Polymyxin B/Trimethoprim Shortage: What Providers and Prescribers Need to Know in 2026

This briefing is intended for ophthalmologists, optometrists, primary care physicians, pediatricians, urgent care providers, and other clinicians who regularly prescribe Polymyxin B/Trimethoprim (Polytrim) for bacterial conjunctivitis and blepharoconjunctivitis. It covers the current supply situation, recommended therapeutic alternatives, and practical guidance for managing affected patients.

Current Supply Status (2026)

The Polymyxin B/Trimethoprim shortage, documented by ASHP beginning March 2023, has substantially resolved at the national level. Bausch Health and Sandoz both have polymyxin B sulfate/trimethoprim sulfate ophthalmic solution 10,000 units/mL–1 mg/mL available through their respective distribution channels as of the ASHP update in November 2024.

However, pharmacy-level availability remains inconsistent. Your patients may still encounter stock-outs at their preferred pharmacy, particularly at chain pharmacies that source through centralized wholesalers. Independent pharmacies and those with diversified supplier relationships are more likely to have the product in stock. Prescribers should anticipate continued patient calls about difficulty filling this prescription.

Root Cause: Akorn's Market Exit

The primary driver of the shortage was the February 2023 closure of Akorn, Inc. Akorn was one of the largest U.S. manufacturers of generic ophthalmic solutions, and their exit removed substantial supply of multiple ophthalmic medications simultaneously. Greenstone (Viatris) also discontinued their polymyxin B/trimethoprim formulation around the same period. The market concentration among generic ophthalmic manufacturers meant that Akorn's failure had disproportionate downstream impact.

Clinical Context: When Is Polymyxin B/Trimethoprim Appropriate?

Polymyxin B/Trimethoprim remains a first-line recommendation for mild to moderate acute bacterial conjunctivitis and blepharoconjunctivitis in patients aged 2 months and older. It provides broad-spectrum coverage:

Trimethoprim component: Covers gram-positive organisms including S. aureus, S. epidermidis, S. pneumoniae, and viridans streptococci via dihydrofolate reductase inhibition.

Polymyxin B component: Covers gram-negative organisms including Pseudomonas aeruginosa, E. coli, K. pneumoniae, Enterobacter aerogenes, and H. influenzae via cell membrane disruption.

A published randomized controlled trial (PubMed, 2012) comparing Polymyxin B/Trimethoprim to moxifloxacin in pediatric acute conjunctivitis found clinical cure rates of 96% and 95%, respectively — not statistically different. This supports continued use of Polytrim as a cost-effective first-line option when available.

Recommended Therapeutic Alternatives

When Polymyxin B/Trimethoprim is unavailable, consider the following alternatives based on clinical presentation:

Moxifloxacin 0.5% (Vigamox, Moxeza): Preferred alternative for moderate infections or when faster resolution is clinically important. Dosing: 1 drop TID for 7 days (Vigamox) or BID for 7 days (Moxeza). Broad spectrum; reserve for appropriate clinical scenarios to preserve antimicrobial stewardship.

Ciprofloxacin 0.3% (Ciloxan): Fluoroquinolone; also approved for corneal ulcers. Appropriate when corneal involvement is suspected. Dosing: 1–2 drops q2h while awake for 2 days, then q4h for 5 days.

Ofloxacin 0.3% (Ocuflox): Similar fluoroquinolone option with good gram-negative coverage. Approved for ages ≥1 year. Dosing: 1–2 drops q2–4h while awake for 2 days, then q4h for 5 days.

Tobramycin 0.3% (Tobrex): Aminoglycoside; preferred when Pseudomonas is suspected (contact lens wearers). Dosing: 1–2 drops q4h for mild/moderate infections.

Erythromycin 0.5% ophthalmic ointment: Macrolide; appropriate for neonates and mild gram-positive infections. Limited gram-negative coverage.

Prescribing Tips to Improve Patient Access

When prescribing Polymyxin B/Trimethoprim, note on the Rx that either the Bausch or Sandoz generic is acceptable — this gives pharmacists more flexibility in sourcing.

Consider providing a backup alternative prescription or communicating to your staff that a switch to ciprofloxacin or moxifloxacin can be authorized by message if the patient cannot fill within 24 hours.

Advise patients to call pharmacies proactively before making a trip, or to use a pharmacy search service to check stock across multiple locations simultaneously.

Update your EHR order sets to flag that Polytrim may not be in stock and offer preferred alternatives at the time of prescribing.

Antimicrobial Stewardship Considerations

While fluoroquinolone alternatives are clinically effective, they carry greater risk of selecting for fluoroquinolone-resistant organisms if used too broadly. Resistance rates for Pseudomonas aeruginosa to moxifloxacin have been increasing in some regions. When Polymyxin B/Trimethoprim is available and appropriate, it remains the preferred first-line choice for mild bacterial conjunctivitis due to its low resistance profile (approximately 3% Pseudomonas resistance to polymyxin B, and 3–7% S. aureus resistance to trimethoprim) and established safety record.

Patient Communication Guidance

Many patients are unaware that supply issues at their pharmacy don't mean the medication doesn't exist. Encourage patients to try multiple pharmacies, use a pharmacy-finding service, or ask your office for an alternative prescription if they can't fill within 24 hours. Directing patients to pharmacy-finding resources like medfinder can reduce the volume of callbacks your office receives about prescription fulfillment.

Summary

The Polymyxin B/Trimethoprim shortage has largely resolved at the manufacturer level, but pharmacy stock remains uneven. The drug is not discontinued and remains clinically appropriate for mild to moderate bacterial conjunctivitis. Having a ready alternative and a patient-facing pharmacy search strategy in place will minimize patient delays. For more detailed guidance, see our provider guide to helping patients find Polymyxin B/Trimethoprim.