Comprehensive medication guide to Fiasp including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$50 copay with commercial insurance; Tier 2–3 on most plans; some plans require prior authorization or step therapy. Medicare Part D patients pay no more than $35/month under the Inflation Reduction Act insulin cap. Fiasp is subject to Medicare-negotiated pricing effective 2026.
Estimated Cash Pricing
$78–$388 retail for a 10 mL vial (100 units/mL); as low as $63–$78 with GoodRx or SingleCare coupons at participating pharmacies. FlexTouch pen packs range from $130–$350 without discounts.
Medfinder Findability Score
35/100
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Fiasp is a brand-name ultra-rapid-acting insulin manufactured by Novo Nordisk. Its active ingredient is insulin aspart — the same molecule found in NovoLog — but with the addition of niacinamide (vitamin B3), which accelerates absorption, and L-arginine for stability. Fiasp was FDA-approved on September 29, 2017, for improving glycemic control in adults and children with diabetes mellitus.
Fiasp appears in the bloodstream approximately 2.5 minutes after injection — about twice as fast as standard insulin aspart (NovoLog). This ultra-rapid onset allows Fiasp to be dosed at the start of a meal or up to 20 minutes after beginning to eat, giving patients with diabetes significantly more mealtime flexibility than conventional rapid-acting insulins.
Fiasp is available in four formats: FlexTouch prefilled pen (3 mL), PenFill cartridge (3 mL), 10 mL vial, and PumpCart cartridge (1.6 mL) for insulin pumps. All formulations contain 100 units/mL insulin aspart.
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Insulin aspart, the active ingredient in Fiasp, works by binding to insulin receptors on cells throughout the body, primarily in skeletal muscle and adipose (fat) tissue. Receptor binding triggers glucose transporter proteins (GLUT-4) to move to the cell surface, allowing glucose to flow from the bloodstream into cells where it is used for energy. Simultaneously, Fiasp signals the liver to stop producing and releasing additional glucose, further lowering blood sugar levels.
What makes Fiasp faster than NovoLog is niacinamide (vitamin B3), which causes local vasodilation at the injection site. This increases blood flow and speeds up the process of insulin hexamers breaking apart into absorbable monomers. The result: insulin appears in the bloodstream in approximately 2.5 minutes (vs. 5.2 minutes for NovoLog), reaches peak concentration at about 63 minutes post-injection, and has a total duration of action of approximately 3–5 hours.
At the molecular level, insulin aspart differs from natural human insulin by a single amino acid substitution: aspartic acid replaces proline at position B28. This modification reduces hexamer formation and allows faster dissolution and absorption at the injection site compared to regular human insulin.
100 units/mL — FlexTouch prefilled pen (3 mL)
Disposable prefilled pen; 5-pack; most convenient for daily subcutaneous injection; currently in intermittent shortage
100 units/mL — PenFill cartridge (3 mL)
Used with reusable NovoPen device; 5-pack; generally more available than FlexTouch pen
100 units/mL — 10 mL multi-dose vial
Used with standard U-100 insulin syringe; most widely available format; cost-effective
100 units/mL — PumpCart cartridge (1.6 mL)
Designed for compatible continuous subcutaneous insulin infusion (CSII) pump systems; max 4 days in pump
Finding Fiasp has been significantly more difficult since April 2024, when the Fiasp FlexTouch prefilled pen went into backorder due to manufacturing capacity constraints at Novo Nordisk. As of January 2026, the American Society of Health-System Pharmacists (ASHP) continues to list insulin aspart (including Fiasp) as an active drug shortage. The FlexTouch pen remains the hardest formulation to find, while PenFill cartridges and 10 mL vials have been more consistently available.
The shortage has been compounded by Novo Nordisk's discontinuation of its unbranded insulin aspart effective December 31, 2025, which pushed more patients toward brand Fiasp and NovoLog. Two biosimilars — Merilog (February 2025) and Kirsty (July 2025) — are entering the market and expected to ease supply pressure through 2026. Most experts expect gradual improvement as biosimilar production scales up, but intermittent shortages may continue through mid-2026.
If you're struggling to find Fiasp in stock near you, medfinder calls pharmacies in your area to check which ones can currently fill your Fiasp prescription — so you don't have to spend hours on hold. Independent pharmacies and mail-order options (Express Scripts, OptumRx, CVS Caremark) often have better supply than chain retail stores.
Fiasp is not a controlled substance and has no DEA scheduling. Any licensed healthcare provider with prescribing authority can write a Fiasp prescription without special registration or restrictions. This makes it broadly accessible across clinical settings.
