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Enzalutamide (Xtandi)

Enzalutamide is a type of hormone therapy treatment for advanced prostate cancer. This page tells you about


What enzalutamide is

Enzalutamide (pronounced en-zal-loo-tah-my-de) is also known by its brand name Xtandi (pronounced ex-tan-dee) and as MDV3100. It is a hormone therapy treatment for men with advanced prostate cancer.


How enzalutamide works

Prostate cancers depend on male hormones in order to grow. The hormones are called androgens and include testosterone.

Enzalutamide is a type of drug called an androgen receptor antagonist. It blocks the male hormones from signalling to the cancer cell to grow. So it can stop the growth of the cancer or shrink it for some time.


How you have enzalutamide

You take enzalutamide as capsules, once a day. You swallow them whole with a glass of water.

It is very important that you take the capsules according to the instructions your doctor or pharmacist gives you. You should take the right dose, not more or less. And never stop taking a cancer drug without talking to your specialist first.

If you accidentally take more capsules than prescribed, contact your doctor straight away. You may have an increased risk of seizures (fits) or other side effects.

If you forget to take the capsules at the usual time, take them as soon as you remember. If you forget to take them for the whole day, take your usual dose the following day. Don’t take a double dose to make up for the missed dose. If you forget to take the capsules for more than one day, talk to your doctor straight away.

We've listed the side effects associated with enzalutamide below. You can use the links to find out more about each effect. Where there is no link, please use the search box at the top of the page. Or you can look at the cancer drug side effects section.


Common side effects

More than 10 in every 100 people have one or more of these.

  • Tiredness and weakness (fatigue) occurs in about 1 in 3 men (33%)
  • Hot flushes happen in about 2 in 10 men (20%)
  • Headaches affect just over 1 in 10 men (10%)
  • Loss of fertility – you may not be able to father a child after this treatment. Talk to your doctor before starting treatment if you think you may want to have a baby in the future. You may be able to store sperm beforehand

Occasional side effects

Between 1 and 10 in every 100 people have one or more of these effects.

  • Pain or aching in joints and muscles
  • An increased risk of infection due to a drop in the number of white blood cells
  • Muscle spasms
  • Muscle weakness
  • Back pain
  • Higher blood pressure
  • Dizziness
  • Swollen feet and ankles due to fluid build up (known as peripheral oedema)
  • Dry and itchy skin
  • Balance problems
  • Weaker bones
  • Memory problems
  • Difficulty thinking clearly
  • Anxiety
  • Hallucinations
  • Diarrhoea – drink plenty of fluids if you have diarrhoea and let your doctor or nurse know if it gets worse or lasts for more than 3 days
  • Difficulty sleeping
  • Blood in the urine – let your doctor or nurse know if you have this

Rare side effects

Fewer than 1 in 100 men have these effects

  • A fit (seizure) – if you have a seizure, stop taking enzalutamide and see your doctor straight away
  • Bruising more easily due to a drop in platelets – you may have nosebleeds, or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae)

Important points to remember

You may have a few of the side effects mentioned on this page. They may be mild or more severe. A side effect may get better or worse through your course of treatment. Or you may get more side effects as the course goes on. This depends on

  • How many times you've had the drug before
  • Your general health
  • The amount of the drug you have (the dose)
  • Other drugs you are having

Coping with side effects

Talk to your doctor, pharmacist or nurse about all your side effects so they can help you manage them. They can give you advice or reassure you. Your nurse will give you a contact number to ring if you have any questions or problems. If in doubt, call them.

Other medicines

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies. Many drugs react with enzalutamide and may change the way that it works or increase the risk of side effects.


This drug may harm a developing baby. You need to use reliable contraception while having the drug and for about 3 months after the end of treatment if your partner is pregnant or could become pregnant. Talk to your doctor or nurse about contraception before starting treatment.

Sorbitol and enzalutamide

This medicine contains sorbitol (a type of sugar). If you have intolerance to some sugars, contact your doctor before taking this medicine.


More information about enzalutamide

This page does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information, look at the Electronic Medicines Compendium website at www.medicines.org.uk.

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at www.mhra.gov.uk.

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Updated: 31 December 2014