Allergic conjunctivitis is inflammation of the conjunctiva — the thin membrane covering the white of the eye and inner eyelids — triggered by immune reactions to substances like pollen, dust mites, animal dander or cosmetics. It commonly causes itching, redness and watery eyes. This page summarizes likely causes, common complaints, typical diagnostic approaches and everyday measures that can help reduce symptoms and exposure.
What it is and common triggers
Allergic conjunctivitis occurs when the immune system reacts to airborne or contact allergens. Typical triggers include seasonal pollens, house dust mites, pet dander and ingredients in cosmetics or eye drops. Immune mediators such as histamine cause blood vessel dilation and fluid production on the eye surface, producing the characteristic itching and redness. People with other allergic tendencies (hay fever, eczema) often experience it more frequently.
Typical symptoms and daily impact
Symptoms usually include intense eye itching, redness, tearing, a burning or gritty sensation and sometimes mild eyelid swelling. Symptoms may fluctuate with exposure — for example, worsening during high pollen seasons — and can interfere with sleep, concentration and outdoor activities. Contact lens wearers may notice increased discomfort.
Diagnosis and who to see
Diagnosis is based on a medical history and eye examination by an ophthalmologist (eye specialist). The exam focuses on the conjunctiva and ocular surface; in some cases, an allergy specialist (Allergy & Immunology) may be involved to identify specific triggers using skin prick tests or blood tests. If symptoms suddenly worsen or there are signs of decreased vision, severe pain, or intense light sensitivity, seek urgent medical attention.
Practical prevention and daily measures
Reducing exposure to known allergens often lessens symptoms. Measures include limiting time outdoors during high-pollen days, keeping windows closed, using dust-mite–proof bedding, washing hands and face after being outside, keeping pets out of sleeping areas and avoiding rubbing the eyes. Maintain contact lens hygiene and pause lens wear if eyes feel irritated. For severe or rapidly worsening symptoms, follow local emergency guidance.