What causes red eye?

Itching and watering often fit an allergic pattern, while sticky discharge and eyelids that cling together can occur with conjunctivitis. A gritty, burning feeling may accompany dry eye or surface irritation. A tender bump at the eyelid edge can be a stye. A sensation that something is trapped may follow dust or another foreign body. Redness with marked pain, light sensitivity or blurred vision needs prompt clinical assessment because the deeper eye may be involved.

Do not rub the eye, and wash your hands before touching your face. Remove contact lenses until the eye feels normal and a clinician has advised that they are suitable again. A clean cool compress may soothe itching or swelling. Avoid sharing towels and eye makeup if discharge is present. Do not try to remove an embedded object or use someone else’s eye drops; a pharmacist or clinician can help choose a suitable option.

Seek urgent care for severe pain, a sudden change in vision, strong light sensitivity, an injury, chemical exposure, or a red eye while wearing contact lenses. Get prompt advice if redness is accompanied by headache, nausea, a very unequal pupil or significant swelling. Arrange an examination when symptoms keep returning, worsen, or do not settle with simple irritation measures.

Could the redness be allergy, infection, dryness or an injury? Should I stop contact lenses or any eye product? What signs would mean I need same-day review?