As if hay fever weren’t enough of a hassle, the medications you use to control it could be messing with your diet. A recent study suggests that people who use prescription antihistamines olanzapine or risperidone are more likely than non-users to be overweight. That’s because antihistamines can stimulate your appetite and lead to overeating. No wonder you can’t keep your hand out of your coworker’s candy dish. Oral steroids, like prednisone, have also been known to cause water retention and weight gain. If you’ve been plagued with unexplained weight gain since starting your new medication, talk to your doctor about switching. Diet-friendlier bets include allergy shots and steroid-containing nasal sprays.