Hydroxycarbamide Hydrea, Siklos, Xromi

Last updated by Peer reviewed by Sid Dajani
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You will be prescribed hydroxycarbamide by a specialist doctor.

Please keep your regular clinic appointments so that your doctor can check on your progress. You will need to have regular blood tests.

If you think you are getting an infection or if you have a high temperature (fever), please contact your doctor for advice straightaway.
Type of medicineA cytotoxic medicine
Used forSome cancers; polycythaemia rubra vera; sickle cell disease
Also calledHydroxyurea/ Droxia® (in US); Hydrea®; Siklos®; Xromi®
Available asHydrea® capsules, Siklos® tablets, Xromi® oral liquid medicine

Hydroxycarbamide is prescribed for a number of different conditions. There are multiple brands of the medicine available. The brand of hydroxycarbamide capsules called Hydrea® are prescribed for people with some types of cancer, and also for people with a condition known as polycythaemia rubra vera. The brand of hydroxycarbamide tablets called Siklos® is prescribed for people with sickle cell disease. It is important that each time you collect a new supply of medicine, you make sure it is the same brand of hydroxycarbamide that you have had before.

The types of cancer which can be treated with Hydrea® capsules include chronic myeloid leukaemia (CML) and cancer of the cervix. In cancer, certain cells in the body grow and multiply too quickly. Anti-cancer medicines like hydroxycarbamide work by interfering with the growth of the cancer cells.

Polycythaemia rubra vera is a disorder where the bone marrow makes too many blood cells. This leads to an abnormally high number of red blood cells being in your blood, making it 'thicker' than normal. Hydrea® capsules work by slowing down the production of the red blood cells.

Siklos® tablets are prescribed to ease painful conditions associated with sickle cell disease. In this condition, red blood cells have a tendency to go out of shape and can then block blood vessels, causing pain. Hydroxycarbamide can help to reduce these episodes of pain by helping to prevent the blood cells from going out of shape.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking hydroxycarbamide it is important that your doctor knows:

  • If you are pregnant or breastfeeding.
  • If you have any problems with the way your liver works or how your kidneys work.
  • If you have any leg ulcers.
  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine.
  • Before you start the treatment, read any printed information you have been given by your doctor and the printed manufacturer's leaflet from inside the pack. These will give you more information about hydroxycarbamide and will provide you with a full list of the side-effects which you may experience from taking it.
  • Hydroxycarbamide will be given to you by a specialist doctor who is experienced in treating your condition. Your doctor will calculate what dose is right for you, and will tell you how much to take and how often to take it. You may be asked to take a dose each day, or every third day. Your dose will be printed on the label of the pack to remind you about what the doctor said to you, but if you have any concerns, contact your doctor or hospital clinic for advice.
  • If you are taking Hydrea® capsules and you have difficulties swallowing, you can stir the contents of the capsules into a glass of water and then drink it straightaway. If you do this, be careful not to get the contents of the capsule on to your skin. You can take Hydrea® capsules either with or without food.
  • Siklos® tablets should preferably be taken in the morning before breakfast. If you have difficulty swallowing, you can allow the tablet to disintegrate in a little water before swallowing it. You can mask any bitter taste by adding a drop of honey or mixing in a small amount of food.
  • An oral liquid medicine called Xromi® is available for children and people who have difficulty swallowing. Use the oral syringes provided to measure the dose accurately. Take the dose with or just after a meal and drink a glass of water after each dose.
  • You must try to keep your regular appointments with your doctor or hospital. This is so your doctor can check on your progress. You will need to have regular blood tests and check-ups during your treatment with hydroxycarbamide. The blood tests are important as a way of monitoring your treatment, and also to check that your kidneys and liver are working properly.
  • It is important that you do not get pregnant while you are taking hydroxycarbamide. Make sure you have discussed with your doctor which types of contraception are suitable for you and your partner. Many anti-cancer treatments are associated with reduced fertility (particularly in men), so you may also want to ask your doctor for family planning advice if you would like to have children.
  • While you are taking hydroxycarbamide and for six months after you have stopped the treatment, do not have any immunisations (vaccinations) without talking to your specialist doctor first. Hydroxycarbamide lowers your body's resistance and there is a risk that you will get an infection from some vaccines.
  • Rarely, people who take hydroxycarbamide over a long period of time can develop skin cancer. You can reduce the risk of this by protecting your skin from the sun by wearing suitable clothing and using a sunscreen with a high sun protection factor (SPF) of at least 15.

Medicines like hydroxycarbamide which can be used to treat cancer can have a number of side-effects, some of which you might not experience until several days or weeks after starting the medicine. They can lower the number of white cells in your blood, which increases the risk of you getting an infection. While you are taking hydroxycarbamide you should take precautions to reduce the risk of getting an infection - you can do this by avoiding being with people who you know have an infection. If you think you are getting a sore throat or if you have a high temperature, please let your doctor know as soon as possible so that you can get some treatment straightaway.

Your doctor will discuss with you the possibility of unwanted side-effects from your treatment. The table below contains some of the most common side-effects associated with hydroxycarbamide, although not everyone experiences these. You will find a full list in the manufacturer's information leaflet supplied with your treatment. Please let your doctor know if you experience any of the following:

Very common hydroxycarbamide side-effects (these affect more than 1 in 10 people)
What can I do if I experience this?
Decreased number of white or red blood cells, or plateletsLet your doctor know if you are getting a sore throat or if you have a high temperature. If you notice any unusual bleeding or bruising, contact your doctor straightaway
Feeling sick (nausea), loss of appetite, diarrhoea or constipation, tummy (abdominal) pain, indigestionStick to simple meals. If troublesome, let your doctor know
Sore mouthAsk your doctor for advice on a suitable remedy
Skin reactions and nail disordersAsk your doctor for advice
Headache, chills, high temperature (fever)Ask your doctor or pharmacist to recommend a suitable painkiller

If you experience any other symptoms which you think may be due to hydroxycarbamide, speak with your doctor or pharmacist for further advice.

  • Keep all medicines out of the reach and sight of children.
  • Store in original containers in a cool, dry place, away from direct heat and light.
  • The oral liquid medicine should be stored in a refrigerator and used within 12 weeks of opening.

If you buy any medicines check with a pharmacist that they are safe to take with your prescribed medicines.

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

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