Key takeaways

  • Xtandi, a medication for prostate cancer, can cause side effects. Xtandi side effects range from mild issues like constipation and fatigue to more serious ones, such as seizures or heart problems.
  • Certain preexisting conditions, like heart disease or a history of seizures, may affect whether Xtandi is a suitable treatment option.
  • Keep an open communication with your healthcare professional when taking Xtandi. And let them know right away if you notice any new or worsening side effects.

Xtandi (enzalutamide) is prescribed to treat prostate cancer. Specifically, it’s used when:

  • surgery to remove prostate cancer or hormone treatment to lower testosterone levels hasn’t worked, or
  • prostate cancer has spread to other parts of the body (metastatic prostate cancer) and responds to medication or surgery to lower testosterone levels

Xtandi comes as capsules and tablets that you swallow. If you and your doctor determine that it’s safe and effective for you, you’ll likely take it long term.

Keep reading to learn about the common, mild, and serious side effects Xtandi can cause. To learn more about this drug, including its uses, dosage, and cost, read this Xtandi overview article.

The use of binary terms such as “male” and “female” or “men” and “women” in this article reflects the language of the sources we’ve used. Unless otherwise noted, it’s unclear whether the research we reference included participants with expansive gender identities.

Xtandi can cause certain side effects, some more common than others. These side effects may be temporary, lasting a few days to weeks.

Talk with your doctor if side effects do not go away, get worse, or become too difficult to tolerate.

Xtandi’s most commonly reported side effects in studies include:

For more information about some of these side effects, see “Tips for managing side effects.”

Mild side effects have been reported with Xtandi. These include:

In most cases, these side effects should be temporary, and some may be easily managed. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. Do not stop taking Xtandi unless your doctor recommends it.

Xtandi may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

For more information about some of these side effects, see “Tips for managing side effects.”

Xtandi may cause serious side effects. The following list may not include all possible serious side effects of the drug. For more information, you can refer to Xtandi’s prescribing information.

Serious side effects that have been reported include:

If you develop serious side effects while taking Xtandi, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medication safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect while taking Xtandi and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Allergic reaction

For some people, Xtandi can cause an allergic reaction.

In general, symptoms of an allergic reaction can be mild or serious.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should keep taking Xtandi.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Xtandi, they may have you switch to a different treatment.

There may be things you can do to help make certain Xtandi side effects more manageable. If you have ongoing, worsening, or bothersome side effects, talk with your doctor or pharmacist. They can suggest tips for managing them or recommend other available treatment options for your condition.

Fatigue

Fatigue was one of the most common side effects in Xtandi’s studies. But keep in mind that fatigue can also be a symptom of cancer. And Xtandi is used to treat prostate cancer.

What might help

If you experience symptoms of fatigue, such as low energy or tiredness, talk with your doctor. Depending on the severity of your condition, they’ll discuss options for you to consider.

For mild fatigue, they may suggest lifestyle changes such as:

  • eating a balanced diet
  • avoiding alcohol (if you drink)
  • managing stress
  • getting plenty of rest

If you have severe fatigue that interferes with your quality of life, they may have you stop Xtandi treatment.

Diarrhea

Taking Xtandi can cause diarrhea. This is a common side effect of the drug. If diarrhea is severe, it can cause dehydration from extreme fluid loss.

Xtandi can also cause other digestive side effects, such as constipation and nausea.

What might help

For mild cases of diarrhea, your doctor may suggest:

  • taking an over-the-counter antidiarrheal medication, such as loperamide (Imodium)
  • drinking adequate fluids to avoid dehydration

But if you experience diarrhea that’s bothersome or serious, call your doctor. They’ll discuss the severity of your symptoms and your treatment options. In some cases, if diarrhea is severe, they may have you temporarily stop taking Xtandi until your symptoms improve.

If you have questions about this side effect of Xtandi, talk with your doctor or pharmacist.

Hot flashes

Xtandi can cause hot flashes. This is a common side effect the drug can cause because it lowers testosterone levels in the body. Signs include sudden, intense sensations of heat that aren’t related to hot weather.

Symptoms may include:

What might help

To ease mild symptoms, you can try:

  • avoiding triggers, such as:
    • spicy foods
    • alcohol (if you drink)
    • hot drinks
  • making lifestyle changes, such as:
    • eating a low fat diet
    • getting regular exercise
    • getting good quality sleep

If you have severe symptoms, call your doctor. They may discuss other treatment options with you.

