[petecox]

It's commonly used for malaria. A related '-quine' is the active ingredient of Gin and Tonic.

[Udik]

The active ingredient of gin & tonic is definitely alcohol :)

[IAmEveryone]

Tonic was invented to make quinine palatable to British soldiers in India. About three minutes into the scheme, someone added gin.

So quinine is indeed arguably the original “active” ingredient, sugar was second (to mask the flavor), and alcohol “let’s just pretend this isn’t happening” was third.

[elric]

Is this the same malaria drug that can cause depression and lead to suicidal thoughts?