Severe systemic effects of Merrem's hump-nosed viper bite.

To report unpredictable severe systemic effects of hump-nosed viper envenomation.Medical unit, General hospital, Anuradhapura.The clinical outcome of seven patients bitten by Merrem's hump-nosed viper were monitored until recovery or death. Limited autopsies were performed on the latter. Offending snakes were positively identified by medical officers and in one instance by a herpetologist.Merrem's hump-nosed viper bites, caused an array of potentially fatal systemic manifestations. One patient developed neurological effects, severe Raynaud's syndrome leading to ascending gangrene of distal limbs and adult repiratory distress syndrome (ARDS), in addition to the known complications of severe renal cortical necrosis and haemostatic dysfunction. Two patients who developed acute renal failure and prolonged coagulopathy recovered completely. The combination of extensive renal cortical necrosis, disseminated intravascular coagulation, and ARDS proved fatal in three.