I DONATE TWO OR THREE TIMES A YEAR: Frequent blood donations safe for some, but not all. “Blood donors give about a pint of blood each time, explained Murphy, who co-authored an editorial published with the study. That depletes them of about 200 to 250 milligrams of iron, he said. And it takes the average donor about six months to fully recover those iron stores, if no supplements are used. That window shrinks to around 90 days if a donor takes a standard daily iron pill, according to Murphy. Yet the currently recommended blood-donation intervals do not reflect that.”