Pink eye is a common eye condition that causes redness and inflammation of the conjunctiva, the thin membrane that lines the inside of the eyelids and covers the whites of the eyes. This condition is also known as conjunctivitis. However, there are other synonyms for pink eye, including sore eyes, eye flu, pinkeye, and madras eye. The symptoms of pink eye can vary, but typically include redness, itchiness, and discharge. It can be caused by a bacterial or viral infection, allergies, or irritation from contact lenses and other irritants. Treatment options range from antibiotic eye drops to cold compresses and rest.