When 18th century British officers in India and other tropical areas drank a gin and tonic, they weren’t just relaxing. They were trying to fight off malaria. At the time, quinine powder — made from the bark of the cinchona tree — was used to prevent the disease, but it tasted bloody awful. So they took to mixing it with soda and sugar, creating tonic water — and mixing that tonic water with gin. The cocktail has remained popular over the years, but as medicine and science advanced, more effective ways of delivering anti-malarial drugs were developed. Still, even today, in some cases of malaria quinine is given by mouth and intravenously.