[entropy12]

A quart a week is significantly better than no quarts in a week. Quinine builds up in your system with regular use. No need to overdose.

[steve86]

One quart is entirely insignificant. The new-style tonic water has only something like 1/18th the quinine of the old.

In the United States, the US Food and Drug Administration (FDA) limits the quinine content in tonic water to 83 ppm[3] (83 mg per liter if calculated by mass), while the daily therapeutic dose of quinine is in the range of 500–1000 mg,[4]