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Hydroxyurea for Sickle Cell Disease

Myleosuppressive Agent

Brand names:

Droxia®, Hydrea®, Siklos®

Often used for:

Sickle cell disease

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What is hydroxyurea?

Hydroxyurea is a medicine used to treat sickle cell disease. Hydroxyurea helps the body produce a special type of hemoglobin called hemoglobin F, or fetal hemoglobin. Hemoglobin F does not sickle. When you take hydroxyurea regularly, it helps your red blood cells stay round, flexible, and less likely to sickle. This medicine can decrease pain episodes, frequency of acute chest syndrome, and the need for blood transfusions.

Your care team will order blood tests to check blood counts.

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May be given as a liquid by mouth

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May be given as a capsule by mouth 


May be given as a tablet by mouth

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Possible side effects

  • Headache
  • Nausea 
  • Darkening of nails 
  • Thinning of hair (less common)


Not all patients who take hydroxyurea will have these side effects, and there might be others not listed. Some side effects can be severe. Please report any symptoms or side effects to your doctor or pharmacist. Find more information on side effects.

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Tips for patients and families

Be sure to discuss all questions and instructions with your doctor or pharmacist. 

  • Blood cell counts will need to be checked when taking this medicine. When you first start taking hydroxyurea labs will be more frequent.
  • Your team will use the blood cell counts to help decide if the dose needs adjusted.
  • It is important to take the medicine every day at about the same time each day. If you have difficulty taking the medicine talk to your medical team.
  • Sexually active patients should take steps to prevent pregnancy during treatment and for 6 months after treatment is complete. 

Hydroxyurea at home:

  • Give this medicine at the same time each day. 
  • This medicine can be taken with or without food.
  • Give this medicine with a full glass of water.
  • Wash your hands before and after giving this medicine.
  • Capsules: Swallow capsules whole. Do not open, crush, break, or chew. 
  • Liquid suspension: Your pharmacist may prepare an oral liquid to be given by mouth. Shake well before use. Measure the liquid medicine carefully using the syringes provided. Use each syringe only once and then throw it away in the trash. Do not wash or reuse syringes.
  • Tablets: The tablets may be cut on the score line based on the dose that is needed. If your child cannot swallow tablets, dissolve the tablet in a small amount of water and give the dose right away. Tablets are only used if your child is unable to use the liquid suspension or swallow capsules.
  • Store tablets and capsules at room temperature.
  • Store liquid hydroxyurea in the refrigerator.
  • Do not use the medicine past the expiration date.

Safe handling of hydroxyurea:

This medicine can pose a health risk to caregivers or others who come in contact with the medicine. Follow instructions for safe handling, storage, and disposal. 

  • Keep this medicine in the container it came in, tightly closed, and out of reach of children and pets.
  • Wear gloves while handling this medicine. Wash your hands right away if your skin touches the medicine.
  • Prepare a clean area where the drug can be handled safely. Keep it away from areas where food is prepared and away from air vents or fans.
  • Completely clean up any spills in the area where the medicine is prepared.

Find more information about handling and storing medicines at home.