FGF21 vs Efruxifermin
Written by Aaron CuhaReviewed Sep 2026
The short answer
The hormone and its lab made copy. The body releases FGF21 when fasting, and it lasts only hours. That is why every drug version is a changed protein. It is also why lifespan results in mice bred to make extra FGF21 do not carry over to people taking a copy for liver disease.
- FGF21 people
- 350
- FGF21 nulls
- 0
- Efruxifermin people
- 181
- Efruxifermin nulls
- 1
Dose
No human dose established
Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose.
2 completed trials, 350 people given it
Dose
No human dose established
Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose.
1 completed trial, 181 people given it
First-hand reports are counted on each profile and never added together. This page sets two published records side by side. It does not pick a winner.
Column A
FGF21Fibroblast growth factor 21 (native hormone)
FGF21 is a hormone your liver makes when you fast, eat sugar or eat less protein. Lab-built versions healed liver scarring in two mid-sized studies of 222 and 128 people with fatty liver disease. Longer life has only been seen in mice bred to make extra FGF21.
Column B
EfruxiferminEfruxifermin (EFX, AKR-001)
A weekly shot that copies FGF21, a liver hormone. In people with cirrhosis from fatty liver disease, it missed its main test at 36 weeks. By 96 weeks, scarring improved in 29 percent against 11 percent on a dummy shot. Three large final-stage studies are running.
Side by side, on the facts we can check
| What we compare | FGF21 | Efruxifermin |
|---|---|---|
| Category | Metabolic | Metabolic |
| FDA status | Not FDA-approved. Natural FGF21 is not a drug. No lab-made version of FGF21 (efruxifermin, pegozafermin, efimosfermin) was listed in the FDA drug database (Drugs@FDA) on 11 September 2026. Efruxifermin and pegozafermin are in final-stage studies. | Investigational; in final-stage studies |
| Half-life | Not reported | Weekly subcutaneous dosing |
| Molecular weight | 22,300 Da precursor (209 residues, UniProt Q9NSA1); mature secreted chain residues 29 to 209, 181 amino acids | 92,108 Da (Fc-FGF21 fusion protein) |
| How it works | In people, FGF21 rises soon after eating sugar. A common version of the FGF21 gene goes with eating more sweets and drinking more alcohol. Exercise training raises FGF21 in the blood. Lab-built versions, given as a weekly shot, cut liver fat, heal scarring in liver samples and lower blood fats in people with fatty liver disease. Nausea and diarrhoea are the main side effects. A 2026 review asks whether those effects come from the whole body or just the liver. In mice, fasting makes the liver release FGF21. FGF21 then drives fat burning and the making of ketones. It makes the body respond better to insulin. It turns down growth hormone and causes bone loss. It works through a receptor called FGFR1c, but only where beta-klotho is present. That limits it to fat, liver and certain brain areas. 2025 mouse work found FGF21 reverses fatty liver disease through both the brain and the liver. It also made obese mice live longer, without slowing their growth. | It turns on the FGF21 receptor for a long time. That lowers liver fat, helps the body use insulin and reduces scarring. |
| Studies in people | 4 | 2 |
| Evidence | Moderate: 2 completed trials, 350 people given it | Moderate: 1 completed trial, 181 people given it |
| Legal status, US | Investigational, not approved | Investigational, not approved |
Frequently asked questions
What is the difference between FGF21 and Efruxifermin?
FGF21: FGF21 is a hormone your liver makes when you fast, eat sugar or eat less protein. Lab-built versions healed liver scarring in two mid-sized studies of 222 and 128 people with fatty liver disease. Longer life has only been seen in mice bred to make extra FGF21. Efruxifermin: A weekly shot that copies FGF21, a liver hormone. In people with cirrhosis from fatty liver disease, it missed its main test at 36 weeks. By 96 weeks, scarring improved in 29 percent against 11 percent on a dummy shot. Three large final-stage studies are running.
Which has stronger research evidence, FGF21 or Efruxifermin?
Each compound gets a band worked out from facts we counted, with the math shown. FGF21 is Moderate (2 completed trials, 350 people given it). Efruxifermin is Moderate (1 completed trial, 181 people given it). That counts how much has been done in people. It does not rate whether either one works, and neither one is called the winner.
Are FGF21 and Efruxifermin FDA-approved?
FGF21: Not FDA-approved. Natural FGF21 is not a drug. No lab-made version of FGF21 (efruxifermin, pegozafermin, efimosfermin) was listed in the FDA drug database (Drugs@FDA) on 11 September 2026. Efruxifermin and pegozafermin are in final-stage studies.. Efruxifermin: Investigational; in final-stage studies.
Related posts
Blog articles that cover FGF21 or Efruxifermin, newest first.
Reviewed Sep 2026. This page puts two published records side by side. It is for learning, and it is not medical advice. When this site shows a dose, it is the dose a trial or a clinic actually used, or what people say they did, with the source attached. None of it tells you what to take.