Andarine (S-4) and Hair Loss: What the Evidence Actually Shows

Key takeaways

What Is Andarine (S-4) and Why Would It Affect Hair?

Andarine, also known as S-4 or GTx-007, is a nonsteroidal selective androgen receptor modulator (SARM). <cite index="1-1">It was developed by GTx, Inc. for the treatment of conditions such as muscle wasting, osteoporosis, and benign prostatic hyperplasia, using the nonsteroidal antiandrogen bicalutamide as a lead compound.</cite> <cite index="1-2,1-3">Development of andarine for all indications has since been discontinued in favor of the structurally related and improved compound enobosarm (ostarine, GTx-024), and andarine is an orally active partial agonist of the androgen receptor.</cite> It is sold today as an unapproved research chemical and bodybuilding product.

SARMs are designed to activate the androgen receptor preferentially in muscle and bone while limiting activation in tissues such as the prostate. The rationale is best documented for the related compound enobosarm. <cite index="9-1,9-2,9-3">Enobosarm (GTx-024) is an oral nonsteroidal SARM being developed for clinical use because of its selectivity for anabolic activity with minimal androgenic activity, binds to the androgen receptor with similar affinity as testosterone, and, unlike testosterone and other steroidal androgens, cannot be aromatized to estrogenic metabolites.</cite> <cite index="9-4,9-5">The hypothesis behind this selectivity is that the nonsteroidal molecule induces slight conformational changes in the androgen receptor upon binding, altering its interaction with coactivator and corepressor proteins present in different tissues and producing a different pattern of gene activation across tissues.</cite> Andarine is believed to work through a comparable mechanism, though it is a distinct molecule with its own binding profile.

The relevance to hair is straightforward: scalp hair follicles are androgen-sensitive tissue. Any compound that activates the androgen receptor, even partially and even in a tissue-preferential way, has a plausible mechanistic route to influencing hair growth in people who are genetically predisposed to androgenetic alopecia, for the same reasons that testosterone and dihydrotestosterone (DHT) themselves do. Whether that theoretical mechanism translates into a measurable clinical effect for andarine specifically has never been tested in a controlled human study.

How Androgens Cause Hair Loss (Androgenetic Alopecia)

Androgenetic alopecia (male- and female-pattern hair loss) is driven by androgen receptor activity in the hair follicle's dermal papilla. <cite index="23-11,23-12">The major circulating androgen, testosterone, is converted to the more potent androgen dihydrotestosterone by the enzyme 5-alpha reductase, and androgen receptors and 5-alpha reductase are present in significantly higher amounts in balding scalp hair follicles than in nonbalding follicles.</cite> <cite index="21-7">Hormone-binding assays and RT-PCR studies have shown that androgen receptor expression is significantly higher in bald dermal papilla cells than in non-bald cells.</cite>

<cite index="25-2">Androgen receptor activation shortens the anagen, or growth, phase of the normal hair cycle, which drives follicular miniaturization by progressively shortening the anagen phase in androgenetic alopecia.</cite> <cite index="23-6,23-7">The basic pathology is progressive miniaturization of terminal hair follicles and their eventual conversion to fine vellus hair, as the duration of the anagen phase diminishes with each successive cycle while the telogen (resting) phase stays constant or lengthens.</cite> Over repeated cycles the hair produced becomes shorter and finer until it can no longer reach the skin surface.

Genetic susceptibility determines who is affected by any given level of androgen receptor activation. <cite index="23-13,23-14">Genetic predisposition plays a crucial role in androgenetic alopecia, and various genetic loci, including the androgen receptor gene and the ectodysplasin A2 receptor gene, have been strongly implicated.</cite> <cite index="25-5">Individuals with androgenetic alopecia exhibit elevated dihydrotestosterone production, heightened 5-alpha reductase activity, and an increased abundance of androgen receptors specifically in the areas of the scalp affected by balding.</cite> This is why exposure to an androgen or androgen receptor agonist does not produce hair loss in everyone, and why the same compound can be inert in one person and accelerate shedding in another who carries the relevant genetic predisposition.

