At present, no specific treatment is available and management is usually supportive depending on whatever complication is most pronounced. Recently, hydroxyurea has received attention as a drug of choice for ameliorating SCD complications. Hydroxyurea's efficacy appears to depend on its ability to increase expression of fetal Hb, HbF-although other mechanisms may also be involved. HbF is not incorporated into HbS polymers and also serves to dilute the intracellular concentration of HbS, thereby reducing the tendency to polymerisation and sickling. Hydroxyurea is not without risks, however, being potentially teratogenic, with variable response, and also having issues of non-compliance-factors which restrict its use to more severely affected individuals.