Follistatin is a naturally occurring protein that binds and neutralises myostatin and activins, effectively releasing a brake on muscle growth. Follistatin-based therapies, including gene-therapy approaches, are investigational and not approved by any regulator. Because it inhibits myostatin, follistatin is prohibited in sport by WADA at all times.

Is Follistatin approved for medical use?

Follistatin is investigational: it is being studied in clinical research and is not an approved medicine. United States (FDA): Not approved for any indication; follistatin-based gene therapies have been studied only in early-phase clinical trials. European Union (EMA): No EMA marketing authorisation; not an approved medicine in the EU. Australia (TGA): Not on the Australian Register of Therapeutic Goods (ARTG); an unapproved substance with no registered therapeutic product.

Is Follistatin legal in Australia?

Follistatin in Australia (TGA): Not on the Australian Register of Therapeutic Goods (ARTG); an unapproved substance with no registered therapeutic product.

Is Follistatin banned in sport?

Follistatin under the World Anti-Doping Agency (WADA) code: Prohibited at all times under Section S4.3 (Agents preventing activin receptor IIB activation), which explicitly names follistatin among myostatin-binding proteins; gene-therapy delivery may additionally be captured under M3 (Gene and Cell Doping).

Endogenous activin-binding glycoprotein; myostatin/activin antagonist (studied as recombinant protein and via gene therapy, e.g., FS-344)

Follistatin

Investigationalaka FS-344, FST, Follistatin-344

Follistatin is an endogenous activin-binding glycoprotein that antagonises myostatin (GDF-8) and activins, and it has been studied as a way to increase muscle mass in muscle-wasting diseases. Human experience is limited to early-phase gene-therapy trials (for example, AAV-delivered follistatin for Becker muscular dystrophy and inclusion body myositis); no follistatin product is approved for any indication.

Mechanism

In plain terms, follistatin removes a natural stop signal that limits how much muscle can grow. Technically, it is a high-affinity binding protein that sequesters myostatin and activin, preventing them from activating activin type II receptors (ActRIIB) and the downstream Smad2/3 signalling that restrains muscle. By neutralising these ligands, follistatin permits increased muscle fibre growth in animal models, which is the rationale for follistatin gene therapy in muscular dystrophies. Human efficacy and long-term safety remain unestablished.

Regulatory Status by Region

United States (FDA)Not approved for any indication; follistatin-based gene therapies have been studied only in early-phase clinical trials.
Australia (TGA)Not on the Australian Register of Therapeutic Goods (ARTG); an unapproved substance with no registered therapeutic product.
European Union (EMA)No EMA marketing authorisation; not an approved medicine in the EU.
WADAProhibited at all times under Section S4.3 (Agents preventing activin receptor IIB activation), which explicitly names follistatin among myostatin-binding proteins; gene-therapy delivery may additionally be captured under M3 (Gene and Cell Doping).

See the full regulatory status matrix

Key Studies

Regulation of myostatin activity and muscle growth (demonstrating that follistatin overexpression blocks myostatin and increases muscle mass) (opens in a new tab) (Lee SJ, McPherron AC. Proc Natl Acad Sci U S A. 2001.)
A phase 1/2a follistatin gene therapy trial for Becker muscular dystrophy (opens in a new tab) (Mendell JR, et al. Mol Ther. 2015.)

Related Clinical Trials

Latest research

Rapamycin-sensitive mTORC1 signaling in the medial prefrontal cortex contributes to the antidepressant-like behavioral effects of shikimic acid in mice. (opens in a new tab)
Life sciences · Aug 5, 2026

See all recent Follistatin research

Common Questions

What is Follistatin?: Follistatin is a naturally occurring protein that binds and neutralises myostatin and activins, effectively releasing a brake on muscle growth. Follistatin-based therapies, including gene-therapy approaches, are investigational and not approved by any regulator. Because it inhibits myostatin, follistatin is prohibited in sport by WADA at all times.
Is Follistatin approved for medical use?: Follistatin is investigational: it is being studied in clinical research and is not an approved medicine. United States (FDA): Not approved for any indication; follistatin-based gene therapies have been studied only in early-phase clinical trials. European Union (EMA): No EMA marketing authorisation; not an approved medicine in the EU. Australia (TGA): Not on the Australian Register of Therapeutic Goods (ARTG); an unapproved substance with no registered therapeutic product.
How does Follistatin work?: In plain terms, follistatin removes a natural stop signal that limits how much muscle can grow. Technically, it is a high-affinity binding protein that sequesters myostatin and activin, preventing them from activating activin type II receptors (ActRIIB) and the downstream Smad2/3 signalling that restrains muscle.
Is Follistatin legal in Australia?: Follistatin in Australia (TGA): Not on the Australian Register of Therapeutic Goods (ARTG); an unapproved substance with no registered therapeutic product.
Is Follistatin banned in sport?: Follistatin under the World Anti-Doping Agency (WADA) code: Prohibited at all times under Section S4.3 (Agents preventing activin receptor IIB activation), which explicitly names follistatin among myostatin-binding proteins; gene-therapy delivery may additionally be captured under M3 (Gene and Cell Doping).