Andarine, also called S-4 or GTx-007, is an experimental nonsteroidal selective androgen receptor modulator (SARM). It was made in the early 2000s by academic groups at the Ohio State University and the University of Tennessee as one of the first SARMs to show tissue-selective effects in animals: it built muscle and bone in castrated rats while stimulating the prostate much less than testosterone-type steroids.

The single most important fact is that andarine has never been approved as a medicine anywhere, and no controlled human trial of it has been published. Everything known about its effects comes from rats, dogs and cell studies. What is known about people comes from anti-doping laboratories, analyses of black-market products and a few adverse-event reports. SARMs have been banned in sport since 2008, and the current anti-doping list names andarine.

This page summarizes what the animal studies, anti-doping research and product analyses report. It is for education only and is not medical advice.

Property	Detail
Drug class	Nonsteroidal SARM (aryl-propionamide type)
Other names	S-4, GTx-007
Formula and weight	C₁₉H₁₈F₃N₃O₆, 441.4 g/mol
Approval status	Never approved; no published controlled human trials
Routes studied	Oral and intravenous (kinetic studies in rats and dogs); subcutaneous injection in rat efficacy studies
Half-life	Animal data only: 2.6–5.3 h in rats, ≈3.3 h in dogs; no human data
Aromatization	Not a substrate for aromatase, so it is not converted to estrogen
US status	Not FDA approved; not listed as a Schedule III anabolic steroid
WADA status	Prohibited at all times, named in class S1.2 (other anabolic agents)

What it is

Andarine’s chemical name is (2S)-3-(4-acetamidophenoxy)-2-hydroxy-2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]propanamide (PubChem). It is not a steroid. It belongs to the aryl-propionamide family of SARMs, the same chemical family as ostarine (enobosarm) and S-23. In one mouse study the two compounds were labeled with the codes GTx-007 (andarine) and GTx-024 (enobosarm) (Simitsidellis et al., J Endocrinol 2019).

A SARM binds the androgen receptor, the same receptor that testosterone and DHT act on. The goal of SARM design is to activate that receptor fully in muscle and bone while activating it only partly in the prostate and other “androgenic” tissues. The rat studies that introduced andarine described exactly that pattern:

Receptor binding. The first paper tested four SARMs, which bound the androgen receptor with Ki values (a measure of binding strength; lower is stronger) of 4–37 nM (Yin et al., JPET 2003).
Tissue selectivity. In castrated rats, andarine kept the levator ani muscle (a standard rat measure of anabolic effect) at least as well as testosterone propionate, while having less effect on the prostate and seminal vesicles.
No estrogen route. Andarine does not cross-react with other steroid receptors and is not a substrate for aromatase, the enzyme that turns testosterone into estradiol (Kearbey et al., Pharm Res 2007).
No 5α-reductase effect. It only weakly inhibited human 5α-reductase types I and II in vitro (Ki over 20 µM), so it does not act like finasteride (Gao et al., Endocrinology 2004).

The structure has an aromatic nitro group (Ar–NO₂). A 2024 review flagged this group as a structural “toxicophore” that could add to toxicity risk, though this is a chemical argument, not a clinical finding (Leciejewska et al., Eur J Clin Pharmacol 2024).

Pharmacokinetics (animal data only)

No human pharmacokinetic study of andarine has been published. The available data come from rats and dogs:

Measure	Rats	Dogs
Doses tested	0.5–30 mg/kg IV; 1–30 mg/kg oral	Pharmacologically relevant IV and oral doses
Half-life	2.6–5.3 h across doses	≈200 min (≈3.3 h)
Oral bioavailability	Complete at lower doses; falls at higher doses	91% at pharmacologically relevant doses
Clearance	1.0–2.1 mL/min/kg (dose-dependent)	4.6 mL/min/kg
Main metabolism	Amide hydrolysis and nitro reduction	Deacetylation and nitro reduction
Source	Kearbey et al., Xenobiotica 2004; metabolism from Perera 2006	Perera et al., Drug Metab Dispos 2006

Metabolism differs sharply between species. In dogs, more than 50% of an IV dose was deacetylated to a metabolite called M1. In rats, and in human liver cytosol in the test tube, the enzyme N-acetyltransferase (NAT) converted M1 back into andarine. The authors warned that common inherited differences in NAT activity could cause drug interactions, and that animal data might not predict how people handle the drug (Gao et al., Drug Metab Dispos 2006).

