Bacterial conjunctivitis is much less common than viral or allergic conjunctivitis in adults. Children and people with chronic ocular conditions tend to be more prone to bacterial conjunctivitis.

Patients will typically complain of ocular irritation, redness, foreign body sensation, and tearing associated with increased discharge. Itching is less common in bacterial conjunctivitis.

Inoculation of the conjunctiva is usually by direct hand-eye contact or can be due to direct spread of organisms located in the patient's own nasal passageway or sinuses. Often, patients will have concurrent sinus disease, upper respiratory infection (URI), or infectious dacryocystitis (infection of the lacrimal sac).

The onset of symptoms is usually over days to weeks but can be as short as 24 hours (hyperacute) or as long as years (chronic conjunctivitis). Hyperacute conjunctivitis is typically caused by Neisseria gonorrhoeae, and chronic conjunctivitis is typically caused by Chlamydia trachomatis or Staphylococcus associated with blepharitis. Acute forms of bacterial conjunctivitis are the most common manifestations associated with the diagnosis.

Note: As of November 15, 2023, the US Food and Drug Administration (FDA) is reminding the public not to purchase or use certain eyedrops from several major brands due to risk of eye infection. Refer to the FDA list for more information. As of January 31, 2024, the FDA is warning consumers not to purchase or use South Moon, Rebright, or FivFivGo eye drops because of the potential risk of eye infection; these are copycat products easily mistaken for Bausch + Lomb's Lumify brand eye drops.