Providers who commonly prescribe Fiasp include:
Fiasp can be prescribed via telehealth. Because it is not a controlled substance, telehealth platforms can prescribe it during a virtual visit for patients with an established diabetes diagnosis and recent blood glucose data. Platforms offering diabetes telehealth services include Teladoc, MDLive, and diabetes-specialized programs.
No. Fiasp (insulin aspart) is not a controlled substance. It is not scheduled by the DEA. Any licensed healthcare provider — including physicians, nurse practitioners, and physician assistants — can prescribe Fiasp without any special DEA registration or prescribing restrictions.
Because Fiasp is not controlled, there are no limits on prescription quantities, no restrictions on refill frequency beyond normal insurance rules, and no special pharmacist verification requirements. Fiasp can also be prescribed via telehealth without the additional restrictions that apply to controlled substance medications.
The most common side effects of Fiasp include:
Serious side effects requiring immediate medical attention:
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NovoLog (insulin aspart)
Same active ingredient as Fiasp without niacinamide; slightly slower onset (5.2 min vs 2.5 min); dose at the same units 5-10 min before meals; FlexTouch pen generally available in 2026
Lyumjev (insulin lispro-aabc)
Ultra-rapid insulin lispro by Eli Lilly; can also be dosed at meal start or within 20 min after; best functional equivalent for CSII users; different active molecule
Humalog (insulin lispro)
Widely available rapid-acting insulin by Eli Lilly; inject 15 min before or right after meals; available in U-100 and U-200; strong backup option
Kirsty (insulin aspart-xjhz)
FDA-approved interchangeable biosimilar (July 2025) by Biocon/Viatris; same active ingredient as Fiasp but without niacinamide; pharmacist can substitute without new Rx
Merilog (insulin aspart-szjj)
FDA-approved biosimilar (February 2025) by Sanofi; insulin aspart without niacinamide; pre-meal timing like NovoLog; growing availability through 2026
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Thiazolidinediones (pioglitazone, rosiglitazone)
majorIncreases risk of fluid retention and heart failure; monitor for rapid weight gain, edema, shortness of breath
Monoamine oxidase inhibitors (MAOIs)
majorSignificantly potentiates hypoglycemic effect; major risk of severe low blood sugar
Corticosteroids (prednisone, dexamethasone)
majorReduces Fiasp effectiveness; significantly raises blood sugar; dose adjustment usually required during steroid courses
Beta-blockers (metoprolol, propranolol, atenolol)
moderateMay mask warning symptoms of hypoglycemia (racing heart, trembling); non-selective beta-blockers can prolong hypoglycemia
SSRIs (fluoxetine, sertraline, paroxetine)
moderateMay enhance insulin's blood-sugar-lowering effect; increased hypoglycemia risk
ACE inhibitors (lisinopril, enalapril)
moderateMay enhance insulin sensitivity; monitor blood glucose when starting or adjusting ACE inhibitor
Alcohol
moderateVariable effect; may increase hypoglycemia risk by inhibiting liver glucose production; never skip meals when drinking on Fiasp
Atypical antipsychotics (olanzapine, clozapine)
moderateMay cause insulin resistance and reduce Fiasp effectiveness; may require dose increases
Fiasp is a highly effective ultra-rapid-acting insulin that gives people with type 1 and type 2 diabetes greater flexibility in mealtime dosing. Its niacinamide-enhanced absorption — delivering insulin to the bloodstream in about 2.5 minutes — makes it particularly valuable for insulin pump users, those with unpredictable eating schedules, and anyone focused on tightly controlling post-meal blood sugar spikes.
Access challenges in 2026 are real but manageable. The Fiasp FlexTouch pen remains in intermittent shortage, but vials and PenFill cartridges are generally available. Two new biosimilars (Merilog and Kirsty) are entering the market, and Medicare-negotiated prices took effect in 2026. Commercially insured patients can access Fiasp for as little as $35/month with the Novo Nordisk Savings Card, and uninsured patients may qualify for free insulin through the NovoCare Patient Assistance Program.
If you're having trouble finding Fiasp at your pharmacy, medfinder calls pharmacies near you to find which ones have your prescription in stock — saving you the frustration of calling around yourself. Never ration insulin; if you're running low and can't find Fiasp, contact your prescriber immediately about bridge options.
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Our medication guides are researched and written to help patients make informed decisions. All content is reviewed for accuracy and updated regularly. Learn more about our standards
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