If you get that problem, OC, the dr will need to write you an rx for an oral medicine. There might be something you can buy OTC, but I'm not sure what. Your pharmacist might be able to help you there if you get that problem. It's not extremely painful, but it's VERY irritating and looks awful (my ds used to get them quite frequently-he's taken a lot of antibiotics in his 6 1/2 years!).