Bicalutamide (Casodex) | Cancer Research UK
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What bicalutamide is

Bicalutamide is a type of hormone therapy known as an anti androgen treatment. It is a treatment for prostate cancer.


How bicalutamide works

Prostate cancer depends on the male sex hormone, testosterone, to grow. Testosterone is a type of hormone called an androgen. Bicalutamide is a an anti androgen. It stops testosterone reaching the cancer cells. This can shrink the cancer or slow its growth.


How you have bicalutamide

You take bicalutamide as a tablet, once a day. You swallow the tablet whole with a drink of water. If you are having bicalutamide to stop a flare reaction, you take it for a few days before starting the LH blocker, and stay on it for about 4 to 6 weeks.

It is very important that you take tablets according to the instructions your doctor or pharmacist gives you. For example, whether you have a full or empty stomach can affect how much of a drug gets into your bloodstream. 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 bicalutamide than you should, talk to your doctor or go to a hospital straight away. 

If you forget to take a dose, skip the missed dose and take the next dose at the usual time. Don't take a double dose. 


Tests during treatment

You have blood tests before starting treatment and regularly during your treatment. The tests check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.


About side effects

We've listed the side effects associated with bicalutamide. You can use the links to find out more about each side effect. Where there is no link, please go to our information about cancer drug side effects or use the search box at the top of the page.

You may have a few side effects. They may be mild or more severe. A side effect may get better or worse through your course of treatment. Or more side effects may develop 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)

The side effects may be different if you are having bicalutamide with other medicines.

Tell your doctor or nurse straight away if any of the side effects get severe.


Temporary side effects when treatment starts

You may have an increase in symptoms called tumour flare for the first few weeks of the treatment. To try to prevent this your doctor may give you another type of hormone drug to start with, such as buserelin (Suprefact), goserelin (Zoladex), leuprorelin (Prostap) or triptorelin. 

The symptoms of tumour flare include

  • Increased pain or difficulty passing urine
  • Bone pain
  • Back pain
  • Blood in the urine  
  • A pins and needles feeling in the legs

Tell your doctor or nurse if you have any of these effects.


Common side effects

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

  • A low sex drive (low libido) affects most men
  • Hot flushes and sweats affect about 5 out of 10 men (50%). Unfortunately some men have them for as long as they stay on treatment. Tell your doctor or nurse if your hot flushes are difficult to cope with
  • Breast tenderness and swelling – this can affect about 4 out of 10 men (40%) and can be distressing. If it is a problem for you, speak to your doctor and they can prescribe treatment to help
  • Problems getting an erection (impotence) – this may improve after you finish treatment
  • Pain – about 3 out of 10 men (30%) have general body pain, more than 1 out of 10 men (15%) have some back pain, and 1 out of 10 men (10%) have some pain in their lower tummy area
  • Feeling sick or being sick affects about 1 in 10 men (10%) – this is usually mild and can be controlled by anti sickness tablets
  • Feeling weak
  • Dizziness - don't drive or operate machinery if you have this
  • A skin rash or dry skin and itching
  • Constipation – drink plenty of fluids. Your doctor or nurse can prescribe laxatives if you are constipated for more than 3 days
  • Blood in your urine – tell your doctor or nurse straight away if you have this

Occasional side effects

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

  • Loss of appetite
  • Feeling sleepy – this usually improves within a few weeks of starting treatment
  • Indigestion
  • Changes in the way your liver works – some men need to stop taking the drug. The liver nearly always goes back to normal after treatment ends 
  • A cough and breathlessness affects about 1 in 20 men (5%)
  • Heart changes – bicalutamide can affect the way the heart works in about 1 in 20 men (5%). This can cause an increase in blood pressure and swelling of the legs (oedema). Let you doctor or nurse know straight away if you have any chest pain
  • Low levels of red blood cells (anaemia) that may cause tiredness and breathlessness
  • 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. Men may be able to store sperm before starting treatment
  • Wind (flatulence) – peppermint may help
  • Sadness or depression – this usually improves within a few weeks of treatment. If it goes on for longer, talk to your doctor or nurse about getting some help
  • Hair thinning or extra hair growth
  • Dry skin or a skin rash and itching
  • Weight gain

Rare side effects

Fewer than 1 in 100 people have these.

  • An allergic reaction – let your nurse or doctor know straight away if you have a sudden skin rash, itching, breathlessness, or swelling of the lips, face or throat
  • Difficulty in sleeping at night
  • Lung changes causing severe breathlessness or breathlessness that suddenly gets worse – tell your doctor or nurse straight away if you have this

Important points to remember

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. Some drugs can react together. 


This drug may harm a baby developing in the womb. It is important not to father a child while you are having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.

Lactose and bicalutamide

Bicalutamide contains a type of sugar called lactose. If you have an intolerance to some sugars, contact your doctor before taking this medicine.


More information about bicalutamide

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

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

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Updated: 16 October 2015