Droxia (hydroxyurea)

The foundational treatment for sickle cell disease. Stimulates production of fetal hemoglobin, which prevents red blood cells from forming the rigid sickle shape that causes pain crises and organ damage.

Hydroxyurea turns back on the body's ability to make fetal hemoglobin, a type of hemoglobin that babies produce before birth. Fetal hemoglobin prevents the abnormal sickle hemoglobin (HbS) from clumping together and deforming red blood cells. It also reduces white blood cell and platelet counts, which helps prevent the blood vessel blockages that cause pain crises.

Hydroxyurea for sickle cell disease (Droxia, Siklos) carries a boxed warning for severe bone marrow suppression (low blood counts) and for cancer, because hydroxyurea is carcinogenic. Blood counts are checked at the start and throughout treatment, sun protection is advised, and patients are monitored for cancers. Other common effects include infections, headache, dry skin and stomach upset. Can cause birth defects and should not be used during pregnancy. The label also warns about breakdown of red blood cells (hemolytic anemia), skin ulcers and gangrene from blood vessel inflammation, serious infection from live vaccines, pancreatitis, liver damage and nerve damage when taken with certain HIV medicines, lung inflammation and scarring (including fatal cases), enlarged red blood cells, and falsely high results on some lab tests and on some continuous glucose monitors, which can lead to low blood sugar if those readings are used to dose insulin. Long-term use is generally well tolerated with proper monitoring.

Taken by mouth once daily as a capsule or tablet. Starting dose is typically 15 mg/kg/day in adults (20 mg/kg/day for children on Siklos), gradually increased to a maximum tolerated dose of up to 35 mg/kg/day based on blood counts. Requires regular blood count monitoring.

Yes, Hydroxyurea (Droxia) is FDA approved (1998) for the treatment of Sickle Cell Disease.

Hydroxyurea has been used for sickle cell disease since its FDA approval in 1998, giving it over 25 years of clinical experience. It was originally developed as a cancer drug in the 1960s and is now listed as a WHO essential medicine for SCD.

Current guidelines recommend considering hydroxyurea for most sickle cell disease patients starting in early childhood, typically from 9 months of age. Early treatment can help prevent organ damage before it accumulates. FDA approval depends on the product: Xromi oral solution is approved for children 6 months and older, Siklos tablets for adults and children 2 and older, and the Droxia capsule label says safety and effectiveness in children have not been established. All 3 are approved for sickle cell anemia with repeated moderate to severe pain crises.

No. Hydroxyurea can cause birth defects and should not be used during pregnancy. Women of childbearing potential should use effective contraception during treatment and discuss family planning with their doctor before and during therapy.

Regular complete blood count monitoring is required because hydroxyurea can lower blood cell counts. The label calls for blood counts every 2 weeks when starting and adjusting the dose; once a stable dose is reached, your hematologist will set a longer interval.

Yes. Hydroxyurea can be used alongside crizanlizumab (Adakveo) and L-glutamine (Endari) for patients who continue to have crises on hydroxyurea alone. It is the foundation of SCD therapy on which other treatments are added.

Yes. Hydroxyurea is available as a generic medication with multiple manufacturers, making it significantly more affordable than newer branded sickle cell treatments. Brand names include Droxia and Siklos.

The landmark Multicenter Study of Hydroxyurea (MSH) in 1995 showed hydroxyurea reduced painful crises by 44%, hospitalizations by 58%, and the need for blood transfusions by over a third. Decades of follow-up confirm long-term safety and survival benefit.