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What are the aims of this leaflet?

This leaflet has been written to help you understand more about hydroxycarbamide. It tells you what it is, how it works, how it is used to treat skin conditions, and where you can find out more about it.

What is hydroxycarbamide and how does it work?

Hydroxycarbamide, formerly known as hydroxyurea, affects cells that are dividing rapidly, such as the skin cells in psoriatic plaques and the blood cells in the bone marrow. It is mainly used for cervical and blood cancers, but is also used to treat psoriasis. It is known as a ‘cytotoxic’ medicine, meaning that it interferes with cell growth.

How long has hydroxycarbamide been available?

Hydroxycarbamide has been available to treat psoriasis since 1965.

Which skin conditions are treated with hydroxycarbamide?

Hydroxycarbamide is used for severe plaque psoriasis that is not responding to other treatments.

How long will I need to take hydroxycarbamide before it has an effect?

Most patients notice an improvement, which starts after a few weeks and reaches a maximum after 6-8 weeks.

What dose of hydroxycarbamide should I take?

Your doctor will advise you. It is available in 500 mg capsules and you may be asked to take 1 to 3 capsules daily.

How long will I need to take hydroxycarbamide?

If it is found to be effective, hydroxycarbamide can be taken for months or years. The treatment must be monitored carefully by your GP or consultant.

What are the possible side effects of hydroxycarbamide?

As hydroxycarbamide affects cell growth, it can affect the way that blood cells are made in the bone marrow. Hydroxycarbamide can therefore occasionally cause side effects such as:

  • An increased risk of getting an infection due to a drop in white blood cells. White blood cells are part of the immune system which fight infections

  • Feeling of breathlessness or tiredness due to a drop in red blood cells. Red blood cells carry oxygen around the body

  • An increased risk of bleeding and bruising due to a drop in blood clotting cells

  • Hair loss, but the hair will grow back when the treatment ends

  • Loss of appetite, loose stools or hard stools

  • Skin pigmentation (mild/yellow grey)

  • Liver inflammation (rare)

  • Kidney dysfunction (rare, and less likely if you drink plenty of water)

  • Drug reaction (drug-related lupus) - light sensitivity, muscle and joint pains

  • Leg ulcer

  • Gout

  • There may be a small increase in the risk of skin cancer, so you should protect your skin from the sun during your treatment.

You must contact your doctor immediately in the following circumstances:

  • An infection, a severe sore throat, fever or mouth ulcers (a low white blood cell count increases the risk of infection)

  • Tiredness and breathlessness (a low red blood cell count – anaemia – can cause this)

  • Unexplained bruising or bleeding (a low platelet count increases the risk of bleeding and bruising)

  • If you are in contact with people with chickenpox or shingles

How will I be monitored for the side effects of hydroxycarbamide treatment? 

Regular blood tests are required during the period that you are taking hydroxycarbamide. It is important that you have these tests. Usually you need weekly visits to the doctor or hospital until you are on the effective dose and then every 1-3 months thereafter. All patients taking hydroxycarbamide develop temporary macrocytosis (large red blood cells) which is identified on blood tests but not harmful in any way.

You must report any illness to your doctor straightaway.


The BAD Biologic Interventions Register (BADBIR)

If you have been prescribed hydroxycarbamide for treatment of your psoriasis, you may be asked to take part in the national biologics register. This register is to compare the safety of different treatments for psoriasis and to see how well they work. It was set up to monitor some new treatments for psoriasis called biological treatments. The register will give doctors information on how best to use the treatments available for moderate to severe psoriasis. No information will be passed to the register without your informed consent.


Does hydroxycarbamide affect fertility or pregnancy?

You must not become pregnant whilst on hydroxycarbamide, and for at least 2 months after stopping treatment. If you are thinking about starting a family talk to your doctor or consultant for alternative treatments. Do not handle the capsules if you are pregnant or breast feeding, or if you are a man hoping to father a child. Do not breastfeed if you are taking hydroxycarbamide.

Can I take other medicines at the same time as hydroxycarbamide?

Always ask your doctor or pharmacist before taking any new medicine.

  • Combining hydroxycarbamide with some medications such as methotrexate or cytarabine can result in suppression of the cells in the bone marrow and therefore requires close supervision.

  • You should avoid immunisation injections with any of the live vaccines such as polio and rubella (German measles). Inform your doctor or nurse that you are taking hydroxycarbamide prior to any vaccinations. Flu vaccines and Pneumovax are safe and recommended; however, the new nasal flu vaccination is live and should not be given with hydroxycarbamide (see Patient Information Leaflet on Immunisation.

Where can I find out more about hydroxycarbamide?

If you want to know more about hydroxycarbamide, or if you are worried about your treatment, you should speak to your doctor or pharmacist. This information sheet does not list all the side effects of hydroxycarbamide. Full details are on the drug information sheet enclosed in your prescribed box of hydroxycarbamide.

For details of source materials use please contact the Clinical Standards Unit (

This leaflet aims to provide accurate information about the subject and is a consensus of the views held by representatives of the British Association of Dermatologists: individual patient circumstances may differ, which might alter both the advice and course of therapy given to you by your doctor.

This leaflet has been assessed for readability by the British Association of Dermatologists’ Patient Information Lay Review Panel






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