It has activity against "P. ovale", "P. malariae", and severe "P. knowlesi". Artesunate + sulfadoxine/pyrimethamine for treatment of "P. vivax" is not recommended due to high rates of resistance. While artesunate is used primarily as treatment for malaria, there is some evidence that it may also have some beneficial effects in "Schistosoma haematobium" infection, but has not been evaluated in large randomized trials. Artesunate is used as the treatment of choice for severe malaria by the World Health Organization (WHO) over quinine. When given in the second or third trimesters of pregnancy, no artesunate-related adverse pregnancy outcomes have been reported. However, there is insufficient evidence regarding the safety of artesunate use in the first trimester of pregnancy. The WHO recommends that artesunate use for severe malaria in the first trimester should be based on the individual risks versus benefits. In absence of other viable treatment options, artesunate may be used. Artesunate is safe for use in children. Artesunate + sulfadoxine/pyrimethamine should be avoided in the newborns due to sulfadoxine/pyrmethamine effects on bilirubin. Parenteral artesunate dosing for treatment of severe malaria in children less than 20 kg should be higher than that of adults in order to increase exposure. When artesunate cannot be given orally or intramuscularly due to an individual's weakness or inability to swallow, rectal administration may be given as pre-referral treatment as long as parenteral administration is initiated after transfer to a more advanced facility. Artesunate may cause serious side effects including hemolytic anemia (a condition in which red blood cells are destroyed), and severe allergic reactions. Artesunate is generally safe and well tolerated. Artesunate-based regimens are less likely to cause vomiting and tinnitus than quinine plus anti-malarial antibiotic therapy. The best recognised adverse effect of the artemisinins is that they lower reticulocyte counts. This is not usually of clinical relevance. With increased use of I.V. artesunate, there have been reports of post-artesunate delayed haemolysis (PADH). Delayed haemolysis (occurring around two weeks after treatment) has been observed in people treated with artesunate for severe malaria.