Study	Reason for exclusion
Biswas 2014	This is randomised study, available in abstract only, which evaluated the efficacy of hydroxyurea against valproic acid among transfusion dependent Hb E/ß thalassaemia patients.
Elalfy 2013	This 15‐month trial randomised young people with ß thalassaemia into 2 groups, either hydroxyurea alone or hydroxyurea in combination with erythropoietin. Erythropoietin induces production of red blood cells.
Karimi 2010	This is a randomised controlled trial carried out over 6 months to assess the effect of combination therapy of hydroxyurea with L‐carnitine and magnesium chloride. The participants received either hydroxyurea alone, hydroxyurea and L‐carnitine, hydroxyurea and magnesium chloride, or a combination of all 3 drugs. Both hydroxyurea and L‐carnitine are foetal haemoglobin enhancers, while magnesium chloride is known to stabilize erythrocytes' membrane and morphology.