In what scenarios should I consider prescribing topical antibiotics for a patient with red eye?

Topical antibiotics should be considered for a patient presenting with a red eye primarily in cases of acute bacterial conjunctivitis when symptoms are severe or when rapid resolution is clinically required. Most bacterial conjunctivitis cases are self-limiting and resolve within 5–7 days without treatment, so antibiotics are not routinely prescribed unless special circumstances apply. A delayed prescribing strategy, advising patients to start antibiotics if symptoms persist beyond 3 days, is recommended to reduce unnecessary antibiotic use.

In patients who wear soft contact lenses presenting with conjunctivitis, topical antibiotics effective against Gram-negative organisms (e.g., aminoglycosides like gentamicin or quinolones such as levofloxacin or moxifloxacin) should be considered due to the higher risk of serious infection. Contact lens use should be stopped immediately, and referral to ophthalmology is advised if corneal involvement is suspected.

Topical antibiotics are not appropriate for viral (non-herpetic) conjunctivitis, as this condition is self-limiting and antibiotics do not improve outcomes but may cause adverse effects and promote resistance. Instead, supportive care with lubricants and hygiene measures is recommended.

Referral to ophthalmology should be considered if symptoms persist beyond 7 to 10 days despite treatment or if there is suspicion of sight-threatening complications such as corneal involvement or conjunctival pseudomembrane.