Hydroxycarbamide (Hydrea, hydroxyurea) | Cancer Research UK
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Hydroxycarbamide (Hydrea, hydroxyurea)

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This page tells you about the chemotherapy drug hydroxycarbamide (which used to be called hydroxyurea) and cancer treatment. It also discusses the possible side effects. There are sections about


What hydroxycarbamide is

Hydroxycarbamide is used to treat chronic myeloid leukaemia (CML) and cancer of the neck of the womb (cervical cancer). For cervical cancer it is given in combination with radiotherapy.

Hydroxycarbamide may also sometimes be used to treat other types of cancer such as acute myeloid leukaemia, head and neck cancers (before radiotherapy treatment) and ovarian cancer.


How hydroxycarbamide works

Hydroxycarbamide is one of a group of chemotherapy drugs known as anti metabolites. These drugs stop cells making and repairing DNA. Cancer cells need to make and repair DNA in order to grow and multiply.


How you have hydroxycarbamide

Hydroxycarbamide comes as 500mg capsules. Your doctor may ask you to take these in one dose or in several doses during the day. You swallow them whole with plenty of water. If you have trouble swallowing, you can empty the capsules into a glass of water and drink all of it straight away. Never leave any behind in the glass. You need to have the whole chemotherapy dose and if you leave some, someone else could drink it by mistake, which could harm them.

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

You usually have hydroxycarbamide as a course of several cycles of treatment. Sometimes there may be a break between cycles. The exact treatment plan depends on which type of cancer you have. To find out more about the way chemotherapy treatment is planned click on planning chemotherapy.

If you accidentally take too much hydroxycarbamide go to your nearest hospital immediately and take the drug package with you. 

If you forget to take a dose of the drug don't take the missed dose at all but take the next dose when it is due. Don't take a double dose to make up for the next dose.

The side effects associated with hydroxycarbamide are listed below. You can use the links (underlined) to find out more about each side effect. Where there is no link please see our cancer drugs side effects section, or click on search at the top of the page.


Common side effects

More than 10 in every 100 people have one or more of the side effects listed below.

  • An increased risk of getting an infection from a drop in white blood cells – it is harder to fight infections and you can become very ill. You may have headaches, aching muscles, a cough, a sore throat, pain passing urine, or you may feel cold and shivery. If you have a severe infection this can be life threatening. Contact your treatment centre straight away if you have any of these effects or if your temperature goes above 38°C
  • Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion
  • Bruising more easily due to a drop in platelets – you may have nosebleeds, bleeding gums after brushing your teeth, or lots of tiny red spots or bruises on your arms or legs (known as petechia). Let your doctor or nurse know straight away if you have this
  • A high temperature, chills and tiredness for a few hours after having the drug – taking paracetamol can help. Let your nurse know if these effects continue
  • Feeling or being sick is usually mild – ask your doctor if you can take your capsules in several doses as this may reduce the sickness
  • Loss of appetite
  • Constipation – your doctor or nurse may give you laxatives to help
  • Diarrhoea – you should drink plenty of fluids. If the diarrhoea becomes severe or continues you could become dehydrated so you should tell your doctor or nurse
  • Tummy (abdominal) pain
  • A sore mouth or lips
  • A skin rash or nail changes 
  • Tiredness and weakness (fatigue) during and after treatment – most people find their energy levels are back to normal from 6 months to a year after the treatment ends
  • Discomfort when passing urine – drink plenty of fluids to help prevent soreness and let your nurse know straight away if it occurs
  • Women may stop having periods (amenorrhoea) but this may only be temporary
  • Loss of fertility – you may not be able to become pregnant or father a child after treatment with this drug. Talk to your doctor about fertility before starting treatment if you plan to have a baby in the future. Men may be able to store sperm before starting treatment

Occasional side effects

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

  • Gout (swollen and painful foot joints) or kidney changes due to raised uric acid levels in the blood. You will have regular blood tests to check the levels. Drink plenty of fluids to help prevent gout and kidney changes
  • Confusion
  • Drowsiness – do not drive or operate machinery if you feel drowsy
  • Hair loss can happen for some people but the hair will grow back when the treatment ends
  • Disorientation and hallucinations (seeing or hearing things that are not there)
  • Headaches
  • Dizziness
  • Changes in lung tissue may cause a cough or breathlessness
  • Numbness or tingling in the fingers and toes – you may have trouble with fiddly tasks such as doing up buttons. This can start a few days or weeks after treatment and usually goes away within a few months of the treatment finishing
  • Low back pain or pain in your side
  • Soreness and irritation of the membranes of the vulval and vaginal area (when given with radiotherapy for cervical cancer treatment). Ask your doctor or nurse for painkillers and anaesthetic creams to reduce the soreness
  • An increased risk of leukaemia or a skin cancer if you take hydroxycarbamide long term for a myeloproliferative disorder. Don’t sit out in the sun and remember to cover up or use sun block on exposed skin. Your doctor will check your skin regularly

Rare side effects

Fewer than 1 in 100 people have the following effects.

  • Painful leg ulcers that go away slowly after the treatment ends
  • An allergic reaction to the drug – if you feel breathless or have any itching or swelling of the face, lips, tongue or throat, let your doctor or nurse know straight away and stop taking the tablets
  • A build up of bile in the blood which can cause itching, yellow skin, very dark urine and pale poo (stools or faeces)
  • Liver inflammation, causing flu like symptoms such as tiredness, a poor appetite, a high temperature, aching, feeling or being sick, and yellowing of the skin or eyes

Important points to remember

The side effects above 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)
  • 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. Some drugs can react together.

Pregnancy and contraception

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


Do not breastfeed during this treatment because the drug may come through in the breast milk.


Check with your doctor to see if drinking alcohol may harm you while having this treatment.


Immunisations and chemotherapy

You should not have immunisations with live vaccines while you are having chemotherapy or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG, yellow fever and Zostavax (shingles vaccine).

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your chemotherapy. It is safe to have the flu vaccine.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with vaccines you take by mouth (oral vaccines), but not many people in the UK have these now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.


More information about hydroxycarbamide

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: 30 June 2014