The American College of Physicians has issued a new set of recommendations to prevent recurrent kidney stones.

Published in the Annals of Internal Medicine, the guidelines recommend the following:

Patients with a history of kidney stones should be encouraged to increase their fluid intake, with a goal of producing at least 2 liters of urine a day.
In patients with active disease in whom higher fluid intake is not sufficient, treatment with a thiazide diuretic, citrate, or allopurinol is recommended.
Patients should also be encouraged to avoid colas, which are acidified with phosphoric acid. The recommendation does not apply to fruit-flavored soft drinks, which are often acidified with citric acid.

Annals of Internal Medicine article