Allergic Conjunctivitis: Symptoms, Triggers and Treatment

Allergic conjunctivitis is an eye reaction to allergens that can cause itching, redness, watering and eyelid swelling.

The conjunctiva is the thin clear tissue over the white of the eye and inside the eyelids. When it reacts to an allergen, the eye releases chemicals that make blood vessels more visible and stimulate itch-sensitive nerves. It may affect one eye before the other, but both eyes are often involved.

Itching and red eyes are very common presentations of allergic conjunctivitis. Watery eyes, a gritty feeling, puffy lids and stringy or clear discharge can also occur. Rubbing may briefly feel relieving but can increase irritation and swelling.

Thick yellow or green discharge, marked pain, light sensitivity, a change in vision, or difficulty opening the eye needs prompt clinical assessment because these features can have causes other than allergy.

Pollen, house dust mites, animal dander, mould and airborne irritants can trigger symptoms in people with a sensitised immune system. The trigger may reach the eyes outdoors, be carried indoors on clothing, or be disturbed during cleaning. Fragrances and smoke can irritate the eyes even when they are not the underlying allergy trigger.

Symptoms often fluctuate with exposure. Some people notice a seasonal pattern, while others have episodes around pets, dusty rooms or particular work environments. Symptoms can settle when exposure reduces and return after renewed contact. Ongoing rubbing may leave the eyelid skin sore or make the surface of the eye feel more inflamed.

A personal or family tendency toward allergic conditions can make allergic conjunctivitis more likely. People who also have nasal allergies may notice eye symptoms during the same exposure. Contact lenses can feel less comfortable when the eye surface is irritated, and dust or pollen trapped on lenses may add to discomfort.

A clinician will ask about timing, triggers, other allergy symptoms, contact lens use and medicines. They examine the eyelids and eye surface and may check vision. Testing is not needed for every episode, but it can help identify a suspected allergen when symptoms recur, are difficult to control, or the trigger remains unclear.

Reducing contact with a known trigger is a useful starting point. Cool compresses and preservative-free lubricating drops may soothe irritation. A pharmacist or clinician may recommend allergy eye drops or other allergy medicine, depending on your symptoms, health conditions and medicines already in use. Do not use leftover prescription eye drops without advice.

Keeping a short note of where symptoms occur can reveal a pattern. Showering or washing the face after time outdoors, keeping windows closed during a known trigger period, and changing pillowcases regularly may reduce exposure for some people. Avoid sharing eye cosmetics and replace products that have touched an irritated eye.

Use wraparound glasses outdoors when wind carries dust or pollen, and clean surfaces with a damp cloth rather than stirring dust into the air. If symptoms reliably follow a particular exposure, discussing a prevention plan before that exposure may help you prepare.

See a GP, optometrist or eye specialist for persistent or recurrent symptoms, uncertainty about the cause, or problems using contact lenses. Seek urgent care for severe eye pain, injury, sudden vision change, marked light sensitivity, or a painful red eye.