Conjunctivitis is an inflammation of the conjunctiva that is sometimes accompanied by corneal inflammation (keratoconjunctivitis). The etiology of conjunctivitis can be infectious or noninfectious (e.g., allergic conjunctivitis). Common clinical findings include itching, burning, and ocular discharge; the clinical presentation sometimes suggests the underlying etiology (e.g., infections may manifest with purulent discharge, while keratoconjunctivitis sicca is characterized by dry eye). Conjunctivitis is the most common cause of ocular hyperemia but differential diagnoses include keratitis, acute glaucoma, and subconjunctival hemorrhages. Treatment depends upon the underlying cause; viral conjunctivitis is usually self-limited and requires only supportive therapy for conjunctivitis, whereas most types of bacterial conjunctivitis require antibiotics. Treatment of noninfectious conjunctivitis may include behavior changes (e.g., reducing contact lens use), topical treatment, or systemic treatments. If symptoms are severe or recurrent, or complex etiologies are suspected (e.g., autoimmune conditions), patients should be referred to an ophthalmologist early for specialized management. Surgical intervention is rarely necessary.
For more comprehensive information on the diagnosis and management of conjunctivitis subtypes, see “Bacterial conjunctivitis,” “Viral conjunctivitis,” and “Noninfectious conjunctivitis.” For management in newborns, see “Neonatal conjunctivitis.”
|Overview of conjunctivitis subtypes in children and adults |
|Bacterial conjunctivitis|| |
Allergic conjunctivitis 
|Acute bacterial conjunctivitis||Gonococcal conjunctivitis ||Trachoma|
|Clinical features|| || |
- Typically nonspecific presentation; common clinical features include: 
- Burning or foreign body sensation
- Itching (most intense in seasonal allergic conjunctivitis)
- Conjunctival injection: conjunctival hyperemia with dilatation of blood vessels → ocular hyperemia and red eye
- Chemosis: edema of the conjunctiva due to conjunctival vein vasodilatation and increased blood flow
- Discharge and crust formation
- Additional features may be present depending on etiology, including:
- Conjunctival follicle: seen in viral or chlamydial conjunctivitis
- Preauricular lymphadenopathy: seen in viral or gonococcal conjunctivitis
- Concomitant corneal inflammation (keratoconjunctivitis): seen in viral and nonallergic conjunctivitis
- Moderate to severe eye pain
- Photophobia, blurriness, or vision loss
- Conjunctival scarring
- Grossly visible corneal changes (e.g., corneal ulcer)
- Hyperacute bacterial conjunctivitis
- Vesicular rash
Red flags in conjunctivitis indicate severe etiologies that require specialized management.
Conjunctivitis is usually a clinical diagnosis. Consider diagnostic studies if there is diagnostic uncertainty or suspicion for a serious infection. 
- Obtain a full medical history including comorbidities, medications, and history of eye conditions.
- Perform eye examination, including: 
- Routine studies: conjunctival swabs for infectious etiologies (e.g., smear, culture, PCR) 
- Additional studies to consider: 
- Provide supportive therapy to all patients.
- Start specific treatment if needed based on the suspected cause; see:
- Refer to ophthalmology if there are:
Patient education is vital to prevent conjunctivitis outbreaks.
Supportive therapy for conjunctivitis 
- Apply refrigerated artificial tears as often as needed.
- Eyelid hygiene e.g.,
- Compresses (can be warm or cold)
- Advise patients to stop using contact lenses for ≥ 2 weeks. 
- Educate patients on the prevention of conjunctivitis.
Prevention of infectious conjunctivitis 
- Educate patients on general preventive measures.
- Avoid touching the eyes.
- For contact lens users, ensure patients maintain contact lens hygiene. 
- Wash hands before inserting and removing lenses.
- Clean lenses with specially designed disinfection solutions, not tap water.
- Adhere to replacement schedules for contact lenses and storage cases.
- Avoid sleeping with lenses in.
- Avoid exposing contact lenses to water while showering or swimming.
- Replace the solution in storage cases instead of topping it up.
- Encourage routine vaccinations (see “Immunization schedule”).
- To prevent onward transmission, advise patients with active infections to:
- Isolate at home if possible. 
- Disinfect hands and surfaces frequently.
- Avoid sharing items (e.g., towels, cosmetics).
- Remove contact lenses, discard disposable lenses, and avoid wearing lenses again for ≥ 2 weeks.