[rwfok]

My tonic water does, in fact, contain quinine. It is the last listed ingredient as quinine hydrochloride (had to fire up the magnifying app).

[Aquamarine]

Have a friend that drinks tonic water every night for muscle cramps. Also takes pills called Leg Cramps, both have quinine and keep the cramps at bay.

[Tuscaloosa Goldfinch]

My tonic water contains quinine also. Fever Tree is the brand.