If you have questions about the likelihood of hot flashes with Xtandi treatment, ask your doctor or pharmacist for more information.

Posterior reversible encephalopathy syndrome (PRES)

Xtandi can cause a serious brain condition called posterior reversible encephalopathy syndrome (PRES), which occurs due to swelling in the brain. This side effect was not reported in studies of the drug. But it was reported by people taking Xtandi after the drug was approved for use.

Symptoms can include:

What might help

If you experience symptoms of PRES, such as a seizure or sudden headache with vision changes, call your doctor right away. They’ll order certain diagnostic tests to check for PRES. If you have this condition, they’ll likely have you stop taking Xtandi and discuss other treatments with you.

Here are answers to some commonly asked questions about Xtandi’s side effects.

Does the 40-mg strength of Xtandi cause different side effects than the 80-mg strength?

It’s not likely. Side effects that were reported in studies of the drug were based on a dosage of 160 milligrams (mg) taken once daily. This is the recommended dosage for prostate cancer.

A 2021 study of enzalutamide (the active ingredient in Xtandi) showed that starting treatment at lower doses (between 40 mg and 120 mg) didn’t lower the risk of side effects in people taking this drug to treat castration-resistant prostate cancer. (This is when prostate cancer continues growing even after a person receives therapy to lower their testosterone levels.)

Xtandi is available in both 40-mg and 80-mg strengths. Your doctor may prescribe either a single strength or a combination of strengths to equal your total daily dose. They’ll prescribe the strength and dosage that works best for you based on your individual situation.

If you have questions about Xtandi’s side effects, speak with your doctor or pharmacist.

Will stopping Xtandi cause certain side effects?

It’s unlikely. This was not reported in studies of the drug. Whether you experience certain side effects of Xtandi depends on your individual situation. This includes your overall health, other drugs you take, and other factors. Your doctor will talk with you about possible side effects of Xtandi and what you can expect before you begin treatment.

Do not stop taking Xtandi on your own. If you’re concerned about certain side effects and want to stop taking this drug, talk with your doctor first.

In rare cases, people receiving certain hormone treatments for prostate cancer may experience antiandrogen withdrawal syndrome. This is when prostate-specific antigen (PSA)* levels drop after stopping antiandrogen drugs such as Xtandi. High PSA levels can be one indicator of prostate cancer risk.

A 2015 study found that a few patients experienced lower levels of PSA after stopping enzalutamide. This is a positive reaction that happens rarely. Scientists aren’t sure why it happens and are still learning about this effect.

* PSA is a protein made by the prostate gland.

Can Xtandi cause eye-related side effects?

Eye-related side effects are not common with this drug. But in rare cases, people taking Xtandi can develop a condition called posterior reversible encephalopathy syndrome (PRES). This side effect was not reported in Xtandi’s studies. But there have been reports of this condition after the drug became available for use. PRES is a serious brain disorder that can cause:

  • vision changes
  • blindness
  • serious brain-related side effects, including:
    • headache

If you experience sudden eye-related problems with Xtandi, call your doctor right away. They’ll determine whether you have PRES and will likely have you stop treatment with this drug.

For more information about this side effect, see the prescribing information for Xtandi or talk with your doctor.

If I use Lupron with Xtandi, will I experience different side effects?

It’s possible. Lupron (leuprolide acetate) is a kind of hormone treatment used to lower testosterone levels in people with prostate cancer. Lupron has some similar and some different side effects than Xtandi.

Taking both drugs may increase your risk of certain side effects, such as:

Side effects of Lupron itself that don’t occur with Xtandi include:

If your doctor prescribes Lupron with Xtandi, they’ll discuss the possible side effects of both drugs and what to expect with treatment.

Is nausea a side effect of Xtandi?

It can be. While not a common side effect in Xtandi studies, nausea did occur in some people during treatment. For most people, this side effect was temporary and went away as they continued taking the drug.

If you experience serious nausea that’s bothersome with this drug, talk with your doctor. They’ll discuss ways to manage this side effect and determine whether you should stop Xtandi treatment.

Before taking Xtandi, discuss your health history with your doctor. Xtandi may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Also, Xtandi may cause harm to an unborn fetus. If you are taking Xtandi for prostate cancer, use effective birth control, such as a condom, during sex with partners who can become pregnant. You should do this throughout Xtandi treatment and for 3 months after stopping the drug.

If you have questions about any of these risks, talk with your doctor or pharmacist.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.