What does tonic water contain that could help with leg cramps?

Tonic water contains quinine, which is an anti-malarial medicine. It has a bitter taste and tonic water is a popular cocktail mix. It is also thought that quinine helps with leg cramps and restless leg syndrome. Quinine is extracted from the bark of the Cinchona tree. These trees are native to the tropical Andean forests and in Western South America. It is also found in some islands of the Caribbean and Western parts of Africa.

Two to three ounces is the recommended dose to be taken before bed. This is, simply put, a home remedy without scientific studies to back the claim. Caution is advised, though, as quinine has several adverse side effects. It can cause confusion, nervousness, cramps and ringing in the ears.