Good ol quinine, malaria prophylactic and tasty beverage all in one. While it would take huge amounts of tonic water everyday to get an antimalarial benefit, some people have found that drinking tonic water helps reduce chronic muscle cramps. While the side affects of too much quinine can include temporary deafness and renal failure the only side effects I've had are cool refreshment.
Quinine also absorbs UV light and will fluoresce under a UV light, its so sensitive you can see it fluoresce even in direct sunlight.
The one on the left with the cool blue tinge is the Indian Tonic water. The one on the right is plain water for comparison. Both have ice because I've been out gardening and I'm not going to drink warm tonic water for the sake of demonstrating fluorescence.