Andarine (S-4) Dosage: What the Evidence Actually Shows

Key takeaways

What Is Andarine (S-4)?

Andarine, also known by its developmental code names GTx-007 and S-4, is a nonsteroidal selective androgen receptor modulator (SARM). It emerged from a line of research in which acryl propionamide compounds related to the antiandrogens bicalutamide and hydroxyflutamide were structurally modified in the search for tissue-selective androgen receptor agonists. Andarine demonstrated high androgen receptor binding affinity and anabolic specificity in early rat studies, which helped establish it as one of the first compounds in this new pharmacological class.

GTx, Inc., the company that developed andarine, redirected its clinical program toward a related, more advanced compound, enobosarm (ostarine, GTx-024, S-22). Enobosarm went on to be tested in Phase I, II, and III human trials, with published results on lean body mass and physical function in elderly men, postmenopausal women, and cancer patients. Andarine itself does not have equivalent published human trial data.

Because andarine's pharmaceutical development did not progress to that stage, it is not an approved drug anywhere in the world. In the United States, andarine is classified as an investigational, unapproved drug, and the FDA has stated that supplements marketed as containing it are illegal. It is sold today only as an unregulated "research chemical" or as an ingredient, declared or undeclared, in some bodybuilding products, neither of which is a legal channel for human consumption in the United States or most other jurisdictions.

Is There an Official or Clinically Established Andarine Dosage?

No. Unlike enobosarm, for which dose-ranging Phase I and Phase II human trials have been published with defined milligram doses, measured pharmacokinetics, and monitored safety endpoints, no peer-reviewed human pharmacokinetic or dose-ranging study of andarine has been published. What does exist is preclinical rat and dog pharmacokinetic data. A rat study reported linear pharmacokinetics for andarine after intravenous and oral dosing, and a companion study in dogs reported a mean clearance of 4.6 mL/min/kg and a mean half-life of about 200 minutes (roughly 3.3 hours). The commonly repeated figure of a '4-hour half-life' traces back to this preclinical animal data rather than any confirmed human measurement, and some commercial sources acknowledge that human pharmacokinetic data for andarine have never been officially published.

This matters directly for the question of dosage: any number presented online as a 'standard,' 'beginner,' or 'clinical' andarine dose is not derived from a peer-reviewed human trial. It is either extrapolated from animal studies, copied between commercial or fitness-industry websites, or based on unverified self-reports from people using an unregulated product of unknown purity.

The pattern that does exist in the animal literature is a tissue-selectivity signal rather than a dosing guideline. In castrated rat models (the Hershberger assay), andarine and a related early SARM prevented castration-induced atrophy of the levator ani muscle while acting only as weak agonists in the prostate, illustrating the anabolic/androgenic dissociation that made SARMs pharmacologically interesting in the first place. That kind of finding supports a mechanism of action; it does not translate into a validated human dose, because rodent-to-human extrapolation for a compound with no published human pharmacokinetic study is not reliable.

What Dosages Are Reported in Non-Clinical and Gray-Market Use?

Commercial SARM vendors and bodybuilding/fitness content sites commonly describe andarine being used at doses of roughly 10 mg to 100 mg per day, typically split into two or more administrations because of its reportedly short half-life. Even among these non-clinical sources, the figures are inconsistent: some vendor pages describe 100 mg per day as a 'sweet spot,' while others use that same phrase for 50 mg per day. This inconsistency between commercial sources is itself evidence of how little standardized data exists, since these figures come from self-reported or vendor-generated content rather than clinical measurement.

These same non-clinical sources report that vision-related side effects (discussed below) become more frequently reported as daily amounts increase, particularly at figures at or above 50 mg per day, and with longer periods of continuous use. These are anecdotal, uncontrolled observations, not findings from monitored clinical research.

This section describes what is reported in non-clinical and commercial sources for informational context only. It is not a recommendation to use andarine at any dose, and none of these figures should be treated as safe, effective, or medically validated, given the absence of controlled human trial data.

How Strong Is the Evidence Behind Andarine's Effects?

