Long-term study confirms hydroxyurea's sustained benefits for children with sickle cell disease

A medication that has long carried the shadow of its origins as a chemotherapy drug is proving itself, over years and in the real world, to be one of the most reliable tools doctors have for managing sickle cell disease in children. Hydroxyurea, taken once daily by mouth, reduces the number of times children end up in emergency rooms and cuts the days they spend hospitalized—and these benefits hold steady over time, according to a study of more than two thousand children published in Blood Advances.

The research, led by pediatric hematologists at Emory University and Children's Healthcare of Atlanta, stands out because it tracked actual patients in actual hospitals between 2010 and 2021, not volunteers in a controlled trial. Among 2,147 children with the most severe form of sickle cell disease, 1,240 had taken hydroxyurea, staying on it for an average of 5.1 years. The numbers were modest but consistent: children on the medication visited the emergency department 0.36 fewer times per year and spent 0.84 fewer days in the hospital per year compared to those who did not take it. For a child facing repeated crises—the sudden, severe pain that comes when misshapen blood cells block blood vessels—that difference accumulates.

Sickle cell disease is the most common inherited blood disorder in the United States, affecting roughly 100,000 people. The burden falls unevenly: it strikes one in every 365 Black or African American births and one in every 16,300 Hispanic American births. The disease warps red blood cells into a crescent shape, causing them to lodge in veins and arteries, starving organs of oxygen and triggering pain, organ damage, and life-threatening complications like acute chest syndrome, when blocked vessels choke off blood flow to the lungs.

Hydroxyurea works by reducing how often and how severely these crises happen. It also cuts the need for blood transfusions and eases anemia. The National Heart, Lung, and Blood Institute now recommends offering it to every child with the most severe variant starting between nine and twelve months of age. Yet the drug has carried a burden of doubt. It was originally developed as a chemotherapy agent, and that history has left lingering wariness among patients and families about whether it is truly safe for children over the long term. This study offers reassurance on that front: the medication's benefits persisted across years of use, and no new safety signals emerged.

But the research also surfaced a critical caveat. Improvements in hemoglobin levels—the measure of how well the medication corrects anemia—only showed up in children whose laboratory markers indicated they were taking the drug consistently, every single day. This points to a gap between what hydroxyurea can do in theory and what it does in practice. A child who misses doses will not get the full benefit. The researchers emphasized that doctors need to do more to help families understand that adherence is not optional; it is the difference between the medication working and it not working.

The study has limits. The researchers relied on laboratory markers to infer whether children were actually taking their pills—a proxy, not a direct measure. They lacked detailed data on some transfusions and on the cumulative damage from repeated pain crises. They hope future work will fill these gaps and include what patients themselves report about how the medication affects their lives outside the hospital. For now, though, the message is clear: hydroxyurea remains the most accessible and effective medicine available for children with severe sickle cell disease, and it keeps working. The challenge is making sure children actually take it.