Gin as medicinal treatment has been used for several hundred years. The modern day spirit known as gin was developed by Dutch physician Fransciscus Sylvius in the 16th century and was sold in pharmacies as a diuretic and a treatment for gout, gallstones, and stomach ailments.
Gin is distilled spirits flavored or redistilled with juniper berries. Juniper berries have been known since ancient times to have pharmacological properties. Juniper-laced concoctions were used as a treatment of plague (rather unsuccessfully) from the 11th century on.
Gin was also the base spirit for quinine (“tonic”) used as prophylaxis against malaria by non-indigenous peoples before the advent of modern day chemoprevention. Hence the gin and tonicÂ highball cocktail.