Pinkeye is a common eye infection that makes the white part of your eye turn pink or red. Doctors call it conjunctivitis, but most people know it by its more descriptive name. The infection irritates the thin, clear tissue covering your eyeball and the inside of your eyelids, causing inflammation that makes your eye look distinctly pink.

Pinkeye spreads incredibly easily, especially in schools. If you touch your infected eye and then touch a doorknob, pencil, or basketball, the next person who touches that object and rubs their eye might catch it too. That's why nurses send kids with pinkeye home and tell them not to return until it's no longer contagious. Bacterial pinkeye often produces a crusty yellow discharge that can make your eyelids stick together overnight, while viral pinkeye tends to be watery and often comes with a cold.

Not all pinkeye is contagious. Sometimes allergies or irritants like chlorine or smoke can cause similar symptoms without any infection. But if your eye turns pink, feels itchy or gritty, and produces discharge, a doctor can determine what type you have and whether you need antibiotic drops. Most cases clear up within a week or two.