The 10 Biggest Summer Myths—Busted!

1. Going In and Out of Air-Conditioned Buildings Can Make You Sick

Big temperature swings don't make you vulnerable to colds. If you feel congested or start sniffling, it's likely due to summer allergies, says pulmonologist Neil Schachter, M.D., author of The Good Doctor's Guide to Colds and Flu. "People who have allergies—even small sensitivities—may be affected when moving from a clean-air environment into one that's full of Mother Nature's irritants," he says.

2. Don't Drink from the Garden Hose—It's Filled with Germs
"No germs live specifically in garden hoses," says Charles Gerba, Ph.D., a professor of environmental science at the University of Arizona. But run the water for a few minutes anyway, to rinse off the hose nozzle—you never know what it's been sitting in.

3. Ease a Jellyfish Sting by Peeing on It
This idea was made popular by a classic episode of Friends. It's just not true. Urine hasn't been proven to curb the hurt. What has: vinegar. "Its acidity is believed to inactivate the stingers and diminish the pain," says Stanford University School of Medicine