Hydroxyurea causes an increase in the amount of fetal (or baby) hemoglobin (hemoglobin F) in the red blood cells. Fetal hemoglobin blocks the effects of the sickle hemoglobin in the red blood cell. A research study in adult patients with serious problems from sickle cell disease showed that treatment with hydroxyurea led to fewer pain crises, fewer episodes of acute chest syndrome (pneumonia), fewer hospitalizations and less need for transfusions.

What is Involved in Hydroxyurea Treatment?

When patients are on this medication, they must be very compliant – take the medication every day as instructed, or it won’t work well. This medication should be handled with care, and people who are not taking this medicine should be careful to avoid touching it. To help you remember to take your medicine, try to get into the habit of taking it at the same time each day. 

To check for the effects of hydroxyurea, your blood count will be checked every month to make sure that there are no problems with your blood counts like a drop in white blood cells (the cells that fight infection) or fall in platelets (cells that stop bleeding) or worsening of anemia. Blood counts will be taken each month as long as you are taking hydroxyurea. Depending on your blood count results and how you are responding to treatment, your dose of hydroxyurea may be increased gradually.

Since hydroxyurea does not start working right away, we ask you to take the drug for at least six months to see if its working unless you are having bad side effects (bad reactions) to the drug.

What are the Risks of Taking Hydroxyurea?

At high doses, hydroxyurea can cause suppression of the bone marrow (low blood counts) leading to increased risk of anemia, infections or bleeding. Mild liver and kidney damage have been reported in adult patients taking hydroxyurea for other conditions. This has not occurred in sickle cell patients taking hydroxyurea. In adults treated with hydroxyurea for certain chronic blood diseases, there is a worry of an increased risk of leukemia, but this has not been proven.

Hydroxyurea can cause nausea or vomiting, thinning of the hair, or darkening of the nails. It is possible that unexpected side effects might occur at any time.

Pregnant women should not take hydroxyurea. The effects of hydroxyurea on an unborn baby are probably harmful. You should not become pregnant or father a baby while you are taking hydroxyurea. You should not nurse your baby while on hydroxyurea. You need to take safety measures to prevent pregnancy (such as not having sexual intercourse, using barrier methods such as diaphragm or condom, taking birth control pills, using an IUD, etc.) while you are receiving this drug or treatment. You should call the Sickle Cell Clinic nurses or other providers if you become pregnant or have any questions or concerns.