In human urine, anti-doping labs detect andarine through several metabolites: glucuronide conjugates of the parent drug, a hydroxylated and/or deacetylated form, a product formed by removing one ring, and sulfate conjugates (Thevis et al., Rapid Commun Mass Spectrom 2010).

Regulatory status

No approval. Andarine has never been approved by the FDA or any other drug regulator. A 2009 analysis described it as a “non-approved drug candidate” being sold online (Thevis et al., Drug Test Anal 2009), and the 2017 JAMA analysis of internet SARM products described SARMs as not FDA approved (Van Wagoner et al., JAMA 2017).
Not on the DEA’s anabolic steroid list. Andarine is not among the substances named in the federal Schedule III list (21 CFR 1308.13). Its legal status as a product sold for human use is a separate question: it is not an approved drug.
Banned in sport. The WADA list names andarine under S1.2 “other anabolic agents,” prohibited both in and out of competition and classed as a non-specified substance (WADA 2026 Prohibited List). SARMs have been on the list since 2008.

What the research shows

All efficacy data below are from rats or mice. Doses are in mg/kg of animal body weight and given by injection, and they cannot be converted into human doses.

Muscle and body composition in castrated male rats

The key study let rats lose muscle and bone for 12 weeks after castration, then treated them for 8 weeks with daily injections of andarine (3 or 10 mg/kg), DHT (3 mg/kg) or vehicle, with 7–8 rats per group (Gao et al., Endocrinology 2005):

Measure	Castrated + vehicle	Andarine 3 mg/kg	Andarine 10 mg/kg	DHT 3 mg/kg	Intact controls
Soleus peak tetanic force (N)	0.57	0.86	1.02	0.95	0.85
Force per muscle area (kN/m²)	83	120	156	138	124

The study’s other main findings:

Muscle and lean mass. Both andarine doses restored soleus strength, levator ani mass and lean body mass to intact levels, similar to DHT.
Prostate. DHT drove prostate and seminal vesicle weights to more than twice normal. Andarine 3 mg/kg brought them back to only 16% and 17% of normal.
Bone. Andarine increased total-body bone mineral density significantly more than DHT.

Bone and fat in female rats

In a study of 120 female rats, most of them ovariectomized (a model of postmenopause), daily andarine injections for 120 days dose-dependently reduced body fat. The highest dose returned fat mass to the level of intact rats, and doses above 0.1 mg/day partly or fully prevented bone loss (Kearbey et al., Pharm Res 2007):

Group (120 days)	Body fat	Whole-body BMD (g/cm²)
Intact controls	28.0%	0.215
Ovariectomized + vehicle	41.0%	0.197
Ovariectomized + andarine 0.5 mg/day	33.7%	0.212
Ovariectomized + andarine 3 mg/day	29.5%	0.210

Giving the androgen-receptor blocker bicalutamide alongside andarine prevented the fat reduction and partly blocked the bone effect, showing that both ran through the androgen receptor. In a later model, where treatment started 90 days after ovary removal in aged rats, andarine restored whole-body and lumbar spine density and increased femur strength (Kearbey et al., Pharm Res 2009).

Uterus in female mice

In ovariectomized mice treated for 7 days, enobosarm, danazol and DHT all increased uterine weight and endometrial growth. Andarine had no effect on these measures (Simitsidellis et al., J Endocrinol 2019).

