What is the appropriate treatment for pink eye (acute conjunctivitis) based on the likely cause?

Treatment of Pink Eye (Acute Conjunctivitis)

The appropriate treatment for pink eye depends entirely on the underlying cause: viral conjunctivitis requires only supportive care with artificial tears and cold compresses, bacterial conjunctivitis may benefit from topical antibiotics (especially moderate-to-severe cases), and allergic conjunctivitis responds best to topical antihistamines with mast cell-stabilizing activity. 1

Determine the Etiology First

Viral Conjunctivitis (Most Common in Adults)

• Watery discharge with a follicular reaction on the inferior tarsal conjunctiva strongly suggests viral etiology 1, 2
• Preauricular lymphadenopathy, concurrent upper respiratory infection, or contact with someone who has red eye point toward viral cause 1, 3
• Abrupt onset, often starting unilateral but becoming sequentially bilateral within days 1, 2
• Self-limited course resolving within 5-14 days 1

Bacterial Conjunctivitis (More Common in Children)

• Mucopurulent or purulent discharge with matted eyelids upon waking indicates bacterial infection 1, 3
• Papillary (not follicular) conjunctival reaction 1, 2
• May be associated with concurrent otitis media, sinusitis, or pharyngitis in children 1, 3
• Absence of itching helps distinguish from allergic causes 1

Allergic Conjunctivitis

• Itching is the hallmark symptom and most consistent distinguishing feature 1, 4
• Bilateral presentation with watery discharge and mild mucous component 1, 2
• History of atopy, asthma, or eczema supports this diagnosis 1
• Seasonal or perennial pattern depending on allergen exposure 1

Treatment by Etiology

Viral Conjunctivitis: Supportive Care Only

• Do NOT prescribe topical antibiotics—they provide no benefit and may cause unnecessary toxicity 1, 5
• Prescribe preservative-free artificial tears for symptomatic relief 1
• Recommend cold compresses to reduce conjunctival swelling 1
• Topical antihistamines (e.g., olopatadine) may provide symptomatic relief of itching and redness 1
• Patient education is critical: highly contagious for 10-14 days from symptom onset 1
  • Strict hand hygiene with soap and water 1
  • Avoid sharing towels, pillows, or linens 1
  • Avoid rubbing eyes 1
  • Virus can survive on dry surfaces for up to 28 days 1

Bacterial Conjunctivitis: Selective Antibiotic Use

• Mild cases are usually self-limited and may resolve without treatment, but topical antibiotics can shorten duration 1, 4
• For moderate-to-severe cases: prescribe a 5-7 day course of broad-spectrum topical antibiotic 1
• No single antibiotic is superior—choose the most convenient or cost-effective option 1:
  • Erythromycin ointment
  • Polymyxin B/trimethoprim drops
  • Fluoroquinolones (remain effective despite increasing MRSA prevalence) 1
• Delayed antibiotic prescribing has similar symptom control as immediate prescribing 5

Allergic Conjunctivitis: Antihistamines First-Line

• Topical antihistamines with mast cell-stabilizing activity (olopatadine or ketotifen) are first-line treatment 1, 5
• Environmental modifications 1:
  • Wear sunglasses as a barrier to airborne allergens
  • Use cold compresses and refrigerated artificial tears
  • Avoid known allergens
• Oral antihistamines are less effective than topical agents for ocular symptoms 1
• For refractory cases, consider a brief 1-2 week course of topical corticosteroids with low side-effect profile 1

Special Situations Requiring Systemic Therapy

Gonococcal Conjunctivitis (Vision-Threatening Emergency)

• Immediate systemic therapy required: single IM dose of ceftriaxone 250 mg PLUS single oral dose of azithromycin 1 g 1
• Hospitalization necessary for parenteral therapy 1
• Daily ophthalmology follow-up until resolution 1
• Can cause corneal perforation within 24 hours if untreated 1
• Treat sexual contacts 1

Chlamydial Conjunctivitis

• Systemic antibiotics required—topical therapy alone is inadequate 1, 4
• Evaluate and treat sexual partners 1
• Re-evaluate after treatment completion 1

Red Flags Requiring Urgent Ophthalmology Referral

Refer immediately (within 24 hours) for any of the following 1, 5:

• Visual loss or decreased vision
• Moderate or severe pain (beyond mild irritation)
• Corneal involvement (opacity, infiltrate, ulceration)
• Conjunctival scarring or pseudomembrane formation
• Severe purulent discharge
• History of herpes simplex virus eye disease
• Recent ocular surgery or trauma
• Contact lens wear (risk of bacterial keratitis)
• Immunocompromised state
• Lack of improvement after 5-7 days of appropriate therapy

Critical Pitfalls to Avoid

• Never use topical corticosteroids indiscriminately—they prolong adenoviral infections, worsen HSV infections, and increase intraocular pressure and cataract risk 1
• Avoid prescribing antibiotics for viral conjunctivitis—this contributes to antimicrobial resistance and exposes patients to unnecessary adverse effects 1, 6
• Do not miss gonococcal conjunctivitis—failure to recognize this can lead to corneal perforation and permanent vision loss 1
• Contact lens wear must be discontinued during any infectious conjunctivitis 1
• Chronic use of topical vasoconstrictors causes rebound vasodilation 1
• If topical corticosteroids are used (severe viral cases only), baseline and periodic IOP measurement and pupillary dilation are mandatory 7, 1

Follow-Up Recommendations

• Patients with severe viral conjunctivitis should return within 1 week 1
• Those not on corticosteroids should return if symptoms persist beyond 2-3 weeks 1
• Bacterial conjunctivitis should improve within 5-7 days; if not, obtain cultures and susceptibility testing 1