Follistatin Dosage: Common Protocol, Trial Data and Calculator
The protocol commonly used for "FST-344," labelled as common practice, plus the human gene-therapy and mouse-protein doses actually published.
The short version
No human trial has set a dose for the injected recombinant follistatin protein sold online as "FST-344". The protocol most often used is 100-500 mcg by subcutaneous injection, 2 to 4 times a week, for 8-16 weeks. That is common practice, not something a trial established. The human trial dosing data is for a different product: a one-time viral-vector gene therapy injected into muscle, tested in two small trials. A separate mouse study injected the protein daily for 13 weeks.
- The protocol most often used is 100-500 mcg subcutaneously, 2-4 times a week, over 8-16 weeks - common practice, not trial-established.
- No human trial has dosed the injected recombinant protein sold as "FST-344."
- The only human trial dosing data is a one-time AAV gene-therapy injection, a different product and route.
- A mouse study dosed the actual protein (a different isoform) daily for 13 weeks.
- Reconstitution and injection-volume arithmetic belongs on the dosage calculator, not this page.
Follistatin has no trial-established dose, because no human trial has dosed the injected recombinant protein sold online as “FST-344”. This page gives the protocol most often used in practice, labelled as common practice. It also gives the doses used in two small human gene-therapy trials and one mouse protein study. For the mechanism and legal status, see the main Follistatin guide.
US legal status - Research use only
Not FDA-approved for any use, and not a dietary supplement. FDA named Follistatin directly in an April 2020 warning letter, stating it failed the conditions for lawful section 503A compounding.
Follistatin dosage: the common protocol
The protocol most often used is 100-500 mcg by subcutaneous injection, 2 to 4 times a week, over roughly 8-16 weeks. No human trial has dosed the injected protein sold online. The studies that do exist used a gene therapy and a mouse experiment, covered below.
Common protocol
What is commonly used, not a dose established in trials. No regulator has set a dose for Follistatin. Sources differ, so the ranges below span them.
- Dose per administration
- 100-500 mcg
- How often
- 2 to 4 times a week
- Route
- Subcutaneous injection
- Cycle length
- 8-16 weeks
- Common vial size
- 1 mg
- Timing
- Sources disagree: one describes morning dosing on protocol days, another suggests injecting 30-60 minutes before resistance training, calling that timing theoretical rather than evidence-based.
Sources differ materially on both amount and frequency - one describes 100 mcg four times a week, another 200-500 mcg two to three times a week with a 50-100 mcg titration start. Both explicitly call this a research convention extrapolated from preclinical and community sources, not a validated human protocol, and one warns against exceeding 500 mcg, citing reports of ocular complications.
Plan a cycle in the protocol builder or work out injection volume in the dosage calculator.
The common Follistatin dose is 100-500 mcg, 2 to 4 times a week. From a 1 mg vial mixed with 1 mL of bacteriostatic water, 300 mcg is 30 units (0.3 mL) on a U-100 insulin syringe.
Follistatin 1 mg vial: units per dose
Full 1 mg vial page: mixing, doses per vial, how long it lasts →
| Water added | Concentration | 1 unit = | 100 mcg | 300 mcg | 500 mcg |
|---|---|---|---|---|---|
| 1 mL | 1 mg/mL | 10 mcg | 10 units | 30 units | 50 units |
| 2 mL | 0.5 mg/mL | 5 mcg | 20 units | 60 units | 100 units |
| 3 mL | 0.33 mg/mL | 3.33 mcg | 30 units | 90 units | over 100 units |
All Follistatin vial sizes: 1 mg
Units are on a standard U-100 insulin syringe (100 units = 1 mL), rounded to the nearest half unit - half-unit marks are on 0.3 mL syringes. Water volumes are examples: more water means more units per dose, not more doses per vial. For any other vial or dose, use the calculator below.
How many 1 mg vials a cycle takes
| Scenario | Dose | Doses a week | Weeks | Total | 1 mg vials |
|---|---|---|---|---|---|
| Low end of the common protocol | 100 mcg | 2 | 8 | 1.6 mg | 2 |
| High end of the common protocol | 500 mcg | 4 | 16 | 32 mg | 32 |
Whole vials, rounded up. Plan a cycle with your own numbers in the protocol builder. Keep mixed vials cold and use them within the window in how long reconstituted peptides last; where to inject: subcutaneous injection sites.
