How can I tell whether my conjunctivitis is allergic, viral or bacterial?

Conjunctivitis symptoms tend to vary according to the cause. If it isn’t clear whether the inflammation is triggered by an infection, allergy or irritation, customers frequently see their pharmacist. “Bacterial conjunctivitis usually causes a sticky discharge and crusting of the eyelids, which can often be stuck together on waking,” says Poonam Patel, RNIB’s eye health information officer.

“It usually affects both eyes, but one eye may be affected before the other.” Viral conjunctivitis usually causes lots of watery discharge and irritation, she says.

“It often starts in one eye but spreads quite quickly to the other eye. If it is allergic conjunctivitis, your customer may experience intense itching and tearing of the eyes, as well as sneezing and watery nasal discharge. Both eyes are usually affected at the same time.”

Most customers with infective conjunctivitis can use OTC chloramphenicol eye drops as a first-line option. If the infection is particularly severe or lasts for more than two weeks, customers should see their GP. Allergic conjunctivitis usually clears up with the use of sodium cromoglicate eye drops, for example.