The evidence base for andarine is weak by clinical pharmacology standards. It consists of preclinical pharmacology, receptor-binding, and rat/dog pharmacokinetic studies, along with a small body of in vitro cancer-cell research. Separate laboratory studies have reported that andarine suppresses PI3K/AKT/mTOR signaling in human hepatocellular carcinoma cells and restricts proliferation with cell-cycle arrest in a pancreatic cancer cell line. These are early-stage, cell-culture findings; none of them establish safety or a dose-response relationship in living humans, and none support any therapeutic use outside a research setting.

By contrast, the related SARM enobosarm has published human data: Phase I and Phase II trials in healthy volunteers, elderly men, postmenopausal women, and cancer patients, with defined milligram doses (studies have evaluated single doses up to 100 mg and repeated daily doses in the range of roughly 1 mg to 30 mg), measured pharmacokinetics, and monitored lean body mass and liver-enzyme safety endpoints. The existence of this human data for a closely related compound throws the absence of equivalent published data for andarine into sharp relief.

Any claim that andarine has been 'tested in clinical settings' at bodybuilding-style doses without meaningful side effects is not supported by a findable, published, peer-reviewed human clinical trial. Readers should treat such claims, wherever encountered, as unverified marketing language rather than scientific evidence.

Side Effects Reported at Various Doses

The most distinctive reported effect associated with andarine use is a visual disturbance, commonly described by users and vendor sources as a yellow tint to vision and difficulty adjusting to darkness. This effect is widely reported as becoming more common at higher self-reported daily doses. The precise physiological mechanism has not been clearly established in the published literature, and no controlled human study has characterized its dose-response relationship or long-term reversibility with any precision; anecdotal reports describe resolution over days to weeks after stopping use, but this is not confirmed by monitored clinical follow-up.

General side effects reported for andarine, per compiled drug-information summaries, include sleep problems, fertility problems, nausea, and vision changes, with more serious reported problems including heart attack, stroke, liver damage, hallucinations, psychotic-like behavior, and sexual problems. The FDA has separately warned that SARM-containing bodybuilding products as a class have been associated with life-threatening reactions, including liver toxicity, an increased risk of heart attack and stroke, psychosis, sleep disturbances, sexual dysfunction, infertility, pregnancy miscarriage, and testicular shrinkage, and has stated that the long-term effects of these substances on the body remain unknown.

Reduced endogenous testosterone production (via suppression of luteinizing hormone and follicle-stimulating hormone) is reported by commercial and gray-market sources as a class effect of androgen receptor agonists, but controlled human hormone data specific to andarine, as opposed to anecdotal or vendor reports, do not exist.

An additional risk is product quality. Because andarine is not manufactured under pharmaceutical regulatory oversight, laboratory analyses of supplements marketed as containing SARMs, including andarine, have found that declared ingredients are sometimes absent, present in incorrect amounts, or otherwise inconsistent with labeling. The first reported adverse analytical finding for andarine in a sports drug-testing context dates to 2011, and cases of SARM misuse in sport have continued to be recorded since.

Legal Status: FDA and WADA Position

No SARM, including andarine, is approved by the FDA for any human use. The FDA has issued warning letters to companies, including Infantry Labs, IronMagLabs, and Panther Sports Nutrition, for distributing bodybuilding products containing SARMs, and has stated that such products 'have not been approved by the FDA and are associated with serious safety concerns, including potential to increase the risk of heart attack or stroke and life threatening reactions like liver damage.' The FDA has also issued a broader public health advisory warning consumers not to use body-building products represented to contain steroids or steroid-like substances.

Andarine has been included on the World Anti-Doping Agency's Prohibited List since 2008. It is currently listed by name, alongside enobosarm (ostarine), LGD-4033 (ligandrol), RAD140, S-23, and YK-11, under section S1.2, 'Other Anabolic Agents,' and SARMs in this category are prohibited at all times, both in and out of competition, for any athlete subject to the WADA Code.

Athletes and recreational users should also be aware that because gray-market SARM supply chains are not independently verified for purity or correct labeling, use of these products carries a documented risk of inadvertent exposure to undeclared or mislabeled prohibited substances.

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