After every swim, my nose is running for the next twelve hours. I'm not sure how, but my sinus system gets cleaned with chlorine every time. When I get out of the pool I even have a little trouble keeping my balance. Maybe the water gets in through my ears, in which case a cap might help. But nobody else swims with a cap, so maybe I'm doing something wrong. Or perhaps swimming is just a form of suffering that continues even after you're done.