiectomy: This is a surgical procedure that removes the testicles.

• Luteinizing hormone-releasing hormone (LHRH) agonists: These medications stop the testicles from making testosterone. One example is leuprolide (Lupron, Eligard).

• Luteinizing hormone-releasing hormone (LHRH) antagonists: These medications stop the brain from signaling the testicles to make testosterone. One example is relugolix (Orgovyx).

How long do you have to take antiandrogen medications?

The length of treatment varies, and it depends on the type and stage of prostate cancer you have. How long you take an antiandrogen medication may be different than what’s discussed here.

Some people only take these medications for a few weeks when they first start a LHRH agonist. LHRH agonists cause a temporary testosterone boost while the body gets used to them. This is called a testosterone flare, which can cause pain or other side effects. It can also sometimes cause the cancer to progress. Antiandrogen medications can help prevent the effects of that  temporary hormone surge.

Long-term use of antiandrogens can improve survival in men with metastatic hormone sensitive prostate cancer and non-metastatic CRPC. They also have a well-established safety track record over many years. However, prostate cancer can become resistant to hormone therapies over time. This means hormonal treatments stop working. For some people this can happen within a few months. For others, it may take many years before this happens.

The first sign of hormone resistance is a rising prostate-specific antigen (PSA). PSA is a protein the prostate normally makes. PSA levels are usually higher when men have prostate cancer. During treatment, PSA levels aren’t supposed to keep rising. So if this is happening, it could mean the cancer has become resistant to the treatment. 

Occasionally, imaging can show the cancer growing or spreading — even if PSA levels haven’t changed. That’s why regular imaging is recommended along with PSA and testosterone blood tests. These will help your healthcare provider make sure your treatments are still effective.

Discuss how long you may take antiandrogen medication with your cancer specialist. They’ll be able to give you a more accurate answer based on how your cancer is responding to treatment.

What happens if you stop taking antiandrogen medication too soon?

As described above, antiandrogen medications help manage side effects of a testosterone flare. Stopping them early could cause pain, or it could make other symptoms worse.

Some cancers become dependent on antiandrogen medications. When this happens, stopping the antiandrogen can actually lower PSA levels for several months. 

Cancer keeps improving in 10% to 30% of people with CRPC who stop taking antiandrogen medications. This is called the antiandrogen withdrawal effect. But usually this is only temporary and does not mean the cancer is cured. You’d need to be followed closely if these medications are stopped, as most people’s cancers will continue to progress.

It’s important to take your medication as prescribed. You should always check with your cancer specialist before stopping an antiandrogen medication.

What are the known side effects of antiandrogen medications?

Many side effects from antiandrogen medications are related to the blocking of testosterone. Side effects are similar to those from an orchiectomy or other hormone therapies.

Common side effects of antiandrogen medications include:

• Rash, particularly with apalutamide (28% risk)

• Diarrhea, particularly with flutamide

• Feeling tired

• Hot flashes

• Dizziness

• Nausea

• Sexual side effects, including erectile dysfunction

• Loss of bone density and higher risks of broken bones

• Loss of muscle and lower stamina

• Breast growth and tenderness (gynecomastia)

• Trouble concentrating and possible memory problems

• Higher cholesterol levels

• Weight gain

For some, dizziness could raise the risk of falls or accidental injuries. Be careful when changing positions. Tell your healthcare provider if you’re feeling too dizzy while taking these medications.

Stomach-related side effects (e.g., diarrhea) are more likely if you’re also using an LHRH agonist. Let your cancer specialist know if these side effects become too bothersome.

Newer antiandrogen medications have been linked to heart problems for some people. Make sure your cancer specialist knows if you have any heart conditions. This could make a difference in which medication your provider recommends. Enzalutamide and apalutamide can cause high blood pressure. Regular home blood pressure monitoring during these treatments is recommended. Your provider may also recommend using other methods to help lower blood pressure, such as medications, diet, or exercise.

Liver damage is also possible with antiandrogen medications. But the risk of this side effect is higher with some antiandrogens — such as bicalutamide — than others. You’ll likely have regular blood tests done to watch for this side effect.

In rare cases antiandrogen medications can cause seizures, particularly with enzalutamide and apalutamide. But this risk is usually low for people with no history of seizures. Let your healthcare provider know if you have a history of seizures, a brain tumor or recent stroke, or take medications that may raise the risk of seizures.

How to save on antiandrogen medications

There are ways to save on your antiandrogen medication. GoodRx can help you navigate your options, which may include GoodRx discounts, copay savings cards, and patient assistance programs. You can find antiandrogen prices as low as $15 with a free GoodRx discount.

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Written by:

Austin Ulrich, PharmD, BCACP

​​Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. Ulrich’s experience includes direct patient care in hospital and community pharmacies.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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