Follistatin doses used in human studies
The two published human trials of raised follistatin did not inject the recombinant protein. They delivered a viral vector once into muscle, so the patient’s own cells would produce follistatin. It is a different product, dosed in vector genomes per kilogram, not milligrams of protein.
| Trial | Population | Product & route | Dose | Course |
|---|---|---|---|---|
| Becker muscular dystrophy Mendell 2015 - Mendell JR, Sahenk Z, Malik V et al. A phase 1/2a follistatin gene therapy trial for becker muscular dystrophy. Mol Ther. 2015;23(1):192-201., in the references below | 6 adults, Cohort 1 (n=3) and Cohort 2 (n=3) | AAV1.CMV.FS344, bilateral intramuscular quadriceps injection | Cohort 1: 3x10^11 vg/kg/leg. Cohort 2: 6x10^11 vg/kg/leg | Single administration |
| Sporadic inclusion body myositis Mendell 2017 - Mendell JR, Sahenk Z, Al-Zaidy S et al. Follistatin Gene Therapy for Sporadic Inclusion Body Myositis Improves Functional Outcomes. Mol Ther. 2017;25(4):870-879., in the references below | 6 adults, treated (vs. 8 untreated comparators) | rAAV1.CMV.huFS344, bilateral intramuscular quadriceps injection | 6x10^11 vg/kg | Single administration, plus a supervised exercise regimen |
The Becker trial reported no adverse effects. It found a mixed change in 6-minute-walk distance across the six patients and histological signs of muscle benefit, more pronounced at the higher dose.
The inclusion body myositis trial reported an annualized 6-minute-walk change of +56.0 meters per year in the treated group, against a 25.8-meter decline in untreated comparators. Other researchers later disputed that result in the same journal. They argued the reported primary outcome and statistical method differed from what was registered before the trial started. The dispute is about how the walking result was analysed, not about the vector dose. See the main guide for details.
Doses used in animal studies
A 2013 mouse study Gangopadhyay 2013 - Gangopadhyay SS. Systemic administration of follistatin288 increases muscle mass and reduces fat accumulation in mice. Sci Rep. 2013;3:2441., in the references below injected recombinant follistatin288 subcutaneously, once daily, for 13 weeks. This is a shorter isoform than the FST344 splice variant vendors name. The mice were 8 weeks old (C57BL/6), split into four groups of six, and given 0, 10, 30 or 100 micrograms per animal per day. The 100-microgram group showed the largest dose-dependent increase in lean and muscle mass and the largest decrease in body fat mass. The injected protein was detectable in circulation throughout.
What is not established
- No dose for the injected protein has been tested in any human trial. The two human trials above used a different product (a gene-therapy vector). The mouse study used a different species and isoform. The common protocol above is compiled from circulating practice, not from a trial.
- No repeated human dosing schedule has been studied. Both human trials were a single, one-time injection.
- No human half-life is established. The main guide explains why this site does not publish one for the injected protein.
How to reconstitute Follistatin
Turning a target amount into an injection volume depends on a specific vial’s concentration and diluent, which this page cannot know. The dosage calculator handles that arithmetic. It does not supply or endorse a dose.
Who should not use it
No FDA-reviewed contraindication list exists for any injectable follistatin product. Follistatin binds activin broadly, and activin has established roles in reproductive hormone regulation outside muscle. So there is no reviewed guidance for anyone pregnant, breastfeeding, or managing a hormonal, reproductive or other diagnosed condition. There is also no published human safety data for the injected protein at any dose.
Follistatin side effects and risks
FDA has already acted on this substance. A 2020 warning letter names Follistatin among bulk drug substances a compounding pharmacy was told it could not lawfully use. Follistatin is also a named substance on the WADA Prohibited List (see the main guide).
Beyond the regulatory record, the central risk is the absence of data. No long-term human safety study exists for the injected protein, and no human half-life is established. Material sold as a research chemical carries no independently verified purity, identity or concentration.
Related
Follistatin dosage calculator
Preset to a 1 mg vial and 100 mcg, the low end of the common protocol. Enter your own vial size, water and dose to get the syringe units to draw.
Your vial
Printed on the vial. There is no standard size - enter what yours says.
This changes how much you draw - never how many doses the vial holds.
100 units per mL. 1 unit = 0.01 mL. This is what almost every insulin syringe sold is, in every barrel size.
Capacity only. A 1 mL U-100 syringe holds 100 units - the scale decides that, not the barrel.
Draw this much
= 0.2 mL on a 1 mL U-100 syringe
- Concentration
- 500 mcg/mL
- Exact volume
- 0.2 mL
- Dose you actually get
- 100 mcg
- Doses per vial(unaffected by water volume)
- 10
Where to buy Follistatin for research
Each vendor is checked against my vendor checklist.
