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

The ongoing insulin aspart shortage has created significant clinical challenges for endocrinologists, PCPs, and other providers who care for patients with diabetes. This guide summarizes the current shortage status, therapeutic alternatives, biosimilar landscape, and practical strategies to support your patients through access disruptions.

Current ASHP Shortage Status (Updated January 2026)

The American Society of Health-System Pharmacists (ASHP) first listed insulin aspart as an active drug shortage in November 2023. As of the most recent ASHP update on January 26, 2026, the shortage continues. The shortage is formulation-specific:

• Fiasp FlexTouch pen (NDC 00169-3204-15): In shortage since April 2024; intermittent availability, not fully resolved
• Fiasp PenFill cartridge (NDC 00169-3205-15): Generally available
• Fiasp 10 mL vial: Generally available in the US; some regional constraints
• Fiasp PumpCart: Variable; confirm with local pharmacies and pump manufacturers

Root Causes of the Shortage

Novo Nordisk attributed the FlexTouch pen shortage to manufacturing capacity constraints specific to the pen delivery device. The insulin drug substance itself has not been in shortage. Several market-level factors have amplified the impact:

• Pen device manufacturing bottleneck at Novo Nordisk facilities
• Discontinuation of Novo Nordisk unbranded insulin aspart (effective December 31, 2025), concentrating demand on brand products
• Rising insulin demand from growing US diabetes population (38+ million Americans with diabetes)
• Inherent complexity of biologic manufacturing — insulin cannot be rapidly scaled like small-molecule drugs

Pharmacokinetic Considerations When Switching From Fiasp

Fiasp's clinical distinction is its accelerated absorption profile driven by niacinamide (vitamin B3) in the formulation. Key pharmacokinetic points:

• Onset of appearance in bloodstream: ~2.5 minutes (Fiasp) vs. ~5.2 minutes (NovoLog)
• Time to maximum insulin concentration: approximately 63 minutes post-injection
• Duration of action: approximately 3–5 hours, similar to other rapid-acting analogs
• Dosing window: at meal start or within 20 minutes after starting a meal (vs. 5–10 minutes pre-meal for NovoLog)

When converting from Fiasp to standard insulin aspart (NovoLog) or a biosimilar, the initial dose change can be done unit-to-unit. The critical counseling point is pre-meal timing adjustment: patients must inject 5–10 minutes before eating rather than at meal start. For CSII patients, all pump parameters (basal rates, insulin-to-carb ratios, correction factors) should be reassessed.

Therapeutic Substitution Options

The following rapid-acting insulins may be considered as therapeutic substitutes for Fiasp:

• NovoLog (insulin aspart): Same active ingredient; unit-for-unit dose; pre-meal timing required; FlexTouch pen generally available in 2026
• Lyumjev (insulin lispro-aabc): Ultra-rapid, meal-start or within 20 minutes post-meal; closest functional equivalent for CSII patients; made by Eli Lilly
• Humalog (insulin lispro): Widely available; 15 minutes before meals or immediately after; available in U-100 and U-200
• Merilog (insulin aspart-szjj): FDA approved February 2025; insulin aspart biosimilar by Sanofi; pre-meal timing like NovoLog
• Kirsty (insulin aspart-xjhz): FDA approved July 2025; designated interchangeable; by Biocon/Viatris; pharmacist may substitute without a new prescription
• Apidra (insulin glulisine): Alternative molecule; within 15 minutes before or 20 minutes after starting a meal; vial and SoloStar pen available

Special Considerations for Insulin Pump Users

Fiasp is widely used in CSII systems because of its ultra-rapid onset. Providers should be aware that:

• Premature infusion-set changes were more common with Fiasp (44%) vs. standard insulin aspart (16.7%) in one study — educate patients transitioning back to NovoLog on this difference
• Maximum reservoir time for Fiasp is 6 days (vs. longer for some other insulins)
• Lyumjev is the most clinically similar alternative for CSII due to its ultra-rapid profile; verify pump compatibility before prescribing
• When switching CSII patients, always increase glucose monitoring frequency and review all pump settings with the patient

Prescribing Tips During the Shortage

To reduce access friction for your Fiasp patients:

1. Consider writing "Fiasp or NovoLog" on prescriptions during shortage periods to give pharmacists flexibility
2. When prescribing Fiasp specifically, note whether vial or PenFill cartridge is acceptable as an alternative delivery format if FlexTouch is unavailable
3. Counsel patients to refill prescriptions early (as soon as insurance allows) rather than waiting until they run out
4. Familiarize your practice with medfinder.com — it calls pharmacies to find insulin in stock and can help patients locate supply without spending hours on hold
5. Direct patients to Novo Nordisk's NovoCare program (1-866-310-7549) for both access assistance and savings programs

Helping Patients Navigate Cost During the Shortage

Access issues are compounded when patients are switching products and face formulary or prior authorization challenges. Key savings resources to share with patients:

• Novo Nordisk Savings Card: Commercially insured patients can pay as little as $35/month (up to 3 vials or 2 packs of pens)
• Novo Nordisk Patient Assistance Program (NovoCare): Free insulin for qualifying uninsured or underinsured patients; call 1-866-310-7549
• GoodRx/SingleCare: Discount cards can reduce Fiasp vial cost to approximately $63–$78 at participating pharmacies
• Medicare IRA cap: Medicare Part D patients pay no more than $35/month for covered insulins under the Inflation Reduction Act

For more clinical tools to help your patients find and afford medications, visit medfinder for providers.