Diethylstilbestrol (Stilboestrol®)

Diethylstilbestrol is a hormonal therapy drug used to treat prostate cancer. It’s best to read this information with our general information about prostate cancer.

You have diethylstilbestrol as tablets. Your cancer doctor or nurse will tell you how long you take it for.

Like all hormonal therapy drugs, diethylstilbesterol can cause side effects. Some of these can be serious so it’s important to read the detailed information below. How hormonal therapy affects people varies from person to person. Your doctor or nurse can talk to you more about this and give you advice on how to manage side effects.

Tell your doctor or nurse straight away if you feel unwell or have severe side effects, including any we don’t mention here. If you need to see a health professional for any reason other than cancer, always tell them that you are having this treatment.

How diethylstilbestrol works

Hormones are substances produced naturally in the body. They act as chemical messengers and help control the activity of cells and organs. Hormonal therapies interfere with the way hormones are made or how they work in the body.

Most prostate cancers need the hormone testosterone to grow. Almost all testosterone in men is made by the testicles. A very small amount is made by the adrenal glands, which sit above the kidneys.

Diethylstilbestrol reduces the amount of testosterone made by your body. This reduces testosterone levels and may shrink the prostate cancer or stop it growing.

When diethylstilbestrol is given

Diethylstilbestrol is used to treat prostate cancer. It is usually used when other hormonal treatments are no longer helping to control prostate cancer.

Taking your tablets

You take diethylstilbestrol as tablets once a day. Take them at the same time each day.

Always take your tablets exactly as your nurse or pharmacist explained. This is important to make sure they work as well as possible for you.

Do not stop taking any of your tablets unless your doctor tells you to. Here are some important things to remember:

  • If you forget to take your tablets, just take your usual dose the next day.  Don’t take a double dose.
  • Keep tablets in the original package and at room temperature, away from heat and direct sunlight.
  • Keep them safe and out of the sight and reach of children.
  • Get a new prescription before you run out of tablets and make sure you have plenty for holidays.
  • Return any remaining tablets to the pharmacist if your treatment is stopped.

You can usually keep taking diethylstilbestrol for as long as it is controlling the cancer.

Possible side effects of diethylstilbestrol

We explain the most common side effects of diethylstilbestrol here. We also include some rarer side effects. You may get some of the side effects we mention, but you are very unlikely to get all of them. If you are having other drugs as well, you may have some side effects that we don’t list here.

You will see a doctor or nurse regularly while you have this treatment. Always tell your cancer doctor or nurse about the side effects you have. They can prescribe drugs to help control them and give you advice about managing them. Don’t stop taking diethylstilbesterol without talking to your doctor first.

More information about this drug

We’re not able to list every side effect for this treatment here, particularly the rarer ones. For more detailed information you can visit the Medicines and Healthcare products Regulatory Agency.

Breast swelling or tenderness

You may develop breast swelling or tenderness. This is called gynaecomastia. Your doctor can advise you about how this can be treated or prevented.

Sexual effects

Most men lose their sex drive and have erection difficulties during hormonal therapy. These often return to normal after you stop taking the drug, but some men continue to have difficulties after treatment is over. Your doctor can prescribe treatments to help with erection difficulties but these don’t affect sex drive.

If you need support coping with sexual difficulties, your nurse or doctor can give you information and refer you for specialist support services.

Build-up of fluid

You may put on weight or your ankles and legs may swell because of fluid building up. Tell your doctor or nurse if this happens. If your ankles and legs swell it can help to put your legs up on a footstool with a pillow.

Feeling sick

This is usually mild. Your doctor can prescribe anti-sickness drugs if needed.


You may feel tired and lack energy while taking diethylstilbestrol. Try to pace yourself if you feel tired. Aim for a balance between resting and being physically active. Regular exercise can reduce tiredness in men on hormonal therapy. Ask your doctor or nurse what is safe for you to do.


This treatment can cause headaches in some men. If you had migraines (a severe type of headache) before starting diethylstilbestrol, these may get worse. Let your doctor know if are having more headaches than usual.

Skin changes

Diethylstilbestrol can make some areas of skin darken. Protecting your face and neck from the sun may help reduce this. Use a high factor sun cream (SPF 30 or above) on your face and neck before going out in the sun.

Some men develop a skin rash but this is usually mild and often gets better without treatment. Tell your doctor if you notice any skin changes.

Weight gain and loss of muscle strength

You may gain weight, particularly around your waist, and you may lose some muscle strength. Eating a healthy diet and keeping physically active can help control your weight. Resistance exercises, such as lifting weights, may help you to reduce loss of muscle strength. Ask your doctor or nurse for advice.

Mood changes

You may experience mood swings. Some men can feel low or depressed. Tell your doctor if if you notice mood changes.

High blood pressure

Diethylstilbestrol may cause an increase in blood pressure. You may have regular blood pressure checks when taking this drug.

Blood clots (thrombosis)

Diethylstilbestrol can increase the risk of getting a blood clot. Tell your doctor immediately if you have chest pain or if you have redness, pain, warmth, swelling or tenderness in an arm or leg.

Some doctors may prescribe a low dose of aspirin while you are taking diethylstilbestrol. This helps to prevent blood clots.

Changes in blood sugar levels

Diethylstilbestrol may raise your blood sugar levels. Symptoms of raised blood sugar include feeling thirsty, needing to pass urine more often and feeling tired. Tell your doctor or nurse if you have these symptoms.

If you have diabetes, your blood sugar levels may be higher than usual. Your doctor will talk to you about how to manage this.

Less common side effects of diethylstilbestrol

Effects on gall bladder or liver

Rarely, this drug can cause gallstones and jaundice. Tell your doctor straight away if you notice your skin or the whites of your eyes becoming yellow.

Contact lens wearers

Diethylstilbestrol can cause eye discomfort in contact lens wearers. Tell your doctor if you are affected.

Other information about diethylstilbestrol

Other medicines

Diethylstilbestrol can interact with other drugs. This includes medicines you can buy in a shop or chemist. Tell your doctor about any medicines you are taking, including ones you can buy for yourself. This includes complementary therapies, vitamins and herbal drugs.

Medical treatment

If you need to go into hospital for any reason other than the cancer, always tell the doctors and nurse that you are taking diethylstilbestrol. You should tell them the name of your cancer specialist so that they can ask for advice.