Andarine (S4): What the Research Record Shows, and Why No Dosing Guidance Exists

Key takeaways

Why there is no legitimate answer to "how to take andarine"

Andarine, also known as S-4 or GTx-007, is a nonsteroidal selective androgen receptor modulator (SARM) that was developed by GTx, Inc. It has never been approved by any national regulatory agency for any human indication, and no dosing regimen for it has been validated in published, peer-reviewed human research. Andarine is not recognized as a legal dietary supplement ingredient in the United States, and products containing it are treated by regulators as unapproved drugs regardless of how they are labeled.

Because of this, any specific number of milligrams, timing schedule, or cycle length that circulates online comes from unregulated commercial sources, bodybuilding forums, or anecdotal self-experimentation rather than from controlled clinical trials with independent oversight. This page summarizes what the available scientific and regulatory record documents about andarine's development, its limited and disputed human trial history, and the risks reported in connection with its non-medical use. It does not recommend or endorse a dosing protocol.

What is actually known about andarine's clinical trial history

Andarine's pharmacology was characterized in preclinical work published by researchers associated with its development, describing tissue-selective anabolic effects on muscle and bone in castrated rodent models with reduced stimulation of androgen-sensitive tissue such as the prostate, relative to testosterone. An encyclopedic summary of the compound's regulatory history states that <cite index="8-3">Andarine is thought to have been the first SARM to enter human clinical trials.</cite>

The most specific public account of what happened in that trial program describes three completed early-phase studies rather than a single trial. According to that account, <cite index="42-1,42-2,42-3,42-4">andarine completed phase 1 clinical trials for cachexia in 2003, with three phase 1 trials (1a, 1b, 1c) completed involving 86 healthy male and female volunteers, and phase 2 trials were planned for 2004; however, development of andarine was discontinued, reportedly due to findings of visual disturbances in clinical studies.</cite> This differs from claims, common in commercial and forum sources, that attribute the discontinuation solely to a business decision to prioritize a different compound. The same historical summary notes that <cite index="8-2">development of andarine for all indications has been discontinued, in favor of the structurally related and improved compound enobosarm (ostarine; GTx-024; S-22)</cite>, so both a safety signal and a strategic pivot toward a follow-on compound appear to be part of the record.

No detailed human pharmacokinetic dataset for andarine has been published in a peer-reviewed journal. An independent, non-peer-reviewed analysis of the compound's history that examined this question directly concluded that <cite index="11-1,11-6">data showing the pharmacokinetics of S4 in humans has never been published</cite>, meaning the widely repeated claim that andarine's human elimination half-life is approximately four hours cannot be traced to any published clinical pharmacokinetic study. Any dosing frequency built around that figure, such as splitting a daily amount into multiple intakes, rests on an unverified assumption rather than confirmed human pharmacokinetics.

How andarine is reported to be sold and administered outside clinical settings

In practice, andarine is sold online as an oral liquid or capsule, frequently marketed with a "research chemical" or "not for human consumption" label. Regulators do not treat this labeling as changing the product's legal or safety status. The FDA has continued enforcement action against sellers of SARM products; in December 2025 the agency issued warning letters to multiple companies, including one letter to a firm advising it that <cite index="47-2">firm's website as selective androgen receptor modulators (SARMs) including, but not limited to, "GE Labs Ykarine" and "GE Labs MK 677"</cite>, and another warning letter identified a company marketing a product listed as <cite index="47-2">"SARM's S4 ANDARINE,"</cite> among other SARM products, for sale in the United States.

Independent chemical analyses of SARM products purchased over the internet have found substantial quality-control problems that make any stated dose on a label unreliable. A JAMA investigation that tested 44 products marketed as SARMs found that <cite index="33-14,33-15,33-16,33-17,33-18">among 44 products marketed and sold as selective androgen receptor modulators, only 23 (52%) contained one or more selective androgen receptor modulators (Ostarine, LGD-4033, or Andarine); an additional 17 products (39%) contained another unapproved drug; no active compound was detected in 4 (9%) of products; substances not listed on the label were found in 11 (25%); and in only 18 of the 44 products (41%) did the amount of active compound match the label</cite>. This means a person using a commercial andarine product cannot know, without independent laboratory testing, whether the actual content matches the label, which undermines any attempt to follow a specific dosing schedule found online.

Reported side effects, including the visual disturbances associated with andarine

The adverse effect most distinctively associated with andarine is a disturbance of vision, commonly described as a yellow or greenish tint to vision and impaired adaptation to low light. Sport Integrity Australia, an Australian government sport-integrity body, lists <cite index="34-9">eyesight, such as altered perception and colours</cite>, among the health risks associated with andarine use, and a substance-safety summary describes <cite index="43-15,43-16">reported health risks including vision impairment such as blurred or yellowish vision (especially at night), suppressed testosterone production, and possible mood effects, with the prevalence of visual side effects contributing to abandonment in clinical development</cite>. The precise retinal or ocular mechanism has not been established in controlled human research that is publicly available, so any long-term significance of repeated exposure to this effect is not established, only presumed reversible based on limited early trial reports and user accounts.

