Iced tea contains high concentrations of oxalates, a key contributor to kidney stones.
And the risk goes up in summer time, when many people may drink more iced tea than water.
Dr. John Milner, a urologist at Loyola University Chicago, says when heat settles in during summer, and people are advised to drink more fluids, they turn to iced tea drinks rather than water, because it is low in calories but has a better taste.
Kidney stones form from mineral and salt crystals in the urine. Most are very small and pass out of the body. But some can grow large enough to get stuck in the tubes leading from the kidneys to the bladder.
Men are 4 times more likely than women to develop kidney stones, and the risk rises even more after the age of 40.
Dr. Milner says water should be the #1 choice for staying hydrated. If you want to have iced tea, be sure to get lots of water, too.
Hot tea contains oxalates, too, but it's hard to drink enough to cause kidney stones.
85 per cent of the tea consumed in the U.S. is in iced form.