Humans

No randomized or controlled human study of andarine has been published. A 2023 systematic review of SARM safety in healthy adults searched specifically for andarine and included 33 studies and case reports, none of which reported andarine use (Vignali et al., J Xenobiot 2023). A 2024 pharmacovigilance review states that andarine did not advance to phase I trials (Leciejewska et al., Eur J Clin Pharmacol 2024).

Side effects and risks

With no human trials, there are no measured rates of side effects. The concerns below come from animal pharmacology, from the SARM class and from case reports.

Hormonal suppression

About the “doesn’t shut you down” claim. Andarine is often promoted as not suppressing natural testosterone. The evidence behind that comes only from castrated rats, which have no testes and very high LH. In short studies, doses near the effective dose did not significantly lower LH or FSH (Yin et al., JPET 2003). Over 8 weeks, however, andarine lowered LH and FSH in a dose-dependent way, which shows it acts on the pituitary and hypothalamus like other androgens (Gao et al., Endocrinology 2005). LH and FSH are the pituitary signals that drive the testes to make testosterone and sperm. No study has measured this in people, so whether it suppresses human testosterone is unknown.

Vision

About vision changes. Online sources often say andarine causes a yellow tint or trouble seeing in the dark. We could not trace this to any published clinical study or andarine-specific case report, so it can be neither confirmed nor ruled out. A review of FDA adverse-event reports for SARM products as a group listed “blindness or a visual impairment” among the reported events, but did not tie them to andarine (Leciejewska et al., Eur J Clin Pharmacol 2024).

Liver and other reported events

Liver injury is the best-documented risk of the SARM class. The 2023 systematic review counted 15 case reports of drug-induced liver injury with SARMs, and found raised ALT (a liver enzyme) in a mean of 7.1% of SARM-treated trial participants. None of those cases or trials reported andarine use (Vignali et al., J Xenobiot 2023).

For andarine specifically, the FDA’s CAERS database held 3 reports found by searching “andarine” and “S-4” (Leciejewska et al., Eur J Clin Pharmacol 2024):

dizziness and near-fainting (2017);
acute liver failure with hospitalization (2018);
a cardiac death (2019).

These are unverified spontaneous reports. They do not prove that andarine caused the events, and the product contents were not confirmed.

One published case describes a 47-year-old bodybuilder who developed severe new-onset diabetes after 3 months of taking andarine together with RAD-140 and ibutamoren. The authors suggested the three drugs together may have contributed, in a man already at metabolic risk (Sotorník et al., Clin Diabetes 2022). Because several drugs were involved, the case cannot be attributed to andarine.

Who should not use it

As an unapproved compound with no human safety data, andarine has no established safe dose for anyone. Competitive athletes face an anti-doping violation: labs have reported andarine in doping control samples since at least 2010 (Grata et al., Forensic Sci Int 2011).

Quality and contamination

Products sold as andarine often do not contain what the label says:

2009: The first proof that SARMs were being sold for misuse came from an andarine product bought online. It was an oily liquid labeled as green tea extract and face moisturizer. It contained andarine at ≈150 mg/mL, plus a synthesis impurity at about 10% of the andarine content (Thevis et al., Drug Test Anal 2009).
2017: Of 44 internet products sold as SARMs, only 52% contained any SARM (ostarine, LGD-4033 or andarine). Another 39% contained a different unapproved drug, and 59% had amounts that differed substantially from the label (Van Wagoner et al., JAMA 2017).
2024: Italy’s national health institute (ISS) tested 13 products bought online. One sold as andarine 15 mg per capsule contained no andarine. Instead it had ≈2 mg per capsule of cardarine plus testosterone. A second andarine product did contain andarine but was contaminated with cardarine (Gaudiano et al., Sex Med 2024).
2025: In a 5-year study of 324 samples reported by 14 official medicines control laboratories in 13 countries, andarine was among the five most common molecules found in illegal SARM-type products (Barrios et al., Drug Test Anal 2025).

