Breakthrough bleeding
“I think this is the side effect that drives women crazier than any other side effect,” says Dr. Hutcherson, because it’s so unpredictable. Taking the Pill at precisely the same time every day may help. The bleeding occurs specially with shots, the mini-Pill, and the implant—the progestin-only methods—as the lining of the uterus is so thin that it sometimes sloughs off a little bit.