Treatment of Pink Eye (Conjunctivitis)
Determine the Etiology First
The most critical step is distinguishing between viral, bacterial, and allergic conjunctivitis, as treatment differs fundamentally for each type. 1, 2
Key Clinical Features to Guide Diagnosis:
Bacterial conjunctivitis:
- Mucopurulent discharge with eyelids matted shut upon waking 3, 4
- Lack of itching 4
- More common in children 3
- Unilateral or bilateral presentation 1
Viral conjunctivitis:
- Watery discharge 3, 4
- Follicular reaction on conjunctiva 5
- Preauricular lymphadenopathy 5
- More common in adults 3
- Often preceded by upper respiratory infection 1
Allergic conjunctivitis:
- Itching is the hallmark symptom 4, 6
- Bilateral presentation 5
- Mucoid discharge, chemosis, eyelid edema 6
- History of atopy or concurrent allergic rhinitis 1
Treatment by Etiology
Bacterial Conjunctivitis
For mild bacterial conjunctivitis in immunocompetent adults, observation without antibiotics is a valid first-line approach, as the condition is typically self-limited with 64% resolving spontaneously by days 6-10. 2, 1 However, topical antibiotics shorten symptom duration by 2-5 days and allow earlier return to work or school. 1, 2
First-Line Topical Antibiotic Therapy:
Prescribe a 5-7 day course of broad-spectrum topical antibiotics if treatment is desired. 1, 2
Preferred agents:
- Fourth-generation fluoroquinolones (moxifloxacin 0.5% or gatifloxacin) three to four times daily provide superior gram-positive coverage, including activity against some MRSA strains 1, 5
- Alternative options: ofloxacin 0.3%, gentamicin, or tetracycline four times daily if fluoroquinolones are unavailable or cost-prohibitive 1, 5
- No single antibiotic shows superiority for uncomplicated cases, so choose based on convenience and cost 1, 2
For contact lens wearers: Reserve fluoroquinolones due to higher risk of Pseudomonas infection 1, 5
Moderate to Severe Bacterial Conjunctivitis:
Obtain conjunctival cultures and Gram staining before initiating treatment, especially if gonococcal infection is suspected. 7, 1 Start empiric broad-spectrum topical fluoroquinolones while awaiting culture results. 1
Consider MRSA coverage in nursing home residents or patients with community-acquired infections, as MRSA isolates are generally resistant to fluoroquinolones and aminoglycosides but susceptible to vancomycin. 7, 1 Compounded topical vancomycin may be required if unresponsive to fluoroquinolones within 48-72 hours. 1, 5
Special Circumstances Requiring Systemic Antibiotics:
Gonococcal conjunctivitis:
- Systemic antibiotic therapy is mandatory in addition to topical treatment 7, 1, 2
- Adults: Ceftriaxone 1 g IM single dose plus azithromycin 1 g orally single dose 1
- Add saline lavage for comfort 7
- Daily monitoring until resolution is required to prevent corneal perforation 7, 1
- Evaluate for concurrent urethritis, cervicitis, or pelvic inflammatory disease 2
Chlamydial conjunctivitis:
- Systemic therapy is required, as >50% of infants have concurrent infection at other sites (nasopharynx, genital tract, lungs) 7, 1
- Adults: Azithromycin 1 g orally single dose or doxycycline 100 mg orally twice daily for 7 days 1, 5
- Infants: Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into 4 doses for 14 days 1, 5
- No evidence supports adding topical therapy to systemic treatment 7, 1
- Re-evaluate after treatment completion, as failure rates can reach 19% 7, 1
- Consider sexual abuse in children with gonococcal or chlamydial conjunctivitis 7, 1
Viral Conjunctivitis
Viral conjunctivitis requires supportive care only, as no proven effective treatment exists for adenovirus (the most common cause). 5, 6
Supportive measures:
- Refrigerated preservative-free artificial tears four times daily 5, 3
- Cold compresses for comfort 5, 3
- Topical antihistamines for symptomatic relief of itching 5
