What causes allergic conjunctivitis?

When an allergen reaches the conjunctiva, the clear tissue over the white of the eye and inner eyelids, the immune system releases inflammatory chemicals. This causes itching, redness, puffy eyelids, and watery or stringy discharge, usually in both eyes. Allergic Rhinitis often occurs alongside it because the nose and eyes encounter the same airborne triggers. It is not spread from person to person. Rubbing can increase irritation and may damage the surface of the eye.

Avoid known triggers when practical, wash your hands after outdoor exposure, and use clean cool compresses for comfort. Do not share towels or use someone else's eye drops. A pharmacist or clinician can recommend suitable antihistamine or lubricating drops. Contact lenses may worsen irritation, so remove them until symptoms settle and follow professional advice about restarting them.

Seek urgent assessment for eye pain, light sensitivity, reduced or blurred vision, injury, a feeling that something is embedded, or thick discharge with marked swelling. One very painful or intensely red eye is not typical of simple allergy. Get emergency help for facial swelling with breathing difficulty.

Ask whether the pattern fits allergy or another eye problem, which drops are appropriate, and how to manage symptoms if you also have nasal congestion or sneezing. Mention contact-lens use, new cosmetics, and any change in vision.