Liver injury is a broader concern that has been documented for the SARM class as a whole, though the published case reports identified in the literature involve other SARMs, chiefly ligandrol (LGD-4033) and ostarine, more often than andarine specifically. A recent review of hepatotoxicity attributed to SARMs noted that <cite index="18-6">a review of the current literature identified only a limited number of published cases of SARM-DILI</cite>, meaning the overall human case-report base for this class of drugs remains small. The NIH's LiverTox resource documents one representative case in which a young man developed <cite index="19-1">nausea, abdominal pain, and fatigue followed by itching, dark urine and jaundice</cite> after taking a five-SARM stack product that, in that instance, did not include andarine among its labeled ingredients. Other published case reports describe similar cholestatic liver injury patterns following use of ligandrol or ostarine, including cases with <cite index="22-2">cholestatic hepatitis with a mild portal, periportal, and perisinusoidal fibrosis</cite> confirmed by liver biopsy. Because commercial andarine products are frequently mislabeled or combined with other unapproved compounds, it is often not possible in real-world reports to attribute liver injury to andarine specifically rather than to a co-ingested substance.

Regulatory sources describe additional cardiovascular and safety concerns associated with SARM products generally. The FDA has stated that individuals who used SARM-containing bodybuilding products have suffered <cite index="45-6,45-7">life-threatening reactions, including liver toxicity, and that SARMs also could increase the risk of heart attack and stroke, with long-term effects on the body unknown</cite>. Animal data specific to andarine show it can affect the hypothalamic-pituitary-gonadal axis under some conditions: one summary of preclinical findings notes that <cite index="13-13,13-14">Andarine suppressed LH and FSH in castrated rats where these hormones were elevated as a result of castration, but had no effect in normal male rats</cite>, while the same source concludes that <cite index="13-15">it is unknown if and how much Andarine would suppress testosterone/estrogen production in humans</cite>. Controlled human dose-response data on this question do not exist in the published literature.

Legal status and anti-doping status

Andarine is not approved for human use anywhere and is prohibited in competitive sport. A substance-compliance summary states that <cite index="43-3,43-4">andarine has been listed on the World Anti-Doping Agency (WADA) Prohibited List since 2008 and remains banned in all athletic competition, included in section S1.2 as an "other anabolic agent," prohibited during and outside of competition</cite>. The U.S. Anti-Doping Agency similarly lists <cite index="44-1,44-2">SARMs in the category of "Other Anabolic Agents" under section S1.2 of the WADA Prohibited List, with examples including ostarine, andarine, LGD-4033 (ligandrol), and RAD140</cite>, and notes that these substances are <cite index="44-3,44-4,44-5">not approved by the FDA for human use, not drugs that a doctor can prescribe, not legal for use in compounded medicines or dietary supplements, and prohibited at all times for all athletes</cite>. Sport Integrity Australia has issued a direct public warning stating that <cite index="34-4">clinical trials on the Selective Androgen Receptor Modulator (SARM) Andarine (S4) have been discontinued and it is not approved for human use</cite>, and that agency has documented andarine detections in athletes, <cite index="34-13">with one positive test in 2016, three in 2017</cite>.

In the United States, the FDA does not recognize andarine as a legal dietary supplement ingredient, and it has continued to pursue enforcement against companies selling it as one, including warning letters issued in December 2025 to multiple sellers of SARM products, one of which explicitly named an "S4 ANDARINE" product.

What the strength of evidence actually supports

Grading the evidence honestly: preclinical (animal and cell-based) data on andarine's androgen receptor binding and tissue-selective anabolic activity are relatively substantial for a compound of this age, dating to its original pharmacodynamic characterization in the early 2000s. Evidence at the human level is thin and, on some points, contested. Historical accounts describe three completed phase 1 trials with 86 volunteers and a planned phase 2 program that did not proceed, reportedly because of visual disturbances observed in the clinical studies, but no detailed peer-reviewed report of these trials' methods, full results, or safety data has been published for independent scrutiny. There is no published human pharmacokinetic profile, no randomized controlled trial establishing an effective or safe human dose, and no long-term human safety data.

Everything described in commercial and enthusiast literature about "how to take" andarine, including specific milligram amounts, split-dosing schedules, and cycle lengths, is derived from unregulated self-experimentation and product marketing, not from clinical evidence. Independent testing of commercial SARM products has repeatedly found that labeled contents do not reliably match actual contents, which further undermines any attempt to apply a consistent dose. Given the combination of an unresolved safety signal (visual disturbances), suppressed hormone effects observed in animal models, documented liver injury associated with the broader SARM class, and unreliable product quality, the overall evidence does not support any specific route, dose, or schedule of andarine use in humans.

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