Legal status · United States
Is Efimosfermin alfa legal in the United States?
No. Efimosfermin alfa is not approved for any medical use in the United States; its classification is "Investigational, not approved". Lawful access is limited to registered clinical trials. "Research use only" labeling on vials sold online does not make human use lawful. Human evidence to date: Moderate.
Efimosfermin alfa in the United States at a glance
| Classification | Investigational, not approved |
|---|---|
| FDA approval status | Investigational; Breakthrough Therapy designation |
| Evidence level | Moderate (research strength: Moderate) |
| Reviewed | Sep 2026 |
Classification and note come from the Efimosfermin alfa profile, checked against U.S. Food and Drug Administration (FDA) listings at the reviewed date.
What this means
- 01
Efimosfermin alfa is being studied in registered clinical trials but has not received FDA marketing approval in the United States.
- 02
Lawful human access is limited to trial participation or a formal early-access scheme where one exists; there is no pharmacy product to prescribe.
- 03
Vials sold online "for research use only" are not trial material, and that label does not make human use lawful.
What Efimosfermin alfa is
GSK's once-monthly FGF21 analog, acquired for $1.2 billion upfront, with FDA Breakthrough Therapy designation for MASH and Phase 2 results published in 2026.
Efimosfermin is an engineered FGF21 variant with a half-life long enough for monthly injection, the only monthly FGF21 in development. Its Phase 2 in F2/F3 MASH showed histologic benefit and good tolerability over 24 weeks, earning Breakthrough Therapy status from the FDA and PRIME from the EMA.
Mechanism: Long-acting FGF21 receptor agonism that reduces liver fat, inflammation and fibrosis.
Regulatory history: Investigational; Breakthrough Therapy designation
How FDA treats this kind of product
Approves prescription drugs by indication and polices unapproved products, including peptides sold online. Compounding pharmacies may prepare some compounds under a prescription when the FDA places them on a permitted bulk-substances category.
The classification above is the The Longevity Archive reading of U.S. Food and Drug Administration listings for Efimosfermin alfa at the reviewed date, not a legal opinion. Rules change, and importing, prescribing and possessing a compound can each be treated differently. Check the regulator directly before acting on anything here.
Efimosfermin alfa in other countries
Frequently asked questions
Is Efimosfermin alfa legal in the United States?
No. Efimosfermin alfa is not approved for any medical use in the United States; its classification is "Investigational, not approved". Lawful access is limited to registered clinical trials. "Research use only" labeling on vials sold online does not make human use lawful. Human evidence to date: Moderate.
Can I buy Efimosfermin alfa in the United States?
No approved product exists to buy. In the United States Efimosfermin alfa is classified as "Investigational, not approved", so there is no licensed pharmacy product. Vendors selling it "for research use only" are not selling it for human use, and that label does not change its legal status. This site does not list or recommend vendors.
Is Efimosfermin alfa FDA approved?
No. FDA status: Investigational; Breakthrough Therapy designation. Current US classification: "Investigational, not approved". Evidence level: Moderate.
Related compounds in the United States
Full research profile
Mechanism, cited studies, FDA status and the full legal summary for Efimosfermin alfa live on its compound profile.
Efimosfermin alfa profileThis page is general information about the regulatory status of Efimosfermin alfa in the United States, current as of Sep 2026. It is not legal advice, and classifications change; check U.S. Food and Drug Administration directly or consult a lawyer for a specific situation. Educational use only. This database summarizes published research. It is not medical advice and contains no dosing protocols or recommendations for personal use. The Longevity Archive has no vendor relationships and does not recommend where to buy anything.