Hydroxycarbamide
Siklos (hydroxyurea) is a brand-name medication primarily used to reduce the frequency of painful crises in patients with sickle cell disease. It works by increasing fetal hemoglobin production, which helps prevent red blood cells from adopting the sickle shape that causes blockages in blood vessels.
Siklos is used to manage sickle cell disease by reducing painful crises through increasing fetal hemoglobin production.
Key facts at a glance
- RxNorm
- 1999309
- Generic
- Siklos
- Class
- brand-name
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Siklos is primarily indicated for reducing the frequency of painful crises and decreasing the need for blood transfusions in patients with symptomatic sickle cell disease. It may also be used in certain other conditions as determined by a healthcare provider.
Siklos contains hydroxyurea, which stimulates the production of fetal hemoglobin (HbF). Higher levels of HbF in red blood cells help prevent them from sickling and improve blood flow, reducing complications associated with sickle cell disease.
Siklos can cause bone marrow suppression, requiring regular blood count monitoring. It should not be used during pregnancy due to potential harm to the fetus. Patients should stay well-hydrated and report any signs of infection or unusual bleeding. Treatment should be supervised by a hematologist with experience in sickle cell disease management.
Official drug label
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This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 9, 2026. · Read our editorial policy