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

Gentamicin, a foundational aminoglycoside antibiotic, is a critical agent in the management of serious gram-negative infections across virtually every inpatient specialty. Its availability is rarely taken for granted by experienced clinicians or hospital pharmacists — and for good reason. As a sterile injectable generic, gentamicin sits in the category of drugs most structurally vulnerable to supply chain disruptions.

This clinical briefing summarizes the current shortage status, the underlying supply chain vulnerabilities, formulary-level alternatives, and strategies for managing patients when gentamicin is not available or in limited supply.

Current Shortage Status (2026)

As of 2026, gentamicin does not have an active listing on the FDA Drug Shortage Database at the national level. However, institutional pharmacies continue to report intermittent back-order situations for specific vial sizes and concentrations, particularly the 10 mg/mL concentration in larger bag sizes used for extended-interval dosing regimens.

Prescribers should be aware that the absence of an active FDA shortage designation does not guarantee uninterrupted supply at the facility or regional level. The GAO reported in April 2025 that drug shortages tracked by the FDA as of mid-2024 numbered 102 active shortages, with sterile injectables remaining disproportionately affected. Gentamicin's profile — low-margin generic, few manufacturers, complex production requirements — keeps it perpetually in the at-risk category.

Clinical Context: Why Gentamicin Availability Matters

Gentamicin is not merely a treatment option — in certain clinical contexts, it is difficult to replace without meaningful tradeoffs:

Endocarditis synergy therapy: For streptococcal or enterococcal endocarditis, gentamicin is specifically preferred for synergistic therapy over other aminoglycosides due to the weight of clinical evidence. Other aminoglycosides have less clinical experience in this indication.

Empirical gram-negative coverage: Gentamicin remains first-line or co-first-line for empirical gram-negative coverage in sepsis, complicated UTIs, and nosocomial infections at institutions with low aminoglycoside resistance rates.

Ophthalmic and topical applications: Gentamicin ophthalmic and topical products are widely used in outpatient settings. Supply disruptions to these formulations can affect large patient volumes simultaneously in outpatient ophthalmology and dermatology practices.

Formulary Alternatives When Gentamicin Injectable Is Unavailable

In the event of gentamicin injectable shortage, the following alternatives should be considered at the institutional formulary level:

Tobramycin (IV/IM): The most direct aminoglycoside substitute. Comparable spectrum, nearly equivalent pharmacokinetics, and similar TDM requirements. Slightly superior activity against P. aeruginosa but less evidence for endocarditis synergy. Appropriate for most gentamicin indications except endocarditis synergy where clinical data specifically favor gentamicin.

Amikacin (IV/IM): Broader spectrum reserved for gentamicin/tobramycin-resistant organisms. Dosing differs (15-20 mg/kg/day vs. 5-7 mg/kg/day for gentamicin). Appropriate when resistance is confirmed or strongly suspected. Higher cost.

Fluoroquinolones (IV ciprofloxacin, levofloxacin): Acceptable non-aminoglycoside alternatives for gram-negative coverage when local resistance patterns permit. Avoid ototoxicity/nephrotoxicity of aminoglycosides. Rising resistance rates limit empirical use in some institutions.

Extended-spectrum beta-lactams: Piperacillin-tazobactam, cefepime, or meropenem can be used based on organism and susceptibility data when aminoglycoside avoidance is preferred due to renal function or shortage.

TDM Considerations When Switching Aminoglycosides

When substituting tobramycin for gentamicin, prescribers should note:

Tobramycin uses the same mg/kg extended-interval dosing as gentamicin (5-7 mg/kg once daily for empirical therapy in adults with normal renal function).

Therapeutic drug monitoring (TDM) protocols are essentially identical — use your institution's Hartford nomogram or Hartford-adapted protocols for tobramycin just as for gentamicin.

Target peak and trough levels, or AUC targets if your institution uses Bayesian TDM, remain the same for tobramycin as for gentamicin.

Nephrotoxicity and ototoxicity monitoring protocols should be maintained regardless of which aminoglycoside is used.

Outpatient Gentamicin Prescriptions: Helping Patients Access Their Medication

For ophthalmic and topical gentamicin prescriptions, patients may face stock issues at their local pharmacy. Providers can direct patients to medfinder.com/providers — a tool that calls nearby pharmacies to find which ones have the medication in stock. This reduces patient burden and decreases prescription abandonment due to stock issues.

When writing prescriptions for outpatient ophthalmic or topical gentamicin, consider writing for both the solution and ointment if clinically interchangeable — this gives the pharmacist and patient more options if one form is unavailable.

Institutional Preparedness Recommendations

To minimize patient impact from gentamicin supply disruptions, consider the following institutional-level strategies:

Maintain approved institutional gentamicin alternatives in your formulary (tobramycin IV, amikacin IV) with pre-approved dosing conversion protocols.

Create standing guidance for your pharmacy staff on when and how to substitute tobramycin for gentamicin without requiring a new physician order.

Communicate gentamicin shortage risk proactively to your infectious disease team, hospitalists, and ICU staff so they can adjust empirical protocols as needed.

Monitor the ASHP Drug Shortage Resource Center and FDA Drug Shortage Database for early warning of emerging supply issues.

For more on helping your patients access gentamicin when their pharmacy is out of stock, see our

provider's guide to helping patients find Gentamicin in stock.