Does Andarine Actually Cause Hair Loss? What the Human Data Show

There is no published human clinical trial data on andarine and hair loss. <cite index="55-10">Secondary sources consistently report that andarine did not undergo any published Phase I human clinical trials</cite>, with development apparently abandoned in favor of enobosarm rather than carried forward to the point where systematic safety monitoring, including dermatological or hair assessments, would have occurred. A minority of secondary sources describe andarine as having entered and then stopped in human testing, but no peer-reviewed publication or ClinicalTrials.gov record documenting completed human trials of andarine could be identified, so the more conservative and better-supported conclusion is that no verified human trial data exists for this specific compound.

The most relevant available human data comes from a 2023 systematic review of the SARM class as a whole, not andarine specifically. <cite index="30-6">That review searched PubMed, Scopus, Web of Science, and ClinicalTrials.gov and included 33 studies covering 2,136 patients, of whom 1,447 were exposed to a SARM.</cite> <cite index="30-7">The reported adverse events were 15 case reports of drug-induced liver injury, one case of Achilles tendon rupture, one case of rhabdomyolysis, and one case of mild reversible liver enzyme elevation.</cite> <cite index="30-8">Elevated alanine aminotransferase was also commonly reported across clinical trials, with a mean of 7.1%.</cite> Hair loss or alopecia was not listed among the documented adverse events in this review. This absence is not strong evidence of safety, because the review's case reports and trials were drawn almost entirely from other SARMs (ostarine, LGD-4033, RAD140, GSK2881078), and andarine contributed essentially no data of its own.

A separate review focused on SARM-associated liver injury reached similar conclusions about the overall evidence base. <cite index="35-4">A detailed breakdown of the same literature found 15 case reports of liver injury, including 8 attributed to LGD-4033, 6 to RAD140, 3 to ostarine, and 1 to YK11, with ALT elevation rates across 17 clinical trials of 13 different SARMs ranging from 0% to 63%, though most elevations were mild and reversible and none were accompanied by jaundice.</cite> Again, andarine is not named as a contributor to any of these documented cases, largely because it was never studied in the controlled settings that would generate such reports.

In the absence of controlled data, reports of hair shedding attributed to andarine circulate almost entirely as anecdote on bodybuilding forums and vendor sites, where accounts are confounded by concurrent use of other compounds, unverified product content, and pre-existing genetic pattern hair loss that may have been coincidental rather than caused. This is not the same standard of evidence as a published case report or clinical trial finding, and it should be weighed accordingly.

How Andarine Compares to Other SARMs and to Anabolic Steroids for Hair Effects

Andarine and other SARMs are frequently marketed as having fewer androgenic side effects, including hair loss, than testosterone or classic anabolic-androgenic steroids, on the basis of their designed tissue selectivity. This selectivity has a documented pharmacological rationale in preclinical work. <cite index="4-9,4-10,4-11">In one industry pharmacology study, the S-isomer of GTx-007 (andarine) showed lower potency and intrinsic activity than testosterone propionate in increasing prostate and seminal vesicle weight in castrated rats, but greater potency and intrinsic activity in increasing levator ani (muscle) weight, making it a potent nonsteroidal anabolic agent with less androgenic activity but more anabolic activity than testosterone propionate in that model.</cite> <cite index="4-13">In the same preclinical work, GTx-007 did not suppress luteinizing hormone or follicle-stimulating hormone production at the dose tested.</cite> That finding argues against assuming reflexive, uniform androgen receptor activation across every tissue at every dose, but it comes from a single rodent study at one specific dose and cannot be extrapolated to confirm an absence of hormonal suppression, or of scalp effects, in humans using higher recreational doses.

Tissue selectivity demonstrated in rodent models does not automatically transfer to confirmed selectivity for human scalp tissue, particularly since andarine was never carried through human trials where this could be verified with the kind of dermal papilla or hair-count endpoints used in androgenetic alopecia research. Claims that andarine is inherently gentler on hair than other androgenic compounds are extrapolations from preclinical pharmacology and marketing material, not confirmed clinical findings.

