Conjunctivitis, commonly known as pink eye, is an inflammation of the conjunctiva that lines the white part of the eye. It is often caused by viral or bacterial infections, especially in children, or allergic reactions more common in adults. Symptoms include redness, swelling, increased tearing, discharge, irritation, and sensitivity to light. Home treatment involves warm or cold compresses, gently cleaning the eyelid, and avoiding contact lenses or makeup until healed. See a doctor for severe or prolonged symptoms, pain, or infection in young children.