What are the appropriate eye drops for treating a patient with conjunctivitis (pink eye)?

Eye Drops for Conjunctivitis (Pink Eye)

The appropriate eye drop depends entirely on the underlying cause—bacterial, viral, or allergic conjunctivitis—and using the wrong treatment can cause harm or delay recovery.

For bacterial conjunctivitis, use topical moxifloxacin 0.5% three times daily for 7 days as first-line treatment, or alternatively gatifloxacin 0.5%, erythromycin ointment, or polymyxin B/trimethoprim if cost is a concern. 1, 2, 3 For allergic conjunctivitis, use second-generation topical antihistamines with mast cell-stabilizing properties (such as olopatadine or ketotifen) as first-line therapy. 4, 1, 2 For viral conjunctivitis, avoid antibiotics entirely and use only supportive care with preservative-free artificial tears and cold compresses. 4, 1, 2

Determining the Etiology

Bacterial Conjunctivitis Features:

• Mucopurulent or purulent discharge with matted eyelids upon waking 1, 5, 6
• Papillary reaction rather than follicular pattern on tarsal conjunctiva 1
• Can be unilateral or bilateral 1
• May have concurrent otitis media, sinusitis, or pharyngitis in children 1
• Absence of itching and no history of prior conjunctivitis episodes 6

Viral Conjunctivitis Features:

• Watery discharge with abrupt onset 1, 5
• Follicular reaction on inferior tarsal conjunctiva 1
• Preauricular lymphadenopathy (especially with adenovirus) 1, 6
• Often starts unilateral but becomes sequentially bilateral 1
• May have concurrent upper respiratory infection 1
• Can present with subconjunctival hemorrhages, chemosis, and eyelid swelling 1

Allergic Conjunctivitis Features:

• Itching is the most consistent and distinguishing feature 4, 1, 6
• Bilateral presentation with watery discharge 1
• May have concurrent allergic rhinitis or asthma 1
• Absence of preauricular lymphadenopathy and matted eyelids 1
• Often seasonal or perennial pattern 4

Treatment by Etiology

Bacterial Conjunctivitis Treatment:

Mild cases are self-limited and may resolve without antibiotics, but topical antibiotics shorten duration and allow earlier return to work/school. 1, 2, 6

First-line options:

• Moxifloxacin 0.5% ophthalmic solution: one drop three times daily for 7 days 3
• Gatifloxacin 0.5%: one drop every 2 hours while awake on day 1 (up to 8 times), then 2-4 times daily on days 2-7 7
• No single antibiotic has proven superiority, so choice can be based on cost and convenience 1, 2

Alternative options if fluoroquinolones unavailable:

• Erythromycin ointment 1, 2
• Polymyxin B/trimethoprim drops 1
• Gentamicin, tetracycline, or ofloxacin 0.3% four times daily for 5-7 days 2

Special circumstances requiring systemic antibiotics:

• Gonococcal conjunctivitis: Ceftriaxone 250 mg IM single dose PLUS azithromycin 1 g oral single dose, with daily follow-up until resolution 1, 2
• Chlamydial conjunctivitis: Azithromycin 1 g oral single dose OR doxycycline 100 mg oral twice daily for 7 days, with evaluation and treatment of sexual partners 1, 2
• Both require systemic therapy because topical treatment alone is inadequate 1, 2

Viral Conjunctivitis Treatment:

Antibiotics provide no benefit and should be avoided entirely. 4, 1, 2

Supportive care only:

• Preservative-free artificial tears four times daily (refrigerated for additional comfort) 4, 1, 2
• Cold compresses for symptomatic relief 4, 1, 2
• Topical antihistamines may provide symptomatic relief for discomfort 4, 1

For severe adenoviral cases with marked chemosis, severe lid swelling, epithelial sloughing, or membranous conjunctivitis:

• Consider short course (1-2 weeks) of low side-effect profile topical corticosteroids (fluorometholone, loteprednol) 4, 1, 2
• Requires close monitoring of intraocular pressure and periodic pupillary dilation for cataract evaluation 4, 1, 2
• Re-evaluate within 1 week 1

For Herpes Simplex Virus (HSV) conjunctivitis:

• Topical ganciclovir 0.15% gel three to five times daily OR trifluridine 1% solution five to eight times daily 1, 2
• Add oral antivirals (acyclovir, valacyclovir, or famciclovir) 1, 2
• Topical corticosteroids are absolutely contraindicated in HSV as they potentiate viral replication and worsen infection 1, 2

Allergic Conjunctivitis Treatment:

First-line therapy:

• Second-generation topical antihistamines with mast cell-stabilizing properties (olopatadine, ketotifen) 4, 1, 2
• Apply as directed, typically twice daily 4, 1

Adjunctive measures:

• Cold compresses 4, 1
• Refrigerated preservative-free artificial tears 4, 1
• Sunglasses as barrier to airborne allergens 4
• Avoid eye rubbing 4

For refractory cases:

• Brief 1-2 week course of low side-effect profile topical corticosteroids 4, 1, 2
• Monitor intraocular pressure if corticosteroids used 4, 1
• Topical cyclosporine or tacrolimus may be helpful in severe cases 4

Avoid chronic use of topical vasoconstrictors as they cause rebound vasodilation 4, 2

Critical Red Flags Requiring Immediate Ophthalmology Referral

• Visual loss or decreased vision 4, 1, 2
• Moderate or severe pain 4, 1, 2
• Severe purulent discharge suggesting gonococcal infection 4, 1, 2
• Corneal involvement (infiltrate, ulcer, opacity) 4, 1, 2
• Conjunctival scarring 4, 1, 2
• History of herpes simplex virus eye disease 4, 1, 2
• Immunocompromised state 4, 1, 2
• Neonatal conjunctivitis (requires systemic treatment and hospitalization) 1, 2
• Recent ocular surgery 1
• Vesicular rash on eyelids or nose 5
• Lack of response to therapy after 3-4 days 1, 2

Common Pitfalls to Avoid

• Never use antibiotics for viral conjunctivitis—they provide no benefit, cause unnecessary toxicity, and contribute to antibiotic resistance 4, 1, 2
• Never use topical corticosteroids in HSV conjunctivitis without antiviral coverage—this potentiates infection and can cause corneal perforation 1, 2
• Never use corticosteroids indiscriminately—they can prolong adenoviral infections, worsen HSV infections, and cause increased intraocular pressure and cataracts 4, 1, 2
• Do not miss gonococcal conjunctivitis—it requires immediate systemic treatment as it can cause corneal perforation 1, 2
• Do not use oral antibiotics for routine bacterial conjunctivitis—topical therapy achieves much higher tissue concentrations and oral antibiotics are reserved exclusively for gonococcal and chlamydial infections 2
• Avoid contact lens wear during any form of infectious conjunctivitis 1
• Consider sexual abuse in children with gonococcal or chlamydial conjunctivitis 1, 2

Infection Control

• Strict hand hygiene with soap and water 4, 1, 2
• Avoid sharing towels, pillows, or personal items 4
• Minimize contact with others for 10-14 days from symptom onset in viral conjunctivitis 1
• Discard multiple-dose eyedrop containers after infection resolves to avoid reinfection 2