Hydroxycarbamide

Key facts

• Hydroxycarbamide, also called hydroxyurea, is a cytotoxic medicine that slows the growth of rapidly dividing cells. It is used in chronic myeloid leukaemia and other myeloproliferative blood disorders, and to reduce painful crises in sickle cell disease.
• It suppresses bone marrow production of blood cells. Regular full blood count tests are needed throughout treatment, more often when starting or changing dose, so your prescriber can adjust the dose or pause treatment if counts fall too low.
• It is cytotoxic and must be avoided in pregnancy, since it can harm the developing fetus; effective contraception is needed for anyone who could become pregnant or father a child during treatment.
• Seek urgent care for fever, sore throat, unusual bruising or bleeding, or a new skin ulcer that will not heal.

What hydroxycarbamide treats

Hydroxycarbamide treats chronic myeloid leukaemia and other myeloproliferative conditions such as essential thrombocythaemia and polycythaemia vera, where the bone marrow produces too many blood cells. In sickle cell disease, it raises the level of fetal haemoglobin, which reduces how often red blood cells sickle and lowers the frequency of painful vaso-occlusive crises and the need for blood transfusions.

How hydroxycarbamide works

Hydroxycarbamide blocks an enzyme called ribonucleotide reductase, which cells need to make the building blocks of new DNA. This slows the division of rapidly multiplying cells, including the abnormal blood cell production seen in myeloproliferative disorders. In sickle cell disease, it also increases fetal haemoglobin production, which interferes with the sickling process in red blood cells.

Before you take it

• Do not take hydroxycarbamide if you are pregnant or breastfeeding, or if you have severe bone marrow suppression already present.
• Tell your prescriber about other medicines that affect blood counts, and about any live vaccines you are considering, since these should be avoided during treatment.
• Handle capsules with care: do not open, crush or split them, wash your hands after handling, and keep them away from children and pregnant household members.
• Drink plenty of fluids, since adequate hydration supports kidney clearance of the drug.

Side effects

Common effects include low blood cell counts, nausea, mouth sores and skin changes such as darkening or dryness.

Stop and seek urgent medical care for any of these:

• Fever, sore throat, chills or other signs of infection.
• Unusual bruising, bleeding gums, or blood in urine or stool.
• A new leg ulcer or skin sore that does not heal.
• Shortness of breath, cough or chest pain.

Safety essentials

• Bone marrow suppression is the defining risk of hydroxycarbamide. Regular full blood counts are mandatory for as long as you take it, and your dose is adjusted or paused based on the results.
• It is a cytotoxic drug: avoid it in pregnancy, use effective contraception during treatment, and handle capsules with clean, dry hands rather than opening or crushing them.
• Long-term use has been linked to skin cancers, so protect your skin from the sun and have new or changing skin lesions checked promptly.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.