Artesunate (AS) has been reported to be associated with mild gastrointestinal disturbances, dizziness and tinnitus although none of these associations are convincing. The only potentially serious adverse effect that has been reported with the artemisinin class of drugs in clinical trials is type I hypersensitivity reactions (about 1:3,000 patients). Transient reticulocytopenia, neutropenia, and elevated liver enzyme values have been reported but none have been clinically significant. The weight of evidence suggests these drugs have no significant adverse cardiovascular effects. A variety of clinical, neurophysiological, and pathologic studies in humans have not shown evidence of neurological toxicity. Because these drugs have not been evaluated extensively in early pregnancy in humans, they should be avoided in patients in the first trimester of pregnancy with uncomplicated malaria until more information is available (WHO guidelines 2006).