Conjunctivitis - including symptoms, treatment and prevention

Conjunctivitis, sometimes known as ‘sticky eye’, is an inflammation of the lining of the eye and eyelid caused by bacteria, viruses, chemicals or allergies.

How conjunctivitis is spread

Viral and bacterial conjunctivitis can be spread by direct contact with eye secretions or indirectly by contact with towels, washcloths, handkerchiefs and other objects that have been contaminated with eye secretions. In some cases it can be spread by insects such as flies. Conjunctivitis caused by chemicals or allergies is not infectious.

Signs and symptoms

a partially open eye showing conjunctivitisSymptoms may include:

  • redness in the whites of the eyes
  • irritation in one or both eyes
  • discharge, causing the eyelids to stick together in the morning (see image)
  • swelling of the eyelids (see image)
  • sensitivity to light.


Diagnosis is made by clinical and/or microscopic examination and culture of discharge from the eye. It is usually not possible to tell whether the conjunctivitis is caused by bacteria or viruses without laboratory tests.

Incubation period

(time between becoming infected and developing symptoms)

Usually 24 to 72 hours.

Infectious period

(time during which an infected person can infect others)

While the eye discharge is present.


Antibiotic eye drops or ointment may be prescribed by a doctor.

Since bacterial and viral infections look the same, a person with symptoms of conjunctivitis should always be seen by a doctor for examination, diagnosis and treatment.


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