My daughter is on bactrim, which you also have to be very careful about being in the sun. We do sunscreen/hat, and avoid the rays at their strongest, noon time hour. We live in a cold part of the country so usually we don't see too many super strong sunny days. Some of the cute "rash guard" shirts for the beach have built in suncreen, my son without CF has one. I think they are pretty cool, better than a burqua<img src="i/expressions/face-icon-small-smile.gif" border="0"> We also encourage lots, lots fluids. Yesterday was very hot and I can't believe how much my daughter with CF can drink, Sh emust have drank 4 lemonades in less than 2 hours, when we were outside.