Allergic conjunctivitis: symptoms, how long it lasts and treatment

It depends on the type and on how long you are exposed to the trigger. Moorfields says that, like hay fever, allergic conjunctivitis can continue for some time (months). It explains that the seasonal type varies with the time of year and the weather, whereas people with more general allergies, for example to dust mites or animals, may have symptoms throughout the year.

NICE CKS describes seasonal allergic conjunctivitis as occurring periodically with seasonal allergens such as tree and grass pollen, and perennial allergic conjunctivitis as linked to non-seasonal allergens often found in the home, such as house dust mites, mould spores or animal dander.

Once treatment is started, Moorfields says anti-allergy eye drops need to be used every day and may take up to two weeks to work. Some people need drops only for a few weeks in the summer, some throughout spring and summer, and others need them all year round.

If you think you have conjunctivitis and your symptoms have not cleared up within 7 days, the NHS advises seeing a GP.

Moorfields lists the treatment options in steps. Avoid rubbing your eyes, because it will make the symptoms worse. A cold compress may help reduce eyelid swelling. Lubricant eye drops or ointment may reduce discomfort but will not stop the allergy process. Anti-allergy eye drops are available over the counter at a chemist, and antihistamine tablets can be taken every day provided there is no medical reason why you cannot use them.

Steroid eye drops are used in severe cases. Moorfields says that if all the above are being used and you still have symptoms, you can ask your GP to request an appointment with your local ophthalmology service, and that steroid drops require a prescription.

NICE CKS describes primary care management as patient information, self-care advice on avoiding allergens and eye rubbing, cold compresses and ocular surface lubricants, consideration of topical antihistamines and/or mast cell stabilisers, with topical diclofenac as adjunctive therapy if required, and follow-up with safety-netting for red flag features.

The NHS says antibiotics will not work if conjunctivitis is caused by an allergy. It also notes that you can hold a cold flannel on your eyes for a few minutes to cool them down.

Moorfields says allergic conjunctivitis usually affects both eyes, with red, itchy, watery eyes, sore eyes, swollen eyelids and sometimes blurry vision caused by the excessive tears. You may also get hay fever symptoms such as sneezing or a runny nose.

The NHS says conjunctivitis with sticky pus is contagious, and eyes that are red and feel gritty are also usually contagious, whereas allergic conjunctivitis makes eyes red and watery without being contagious. NICE CKS lists itching as the most consistent feature of the allergic type.

No. The NHS says conjunctivitis caused by allergies, like hay fever, makes eyes red and watery but is not contagious. Infectious conjunctivitis, by contrast, can spread, and the NHS gives hygiene advice for it, such as washing hands regularly and not sharing towels and pillows. You do not need to stay away from work or school unless you or your child feel very unwell.

CKS groups allergic conjunctivitis into several types, differing in trigger and severity.

The conjunctiva is the thin, clear tissue covering the white of the eye and the inside of the eyelids. NICE Clinical Knowledge Summaries (CKS) defines allergic conjunctivitis as a group of eye conditions linked to an IgE hypersensitivity reaction, meaning the immune system reacts to a normally harmless substance. The NHS describes conjunctivitis generally as an eye condition caused by infection or allergies, also known as red or pink eye.

It often occurs alongside allergic rhinitis, the nasal form of the same allergy. CKS notes that possible associated allergic conjunctivitis, asthma or eczema supports a diagnosis of allergic rhinitis, which is why itchy eyes and a runny nose often come as a pair during the pollen season.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have pain in your eyes, sensitivity to light, changes in your vision such as wavy lines or flashing, very red eyes, or a baby under 30 days old with red, sticky eyes. These can be signs of a more serious eye problem. CKS says serious causes of a red eye, such as acute glaucoma, corneal ulcer, keratitis, iritis, scleritis and trauma, must be excluded, and urgent ophthalmology referral is needed if features such as pain, photophobia, a change in visual acuity or an abnormal pupil are present.

CKS also advises urgent referral if someone wears contact lenses and the cornea may be involved, if they have a systemic disease linked to eye symptoms such as rheumatoid arthritis or Sjogren's syndrome, or if a newborn has a red sticky eye. The NHS adds that contact lens wearers with conjunctivitis symptoms plus spots on the eyelids may be allergic to the lenses and should see a GP.

According to CKS, ophthalmology should be consulted if there is diagnostic uncertainty, appropriate equipment is unavailable, vernal or atopic keratoconjunctivitis is suspected, or the allergic conjunctivitis is severe or resistant to treatment. These types are the ones that can threaten the surface of the eye and need specialist monitoring. The NHS advises seeing a GP if conjunctivitis symptoms have not cleared within 7 days.

The NHS says treatment for a child under 2 years old needs a prescription from a GP, and that a baby under 30 days old with red, sticky eyes needs an urgent GP appointment or NHS 111 help.

Moorfields describes vernal and atopic keratoconjunctivitis, the more severe allergic eye conditions in young people, as similar to eczema but affecting the membrane of the eye. It says they can continue for some time (months to years) but most young people grow out of them, that drops should be used regularly every day and not stopped unless advised, and that it is very important to discourage rubbing or scratching the eyes.

Most people manage allergic conjunctivitis with pharmacy advice and see a GP when symptoms persist. A high-street optometrist can examine the front of the eye and rule out infection or contact lens problems. Moorfields says allergy tests are not helpful, because knowing the trigger does not change the treatment, so be cautious about paying for them. Private ophthalmology review may be useful when the condition is severe or year-round.