I don't list a vendor for Follistatin yet. Before buying from anyone, work through the vendor checklist.
Common questions
What is the usual follistatin dose?
The protocol most often used is 100-500 mcg by subcutaneous injection, 2 to 4 times a week, over roughly 8-16 weeks. That is common practice compiled from circulating protocols, not a dose any human trial established. No trial has dosed the injected recombinant protein sold online as "FST-344".
What dose of follistatin has been used in human studies?
No human study has dosed the injected recombinant protein sold online. The human dosing record is for a different product, a one-time viral-vector gene therapy. Six adults with Becker muscular dystrophy received a single bilateral intramuscular injection of AAV1.CMV.FS344. The dose was 3x10^11 vector genomes per kilogram per leg in the first cohort and 6x10^11 in the second. Six adults with sporadic inclusion body myositis separately received a single bilateral intramuscular injection of the same vector at 6x10^11 vector genomes per kilogram. Both were one-time gene-delivery doses, not a repeated protein-injection schedule.
Is the gene-therapy dose the same thing as an "FST-344" dose?
No. The gene therapy delivers a viral vector once, so the patient's own muscle cells make follistatin over time. A vial sold online is a recombinant protein, injected directly and repeatedly. Vector genomes per kilogram and a milligram or microgram protein dose are not comparable units, and no study has translated one into the other.
What dose was used in animal studies?
A 2013 mouse study injected recombinant follistatin288, a shorter isoform than the "FST-344" sold online, subcutaneously once a day for 13 weeks. Four groups received 0, 10, 30 or 100 micrograms per animal per day. The 100-microgram group showed the largest increase in lean and muscle mass and the largest decrease in fat mass. That is a mouse dose, in micrograms per animal, of a different isoform than the marketed product. There is no accepted method for converting it into a human dose.
Is there a dosing protocol for the injectable "FST-344" product?
No published human study has dosed that product, but a protocol circulates in practice. It is 100-500 mcg by subcutaneous injection, 2 to 4 times a week, over roughly 8-16 weeks, compiled from sources this page checked. That is common practice, not a finding from a trial, paper or regulator.
How do I work out reconstitution and injection volume?
That is arithmetic about a specific vial's concentration and diluent volume, not a dosing decision, and this page cannot know your vial. The dosage calculator handles that math. It does not supply or endorse a dose.
Who should not use follistatin?
No FDA-reviewed contraindication list exists, because follistatin has never gone through that review for any injectable product. Follistatin also binds activin broadly, and activin helps regulate reproductive hormones outside muscle. So there is no reviewed guidance for anyone pregnant, breastfeeding, or with a hormonal, reproductive or other diagnosed condition.
What are the main risks?
The central risk is the absence of data. No published human safety study exists for the injected protein at any dose, and no human half-life has been established. FDA named follistatin in a 2020 warning letter as failing the conditions for lawful compounding. Material sold as a research chemical also carries no independently verified purity, identity or concentration.
When should I stop and get medical care?
In the US, call 911 for a severe allergic reaction, chest pain, fainting, or any symptom that feels dangerous. If you have taken an unknown or excessive amount of anything sold as follistatin or "FST-344", call Poison Control at 1-800-222-1222. Verify that number yourself at poisonhelp.hrsa.gov or poison.org. None of this is a substitute for a clinician who knows your history.
References (4 sources)
Bibliographic detail is fetched from PubMed, not written by me - so a citation here cannot drift from the paper it names. Study design comes from PubMed's own tags rather than my judgement.
- 1.Mendell JR, Sahenk Z, Malik V et al. A phase 1/2a follistatin gene therapy trial for becker muscular dystrophy. Mol Ther. 2015;23(1):192-201.Clinical trialPMID 25322757full text
- 2.Mendell JR, Sahenk Z, Al-Zaidy S et al. Follistatin Gene Therapy for Sporadic Inclusion Body Myositis Improves Functional Outcomes. Mol Ther. 2017;25(4):870-879.StudyPMID 28279643full text
- 3.Gangopadhyay SS. Systemic administration of follistatin288 increases muscle mass and reduces fat accumulation in mice. Sci Rep. 2013;3:2441.StudyPMID 23942549full text
- 4.FDA warning letter to Tailor Made Compounding LLC (594743), naming Follistatin among bulk drug substances that fail the section 503A compounding conditions- US Food and Drug Administrationregulatory