Conjunctivitis: symptoms, causes and treatment

Conjunctivitis is inflammation of the thin membrane covering the eye and inner eyelid, often causing redness, irritation and discharge.

It may affect one eye before spreading to the other, or affect both from the start. Viral, bacterial and allergic forms can feel similar at first, but their triggers and management differ. A red, sticky or uncomfortable eye can also have causes other than conjunctivitis, so changes in vision or marked pain need prompt assessment.

Redness, a gritty feeling, watering and eyelids that stick together after sleep are typical. Eye discharge is a very common presentation of conjunctivitis; it may be watery or more sticky. Light sensitivity can occur, although pronounced sensitivity, severe pain or reduced vision should be assessed urgently rather than assumed to be simple conjunctivitis.

Viruses can trigger conjunctivitis during a cold-like illness and may spread through hands, shared towels or close contact. Bacteria can also infect the surface of the eye. Allergic conjunctivitis is linked to an immune reaction to triggers such as pollen, dust or animal dander and often brings itching in both eyes. Irritants, including smoke, cosmetics or chlorinated water, can inflame the conjunctiva without an infection.

Symptoms may build over a short period and can fluctuate during the day. Infectious conjunctivitis often begins with irritation and watering, followed by redness and discharge. Allergic symptoms can return when the trigger is present. Avoid wearing contact lenses until the eye is comfortable and a clinician has advised when they can be used again, particularly if there is discharge or pain.

Close contact with someone who has an infectious eye condition, touching the eyes after handling contaminated items, and sharing face cloths or eye makeup can increase the chance of acquiring an infection. Seasonal allergies, a history of eczema or asthma, and regular exposure to airborne irritants can make allergic or irritant symptoms more likely. Contact lens wear needs particular care because a painful red eye in a lens wearer needs timely clinical review.

A clinician will ask when the symptoms started, whether one or both eyes are involved, the type of discharge, recent illness, allergies and contact lens use. They examine the eye and eyelids, and may check vision. Further tests are not needed in many straightforward cases, but a swab or specialist examination may be considered when symptoms are severe, recurrent or do not settle as expected.

Gentle cleaning of crusting with clean water, handwashing and avoiding eye rubbing can improve comfort and reduce spread. Cool compresses may soothe itching or irritation. Treatment depends on the suspected cause: allergy treatment may be considered for an allergic pattern, while antibiotic treatment may be used when a clinician suspects a bacterial infection. Antibiotics do not treat viral conjunctivitis.

Use a separate clean towel and pillowcase where practical, wash hands before and after touching the face, and avoid sharing eye drops or cosmetics. Discard eye makeup used while symptoms were active. If work, school or childcare attendance is a concern, a GP can advise based on the likely cause, the severity of symptoms and local requirements.

Seek urgent medical assessment for severe eye pain, a significant change in vision, marked light sensitivity, swelling around the eye, injury, or a red painful eye while wearing contact lenses. These features may point to involvement beyond the conjunctiva and should not be managed with home care alone.

Hand hygiene is central to reducing transmission of infectious forms. Do not share towels, washcloths, eye products or contact lens equipment. For recurring allergy symptoms, identify likely triggers and limit exposure where feasible; rinse away irritants promptly and use protective eyewear for dusty tasks.

A GP can assess a red or irritated eye, review medicines and allergies, and advise whether treatment or an eye specialist referral is needed. Arrange an appointment sooner if symptoms are worsening, recurring, linked to contact lenses, or affecting normal activities.