Colistin Shortage: What Providers and Prescribers Need to Know in 2026

Provider Briefing: Colistin Shortage in 2026

Colistimethate Sodium — the prodrug form of Colistin (Polymyxin E) — remains one of the most critically needed yet inconsistently available antibiotics in the U.S. formulary. As multidrug-resistant (MDR) gram-negative infections continue to rise, the gap between clinical need and pharmaceutical supply has become a persistent challenge for prescribers.

This briefing provides infectious disease physicians, intensivists, pulmonologists, and hospital pharmacists with an up-to-date overview of the Colistin shortage, its clinical implications, and actionable strategies for patient management.

Shortage Timeline

Colistimethate Sodium has been on and off the ASHP Current Drug Shortages list since approximately 2015. Key milestones include:

• 2015-2018: Initial supply constraints as demand increased due to rising carbapenem-resistant organism (CRO) rates. Par Pharmaceutical (Endo International) experienced manufacturing disruptions.
• 2019-2021: Xellia Pharmaceuticals received FDA approval for a generic Colistimethate Sodium formulation, providing an additional supply source. However, global demand continued to outpace production capacity.
• 2022-2024: Intermittent shortages persisted. The overall U.S. drug shortage environment hit record levels — 323 active shortages in Q1 2024 per ASHP — placing additional strain on anti-infective supply chains.
• 2025-2026: Supply remains constrained. While the number of new shortages has decreased (89 identified in 2025, per ASHP), the Colistin supply chain remains fragile with only 2-3 active manufacturers.

Prescribing Implications

The shortage creates several clinical challenges that prescribers should be aware of:

Empiric Therapy Considerations

Given inconsistent availability, providers should avoid empirically prescribing Colistin when culture data is pending unless the clinical scenario strongly suggests a polymyxin-only-susceptible organism. Premature use risks depleting limited supply for patients who have no alternatives.

Dose Optimization

Current dosing recommendations for Colistimethate Sodium are 2.5 to 5 mg/kg/day of colistin base activity, divided every 6-12 hours (IV/IM). Important considerations:

• Dosing should be based on ideal body weight in obese patients
• Renal dose adjustment is critical — the labeled maximum of 5 mg/kg/day assumes normal renal function (CrCl >80 mL/min)
• Loading doses are increasingly recommended in critically ill patients to achieve therapeutic concentrations faster, though this remains an area of active research
• Nephrotoxicity monitoring: BUN and creatinine should be checked at baseline and at least every 48 hours during therapy

Combination Therapy

Colistin monotherapy is associated with suboptimal outcomes for serious infections. Current evidence supports combining Colistin with agents such as Meropenem, Rifampin, or Amikacin based on susceptibility data. Combination therapy may also allow for lower Colistin doses, potentially reducing nephrotoxicity.

Current Availability Picture

As of early 2026, the U.S. supply of Colistimethate Sodium for injection (150 mg colistin base activity/vial) depends on three primary manufacturers:

• Xellia Pharmaceuticals — Copenhagen-based; key global API and finished dosage form supplier
• Par Pharmaceutical (Endo International) — U.S.-based; markets the branded Coly-Mycin M
• Hikma Pharmaceuticals — Generic supplier with intermittent availability

Hospital pharmacies should maintain direct communication with their wholesale distributors and consider participation in group purchasing organizations (GPOs) that may prioritize allocation during shortages.

Cost and Access

Colistin remains relatively affordable compared to newer anti-infective alternatives:

• Generic Colistimethate Sodium: ~$31-44 per vial (wholesale acquisition cost)
• Coly-Mycin M (brand): ~$31 per vial / ~$186 for 6 vials
• Ceftazidime-Avibactam (Avycaz): ~$500-1,000+ per day — significantly more expensive but more widely available
• Cefiderocol (Fetroja): ~$400-600 per day

For patients receiving outpatient parenteral antibiotic therapy (OPAT), cost can become a barrier. Colistin is typically covered under the medical benefit, but prior authorization may apply. Providers should work with social work and case management teams to verify coverage before discharge.

Tools and Resources for Providers

Several resources can help you manage the Colistin shortage more effectively:

• Medfinder for Providers: medfinder.com/providers — Search for Colistin availability across pharmacy networks. Purpose-built for clinical teams needing to locate medications quickly.
• ASHP Drug Shortages Center: Real-time shortage updates, alternative therapy recommendations, and estimated resupply timelines.
• IDSA Practice Guidelines: Infectious Diseases Society of America guidelines on the treatment of MDR gram-negative infections, including polymyxin stewardship recommendations.
• Hospital Antimicrobial Stewardship Programs: Leverage your institution's stewardship team to develop protocols for Colistin allocation during shortages.

For patient-facing resources you can share, consider directing patients to:

• Colistin Shortage Update: What Patients Need to Know
• How to Find Colistin in Stock Near You

Alternative Agents: A Quick Reference

When Colistin is unavailable, consider these alternatives based on susceptibility:

• Polymyxin B: Same drug class, similar spectrum. May have more predictable PK. Check availability — also subject to shortages.
• Ceftazidime-Avibactam (Avycaz): Active against many KPC-producing Enterobacteriaceae. Higher cost but generally available.
• Cefiderocol (Fetroja): Siderophore cephalosporin with broad gram-negative activity, including some Colistin-resistant strains.
• Imipenem-Cilastatin-Relebactam (Recarbrio): Option for certain CRE infections.
• Aminoglycosides (Amikacin, Tobramycin): May have activity based on susceptibility; consider for combination therapy.

For a patient-facing comparison, see Alternatives to Colistin.

Looking Ahead

The antimicrobial pipeline for MDR gram-negative infections is more active than it has been in decades, but near-term supply of Colistin remains uncertain. Key developments to watch:

• Potential new generic Colistimethate Sodium approvals that could increase supply diversity
• Expanded indications for newer agents like Cefiderocol and Imipenem-Relebactam that may reduce polymyxin reliance
• Legislative efforts (PASTEUR Act and similar initiatives) designed to incentivize antibiotic manufacturing
• Global antimicrobial resistance surveillance programs informing more targeted use of last-resort agents

Final Thoughts

The Colistin shortage is a supply-side problem compounded by an epidemiologic trend we cannot ignore: antimicrobial resistance is growing faster than antibiotic production capacity. As prescribers, our role is to steward existing supply, stay informed about alternatives, and leverage tools like Medfinder for Providers to help patients access the treatments they need.

For additional clinical resources, see our provider guides:

• How to Help Your Patients Find Colistin in Stock
• How to Help Patients Save Money on Colistin