Hydroxyurea is an oral medicine used to treat people living with sickle cell disease (SCD). It is considered a “first-line medicine” for many people with sickle cell disease because it can reduce pain crises and other complications, helping many people live longer and feel better.
Hydroxyurea is taken by mouth, usually once a day, as a capsule or liquid.
Hydroxyurea works by increasing the amount of fetal hemoglobin (HbF) in your blood. Fetal hemoglobin helps red blood cells stay round and flexible instead of rigid and sickle-shaped, allowing blood to flow more easily through vessels.
Because of this, hydroxyurea can:
Over time, these benefits may help protect organs and improve overall quality of life.
Hydroxyurea can be used in both children and adults with sickle cell disease — especially people with sickle cell anemia (HbSS or sickle β⁰-thalassemia).
It is often recommended for people who:
Many medical guidelines now support starting hydroxyurea early in life, even in young children, to prevent complications before they become severe.
Hydroxyurea is usually started at a low dose and gradually increased to find the safest and most effective level for each person.
Your healthcare team will schedule regular blood tests to:
Do not stop or change your dose on your own. Always speak with your healthcare provider first.
Many people who take hydroxyurea as prescribed experience:
Benefits may take several months to become noticeable, so taking the medicine consistently and attending lab appointments is important.
Like any medication, hydroxyurea can cause side effects. Most are mild and manageable with monitoring.
Possible effects include:
Studies following children and adults for many years show hydroxyurea is generally safe when properly monitored.
Regular blood tests help detect changes early so your provider can adjust the dose if needed. Serious side effects are uncommon when hydroxyurea is prescribed and monitored correctly.
People who may become pregnant should discuss family planning with their healthcare provider before starting hydroxyurea. Reliable contraception may be recommended because the medicine could affect a developing fetus.
If you are pregnant, planning pregnancy, or breastfeeding, your care team will help you weigh benefits and risks and discuss alternative options if needed.
You may find it helpful to ask:
Bringing a family member or writing questions down can help you remember the answers and feel confident in your treatment plan.
Hydroxyurea is a proven medicine that helps reduce complications and improve daily life for many people living with sickle cell disease.
It works by increasing protective hemoglobin, preventing sickling, and improving blood flow. When taken consistently and monitored regularly, the benefits often outweigh the risks.
Never stop hydroxyurea without medical advice — and always work closely with your sickle cell care team to get the most benefit from treatment.