To keep foreign matter from invading ear canals. Earwax, or cerumen, is produced by glands in the outer ear to protect the inner ear from infection. The sticky substance prevents dust, dirt, and bugs from getting in. “Just leave it alone,” says Andrew Cheng, M.D., an ear, nose, and throat specialist at the Manhattan Eye, Ear and Throat Hospital. Ears are self-cleaning: The wax slowly moves up and out of the ears on its own, dries up, and flakes off or washes away when you shampoo your hair. If you’re a Q-tip addict, clean just the outside of your ears. “Ear canals are like dead-end streets,” Cheng says. “Q-tips just push wax further in.” You could also accidentally scratch your ear canal or even puncture the eardrum.