- Strict hand hygiene with soap and water to prevent transmission 7, 1
- Avoid close contact for 7-14 days from symptom onset 5
Avoid topical antibiotics, as they provide no benefit and risk adverse effects and antimicrobial resistance. 7, 5
Herpes Simplex Virus (HSV) Conjunctivitis:
Topical antivirals are required:
- Ganciclovir 0.15% gel three to five times daily OR trifluridine 1% solution five to eight times daily 5
- Add oral antivirals (acyclovir, valacyclovir, or famciclovir) 5
- Never use topical corticosteroids in HSV conjunctivitis without antiviral coverage, as steroids potentiate viral replication and worsen infection 5, 8
Severe Adenoviral Conjunctivitis:
Topical corticosteroids may be considered only in severe cases with marked chemosis, severe lid swelling, epithelial sloughing, or membranous conjunctivitis, but require close monitoring for elevated intraocular pressure and cataract formation. 5, 8 Use low side-effect profile steroids (fluorometholone, rimexolone, or loteprednol) at minimum effective dose with slow taper. 5
Allergic Conjunctivitis
Second-generation topical antihistamines with mast cell-stabilizing properties are first-line therapy for allergic conjunctivitis. 5, 4
Treatment algorithm:
- First-line: Topical antihistamine/mast cell stabilizers (e.g., olopatadine, ketotifen) 5, 4
- Adjunctive measures: Cold compresses, refrigerated preservative-free artificial tears, sunglasses as allergen barrier 5
- Second-line: Brief 1-2 week course of low side-effect profile topical corticosteroids if symptoms persist, with monitoring of intraocular pressure 5
Avoid chronic use of topical vasoconstrictors, as they cause rebound vasodilation. 5 Oral antihistamines may worsen dry eye syndrome and exacerbate allergic conjunctivitis. 5
Red Flags Requiring Immediate Ophthalmology Referral
Refer urgently if any of the following are present: 7, 1, 2
- Visual loss or decreased vision
- Moderate to severe pain (beyond mild irritation)
- Severe purulent discharge
- Corneal involvement (opacity, infiltrate, or ulcer)
- Conjunctival scarring or membrane formation
- Lack of response to appropriate therapy after 3-4 days
- Recurrent episodes
- History of HSV eye disease
- Immunocompromised state
- Neonatal conjunctivitis (requires systemic treatment)
Follow-Up Strategy
For routine bacterial conjunctivitis: Advise patients to return in 3-4 days if no improvement is noted. 7, 1 At follow-up, perform interval history, visual acuity measurement, and slit-lamp biomicroscopy. 7, 1
For gonococcal conjunctivitis: Daily visits until resolution are mandatory. 7, 1
For chlamydial conjunctivitis: Re-evaluate after treatment completion due to potential 19% failure rate. 7, 1
Patients may return to work or school after 24-48 hours of antibiotic treatment if symptoms are improving. 2 Complete resolution typically occurs within 7-10 days with appropriate treatment. 2
Critical Pitfalls to Avoid
- Do not prescribe systemic antibiotics for uncomplicated bacterial conjunctivitis—topical therapy achieves high tissue concentrations directly at the infection site 1
- Do not use topical corticosteroids without ruling out HSV, as steroids potentiate HSV infection and can cause corneal perforation 5, 8
- Do not use antibiotics for viral conjunctivitis, as they provide no benefit and promote resistance 7, 5
- Do not use combination antibiotic-steroid drops (e.g., Tobradex) in pediatric conjunctivitis unless viral etiology has been definitively excluded 1
- Instruct patients to avoid contact lens wear during active conjunctivitis 2
- Do not taper antibiotic doses below 3-4 times daily, as subtherapeutic doses increase resistance risk 1
Alternative When Antibiotics Are Unavailable
Povidone-iodine 1.25% ophthalmic solution may be equally effective as topical antibiotics for bacterial conjunctivitis in settings with limited antibiotic access. 7, 1, 2