Reviews of the SARM class as a whole tend to discuss general safety rather than compound-specific or hair-specific data. <cite index="38-1,38-2,38-3,38-4">Selective androgen receptor modulators have demonstrated agonist activity on the androgen receptor in various tissues and stimulate muscle mass growth and bone reconstruction, but despite being studied in clinical trials, none has been approved by the Food and Drug Administration or the European Medicines Agency for pharmacotherapy, and the FDA has issued warnings about health risks while long-term exposure and the possible adverse events still need to be fully understood.</cite> This uncertainty extends to hair effects: an absence of confirmed reports in a small, short-duration evidence base is not the same as confirmed safety for hair.

Other Andarine Side Effects the Evidence Does Support

The best-documented adverse effect associated with andarine use is a reversible visual disturbance, reported consistently across independent secondary sources tracking user experience and anti-doping literature. <cite index="50-1,50-2,50-3">Adverse effects associated with andarine include vision impairment, with frequently reported symptoms of blurred vision, a yellowish shade to vision, and vision flashes, particularly noticeable at night, believed to result from the S-4 molecule binding to receptors in ocular tissue.</cite> These reports are not derived from a controlled clinical trial, since none exists for andarine, but the pattern is described consistently enough across independent sources to be treated as a genuine, if unquantified, signal rather than a fabricated claim.

More broadly, the SARM class carries documented risks that are far better established than any hair-related claim, and these come directly from the FDA. <cite index="47-16,47-17">The FDA states that life-threatening reactions, including liver injuries that required hospitalization, have occurred in people taking products containing SARMs, and that SARMs also have the potential to cause increased risk of heart attack or stroke, psychosis and hallucinations, sleep disturbances, sexual dysfunction, liver injury and acute liver failure, infertility, pregnancy miscarriage, and testicular shrinkage.</cite> <cite index="48-2,48-3">The FDA has stated plainly that the reality is SARMs are potentially dangerous, and that the agency continues to receive adverse event reports associated with their use.</cite>

Hormone suppression is a recognized concern for the SARM class in general, though the evidence specific to andarine is thin and, as noted above, one preclinical rat study found no suppression of LH or FSH at the dose tested. Whether recreational doses used by humans suppress endogenous testosterone production has not been established for andarine in any published human study; it is inferred by analogy to other SARMs and to androgens generally, not demonstrated directly.

Regulatory Status and Practical Takeaway

Andarine is not approved for human use by any regulatory authority. <cite index="47-11,47-12">The FDA states that SARMs are chemical substances that mimic the effects of testosterone and anabolic steroids, have not been approved by the FDA, and are illegally marketed as bodybuilding products.</cite> <cite index="50-10">Andarine has been listed on the World Anti-Doping Agency Prohibited List since 2008 and remains banned in all athletic competition.</cite>

Because andarine is sold as an unregulated research chemical, product purity and actual dose are not verified by any regulatory body, which further complicates any attempt to attribute a specific symptom, including hair shedding, to the labeled compound rather than to a contaminant, a mislabeled ingredient, or an entirely unrelated cause.

On the specific question of hair loss: the mechanistic plausibility is real, because andarine activates the same androgen receptor pathway implicated in androgenetic alopecia, and because genetic susceptibility, rather than the specific androgen involved, determines who is affected by that activation. However, the clinical evidence needed to confirm, quantify, or rule out this effect in humans does not exist, because andarine was never carried through human trials where such monitoring would occur. People who are already genetically predisposed to androgenetic alopecia have a plausible, biologically grounded reason for caution around any androgen receptor agonist, andarine included, but this is a statement about mechanism and risk, not a demonstrated clinical outcome specific to this compound. No SARM, including andarine, is approved for human use, and the documented harms that do exist for the class, liver injury, cardiovascular risk, and psychiatric and reproductive effects, are better established and more serious than any hair-related concern.

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