Nipple discharge—unless you're breastfeeding, probably an unwelcome surprise. But according to Mary Claire Haver, M.D., an ob-gyn at the University of Texas Medical Branch, it's not necessarily a sign of a problem. It's actually very common. Roughly 75 percent of women in their reproductive years will experience nipple discharge, she says. And in the vast majority of cases, it's totally benign. In fact, your workout routine may be to blame.
"One common cause of nipple discharge is excessive nipple stimulation, so I'll ask patients if they recently started a new exercise routine that involves a lot of jumping or bouncing," says Haver. "If they're not wearing a good sports bra, that can cause a lot of rubbing on the nipple, which can cause discharge." She also asks women if they've recently started a new relationship; their breasts may be getting some extra attention while they're in the honeymoon phase. In these cases, upgrading your sports bra (find the best one for your cup size with these tips) or telling your partner to take it easy on your top half should be enough to resolve the problem.
Certain medications can also stimulate discharge, including mood stabilizers and even some herbal meds, specifically ones containing fenugreek. (How to Buy Herbal Medicine Safely)
Still, discharge could signal something serious, like breast cancer, so you should call your doc to make sure. That's especially important if the discharge is green, blue, bloody, or only coming from one breast or from multiple spots on the nipple. But you probably don't need to worry if the liquid is white or straw-colored, is occurring from both breasts, is coming out of the center of the nipple, can be expressed (meaning if you squeeze your nipple, discharge comes out), and is occurring without pain. Again, call your doc just in case, but don't freak.