A popular over-the-counter laxative used to flush out patients’ bowels before procedures such as colonoscopies has caused serious kidney damage and even death, a series of lawsuits filed across the country alleges.

The lawsuits target Fleet Phospho-soda, made by C.B. Fleet Co. Inc. of Lynchburg, Va. More than 50 have already been filed in at least 20 states, Stephen Foley, one of the lawyers involved in the litigation, said Thursday. Nine of them were filed this week in federal court in Minnesota.