This is a bit more sensible
Quote: "It's a myth that Tonic Water itself was intended as a cure for malaria, or even as preventive medicine.
At 27 mg quinine per 8 oz (240 ml), the amount of quinine in Tonic Water is reputedly too small to act as a drug, or even to interact with other drugs.
Quinine is used in malaria treatment. Quinine tablets contain anywhere from 200 to 350 mg of quinine. A sample treatment is 2 x 300 mg quinine tablets every 8 hours for 7 days. To equal that treatment level by drinking Tonic Water, you'd have to drink an awful lot of it -- every 8 hours, you'd have to drink about 22 8 oz cups of it to replace the 2 x 300 mg tablets. If you drank all that mixed with gin, after the hospital had treated your malaria they might check you into the Betty Ford.
Quinine is also used to prevent night-time leg cramp in bed."