The cocktail was introduced by the army of the British East India Company in India. In India and other tropical regions, malaria was a persistent problem. In the 1700s Scottish doctor George Cleghorn studied how quinine, a traditional cure for malaria, could be used to prevent the disease. The quinine was drunk in tonic water, however the bitter taste was unpleasant. British officers in India in the early 19th century took to adding a mixture of water, sugar, lime and gin to the quinine in order to make the drink more palatable, thus gin and tonic was born. Soldiers in India were already given a gin ration, and the sweet concoction made sense. Since it is no longer used as an antimalarial, tonic water today contains much less quinine, is usually sweetened, and is consequently much less bitter.
Gin and tonic is a popular cocktail during the summer. A 2004 study found that after 12 hours, “considerable quantities (500 to 1,000 ml) of tonic water may, for a short period of time, lead to quinine plasma levels at the lower limit of therapeutic efficacy and may, in fact, cause transitory suppression of parasites”. This method of consumption of quinine was impractical for malaria prophylaxis, as the amount of drug needed “can not be maintained with even large amounts of tonic”. The authors conclude that it is not an effective form of treatment for malaria.