Allergic Conjunctivitis

Key facts

• Allergic conjunctivitis is inflammation of the conjunctiva, the thin membrane covering the white of the eye, caused by an immune reaction to airborne allergens.
• Common triggers are dust mites, grass and tree pollen, pet dander, and mould spores, with both eyes usually affected at once.
• Antihistamine eye drops containing azelastine treat symptoms directly at the eye surface within minutes; oral antihistamines from the broader allergy relief range help when nasal symptoms occur too.
• See a doctor if vision blurs, light sensitivity develops, or symptoms persist beyond a few days.

What sets it off and what it feels like

Dust mites, grass and tree pollen, pet dander, and mould spores are the most frequent triggers. Typical symptoms include intense itching, a gritty or burning sensation, watery discharge, redness, and mild eyelid swelling. It's one of the most common eye complaints, especially in humid climates and dense urban environments where dust mite and mould levels stay elevated year-round. Symptoms often flare alongside other allergic conditions such as hay fever or asthma. Some people have a seasonal pattern that tracks pollen counts, while others react to indoor triggers like dust mites and pet dander all year round.

How it differs from infective conjunctivitis

Allergic conjunctivitis is not contagious, unlike the viral or bacterial forms of conjunctivitis, which often start in one eye before spreading to the other and can produce thicker, coloured discharge. Itching is the dominant symptom in allergic conjunctivitis, whereas grittiness and discharge tend to lead in infective causes. This distinction matters for treatment, since antihistamines do nothing for an infection and antibiotics do nothing for an allergy.

Relieving the itch

Avoiding known triggers is the first step, and cold compresses can soothe irritated eyes quickly. For persistent symptoms, antihistamine eye drops containing azelastine work directly at the eye surface to block the allergic response within minutes. Oral antihistamines from the broader allergy relief range can help when nasal symptoms occur at the same time.

When to see a doctor

See a doctor if vision becomes blurred, light sensitivity develops, or symptoms don't improve after a few days of treatment, since these can signal a more serious eye condition.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.