Follistatin-344

What is follistatin-344, and is it FDA-approved?

Follistatin is a myostatin-inhibiting protein; while no approved pharmaceutical formulation exists, it circulates on the black market, mostly labeled follistatin 344 [1]. It is not on FDA's Category 1, 2 or 3 compounding lists, and it is prohibited at all times under the 2026 WADA list as a myostatin-binding protein [4]. When researchers tested 17 products sold as follistatin-344, only nine actually contained follistatin, and all nine of those contained a His-tagged version along with a high degree of oligomers [1].

Is there human evidence for injected follistatin-344?

No clinical trial of injected follistatin-344 was found in our search as of September 2026; the only human study identified used gene therapy, not an injection of the protein itself, in six people with a muscle-wasting condition. Over one year, their six-minute walking distance improved by 56.0 meters, compared with a 25.8-meter decline in eight untreated people [3].

What risks have been reported with follistatin-344 injections?

A case series identified 11 male bodybuilders, mean age 36.8 years, who developed an eye condition, central serous chorioretinopathy, after high-dose subcutaneous follistatin-344 injections to increase muscle mass; the authors describe follistatin-344 injection as a possible risk factor for the condition [2]. Because only nine of the 17 tested products contained follistatin, some of the others held different growth-promoting peptides, and all nine that did contained a His-tagged form, buyers cannot know what they are actually injecting [1].