What is the appropriate medication for acute conjunctivitis (pink eye)?

Medication for Pink Eye

For bacterial conjunctivitis, prescribe a topical fluoroquinolone such as moxifloxacin 0.5% three times daily for 5–7 days; for viral conjunctivitis, use only supportive care with cold compresses and preservative-free artificial tears; and for allergic conjunctivitis, start with a topical antihistamine/mast cell stabilizer such as olopatadine or ketotifen. 1

Determining the Etiology

The first critical step is distinguishing bacterial, viral, and allergic causes, because treatment differs fundamentally:

• Bacterial conjunctivitis presents with purulent or mucopurulent discharge, mattering and adherence of eyelids on waking, lack of itching, and no history of prior conjunctivitis 2, 3
• Viral conjunctivitis shows watery discharge, follicular reaction on examination, preauricular lymphadenopathy, and is highly contagious 1, 4
• Allergic conjunctivitis is characterized by prominent itching, bilateral involvement, and often concurrent allergic rhinitis or asthma 1, 5

Bacterial Conjunctivitis Treatment

Topical fluoroquinolones are the preferred first-line agents for uncomplicated bacterial conjunctivitis. 1 No single antibiotic has demonstrated superiority, allowing selection based on dosing convenience and cost. 1

Recommended Regimens

• Moxifloxacin 0.5%: Three times daily for 5–7 days, offering superior gram-positive coverage including some MRSA strains, with an 81% complete resolution rate at 48 hours 1
• Alternative options if fluoroquinolones unavailable: Gentamicin, tetracycline, or ofloxacin 0.3% four times daily for 5–7 days 1
• Trimethoprim-polymyxin B: Effective broad-spectrum option, particularly in pediatric populations, with 95% cure or improvement within 7 days 6, 7

Expected Outcomes and Follow-Up

Topical antibiotics provide earlier clinical and microbiological remission (68.2% cure rate versus 55.5% with placebo by days 4–9), allowing faster return to work or school. 1 Instruct patients to return in 3–4 days if no improvement occurs. 1

Special Populations Requiring Different Management

• Contact lens wearers: Reserve fluoroquinolones (ofloxacin or ciprofloxacin) due to higher Pseudomonas risk 1
• Suspected MRSA: Consider compounded topical vancomycin if unresponsive to moxifloxacin within 48–72 hours, as 42% of MRSA isolates show fluoroquinolone resistance 1
• Gonococcal conjunctivitis: Requires systemic ceftriaxone 250 mg IM single dose plus azithromycin 1 g oral single dose, with daily monitoring until resolution 1, 3
• Chlamydial conjunctivitis: Requires systemic azithromycin 1 g oral single dose or doxycycline 100 mg oral twice daily for 7 days, as more than 50% have concurrent infection at other sites 1

Viral Conjunctivitis Treatment

No proven effective treatment exists for adenoviral conjunctivitis; management is supportive care only. 1, 4

Supportive Measures

• Cold compresses to closed eyelids several times daily to reduce inflammation 4
• Preservative-free artificial tears four times daily to dilute viral particles and inflammatory mediators 1, 4
• Topical antihistamines (olopatadine or ketotifen) only if itching is prominent 4

Critical Medications to Avoid

• Do NOT prescribe topical antibiotics: They provide no benefit, add toxicity risk, and promote antimicrobial resistance 1, 4, 2
• Avoid topical corticosteroids in uncomplicated cases: They prolong viral shedding and can exacerbate undiagnosed HSV infection 1, 4, 8

Herpes Simplex Virus (HSV) Conjunctivitis

If HSV is suspected (history of cold sores, vesicular eyelid rash, unilateral disease in atopic patients):

• Topical ganciclovir 0.15% gel three to five times daily OR topical trifluridine 1% solution five to eight times daily 5, 1
• Add oral antivirals: Acyclovir 200–400 mg five times daily, valacyclovir 500 mg two to three times daily, or famciclovir 250 mg twice daily 5, 1
• Never use topical corticosteroids without antiviral coverage, as they potentiate HSV infection 5, 1

Infection Control

Counsel patients that adenoviral conjunctivitis is highly contagious and can survive on surfaces for up to 28 days. 4 Advise:

• Strict hand hygiene with soap and water 1, 4
• Avoid sharing towels, pillows, or personal items 4
• Stay home from school/work for 10–14 days from symptom onset 4

Allergic Conjunctivitis Treatment

Second-generation topical antihistamines with mast cell-stabilizing properties are first-line therapy. 1

Recommended Agents

• Dual-action agents (antihistamine + mast cell stabilizer): Olopatadine (Pataday, Patanol), ketotifen (Alaway, Zaditor), azelastine (Optivar), or epinastine (Elestat) 5, 1
• These have onset of action within 30 minutes and are suitable for acute and longer-term treatment 5

Adjunctive Measures

• Cold compresses 1
• Refrigerated preservative-free artificial tears 1
• Sunglasses as an allergen barrier 1

Second-Line Treatment

If symptoms persist after first-line therapy, add a brief 1–2 week course of low side-effect profile topical corticosteroids (fluorometholone, rimexolone, or loteprednol), with monitoring of intraocular pressure. 1

Medications to Avoid

• Avoid chronic use of topical vasoconstrictors (naphazoline, tetrahydrozoline): They cause rebound vasodilation after prolonged use 5, 1
• Oral antihistamines are less effective than topical agents and may worsen dry eye syndrome 5, 1

Red Flags Requiring Immediate Ophthalmology Referral

Do NOT prescribe medication and arrange urgent ophthalmology evaluation if any of the following are present:

• Visual loss or decreased vision 1, 4
• Moderate to severe eye pain (beyond mild irritation) 1, 4
• Corneal involvement (opacity, infiltrate, or ulcer) 1, 4
• Severe purulent discharge suggesting gonococcal infection 1
• History of HSV eye disease 1, 4
• Immunocompromised state 1, 4
• Conjunctival scarring 1
• Lack of response to therapy after 3–4 days 1

Neonatal Conjunctivitis

Neonatal conjunctivitis requires immediate systemic treatment coordinated with a pediatrician:

• Gonococcal: Ceftriaxone 25–50 mg/kg IV or IM single dose (maximum 125 mg), with daily monitoring until resolution 1, 3
• Chlamydial: Erythromycin base or ethylsuccinate 50 mg/kg/day oral divided into four doses for 14 days 1, 3
• Monitor infants on oral erythromycin for signs of infantile hypertrophic pyloric stenosis 3
• Consider sexual abuse in preadolescent children with gonococcal or chlamydial conjunctivitis 1

Common Pitfalls to Avoid

• Do not use combination antibiotic-steroid drops (e.g., Tobradex) empirically: You must definitively rule out viral conjunctivitis, especially HSV and adenovirus, before using any steroid-containing preparation 1, 8
• Do not prescribe oral antibiotics for routine bacterial conjunctivitis: Topical therapy achieves high tissue concentrations directly at the infection site; oral antibiotics are reserved exclusively for gonococcal and chlamydial conjunctivitis 1
• Do not continue topical trifluridine beyond 2 weeks: It inevitably causes epithelial toxicity with prolonged use 5
• Recognize that mild bacterial conjunctivitis is self-limited: Approximately 64% of cases resolve spontaneously by days 6–10 without treatment 1, 2