[3] In areas of Africa with moderate to high rates of malaria, three doses are recommended during the second and third trimester of pregnancy.
[4] Side effects include diarrhea, rash, itchiness, headache, and hair loss.
[9] However, it is recommended by the World Health Organization (WHO) for seasonal preventative use in children when combined with amodiaquine.
[6] Pyrimethamine serves as a selective inhibitor of protozoal dihydrofolate reductase, hence preventing the synthesis of tetrahydrofolate — the active form of folate.
[6] A great degree of synergy occurs between the two drugs due to their inhibition of two different steps in the biosynthesis of tetrahydrofolate.