Recently, the anti-malaria drug artesunate, which is widely used in the treatment of severe malaria, has been shown to be a highly effective inhibitor of HCMV in vitro. Artesunate exhibited similar antiviral activity (same micromolar range) to that of ganciclovir, while demonstrating no cytotoxicity. Importantly, its antiviral activity has been further demonstrated in vivo in a rat CMV model. No significant side effects were demonstrated in a number of pre-clinical and clinical studies, and artemisinin and its derivatives have been shown to be well-tolerated and safe in adults and children. Several million people have taken artemisinins to date, with no significant adverse or treatment-limiting effects being reported. Although neurotoxicity has been reported with supraphysiological doses in animals, it has not been documented in humans. Meta-analyses of malaria patients treated with artemisinins demonstrated that this drug class is safe. In rare cases, however, slight changes to haematology values have been seen, including a reduction in the number of reticulocytes as well as a slight increase in transaminase levels. These signs, however, do not generally give rise to any noticeable clinical manifestations. In rare cases, a slight but transient reduction in sinus heart rate has been observed. Abdominal cramps and mild diarrhoea have been reported at elevated doses.