Key takeaways

An early experimental SARM. Andarine (S-4, GTx-007) is a nonsteroidal androgen receptor modulator from the same chemical family as ostarine. It is not aromatized to estrogen.
No human trials. It has never been approved, and no controlled human study has been published. Its reputation rests on rat and dog data.
Strong but animal-only effects. In castrated rats it restored muscle strength, lean mass and bone similar to DHT, with much less prostate growth. In female rats it reduced fat and prevented bone loss.
Short half-life in animals. About 2.6–5.3 hours in rats and 3.3 hours in dogs. Human values are unknown, and the authors warned that metabolism differs by species.
Not hormonally neutral. It lowered LH and FSH in rats over 8 weeks. The popular vision claims cannot be confirmed from published data.
Unreliable products and banned in sport. Products sold as andarine have contained other drugs or none at all, and WADA prohibits it at all times.

Sources

Yin D, Gao W, Kearbey JD, et al. Pharmacodynamics of selective androgen receptor modulators. J Pharmacol Exp Ther. 2003;304(3):1334–1340. PubMed.
Gao W, Kearbey JD, Nair VA, et al. Comparison of the pharmacological effects of a novel selective androgen receptor modulator, the 5alpha-reductase inhibitor finasteride, and the antiandrogen hydroxyflutamide in intact rats: new approach for benign prostate hyperplasia. Endocrinology. 2004;145(12):5420–5428. PubMed.
Kearbey JD, Wu D, Gao W, et al. Pharmacokinetics of S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamide in rats, a non-steroidal selective androgen receptor modulator. Xenobiotica. 2004;34(3):273–280. PubMed.
Gao W, Reiser PJ, Coss CC, et al. Selective androgen receptor modulator treatment improves muscle strength and body composition and prevents bone loss in orchidectomized rats. Endocrinology. 2005;146(11):4887–4897. PubMed.
Gao W, Johnston JS, Miller DD, Dalton JT. Interspecies differences in pharmacokinetics and metabolism of S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethylphenyl)-propionamide: the role of N-acetyltransferase. Drug Metab Dispos. 2006;34(2):254–260. PubMed.
Perera MA, Yin D, Wu D, et al. In vivo metabolism and final disposition of a novel nonsteroidal androgen in rats and dogs. Drug Metab Dispos. 2006;34(10):1713–1721. PubMed.
Kearbey JD, Gao W, Narayanan R, et al. Selective Androgen Receptor Modulator (SARM) treatment prevents bone loss and reduces body fat in ovariectomized rats. Pharm Res. 2007;24(2):328–335. PubMed.
Kearbey JD, Gao W, Fisher SJ, et al. Effects of selective androgen receptor modulator (SARM) treatment in osteopenic female rats. Pharm Res. 2009;26(11):2471–2477. PubMed.
Simitsidellis I, Esnal-Zuffiaure A, Kelepouri O, et al. Selective androgen receptor modulators (SARMs) have specific impacts on the mouse uterus. J Endocrinol. 2019;242(3):227–239. PubMed.
Thevis M, Geyer H, Kamber M, Schänzer W. Detection of the arylpropionamide-derived selective androgen receptor modulator (SARM) S-4 (Andarine) in a black-market product. Drug Test Anal. 2009;1(8):387–392. PubMed.
Thevis M, Thomas A, Fusshöller G, et al. Mass spectrometric characterization of urinary metabolites of the selective androgen receptor modulator andarine (S-4) for routine doping control purposes. Rapid Commun Mass Spectrom. 2010;24(15):2245–2254. PubMed.
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Van Wagoner RM, Eichner A, Bhasin S, et al. Chemical composition and labeling of substances marketed as selective androgen receptor modulators and sold via the internet. JAMA. 2017;318(20):2004–2010. PubMed.
Sotorník R, Suissa R, Ardilouze JL. Could overt diabetes be triggered by abuse of selective androgen receptor modulators and growth hormone secretagogues? A case report and review of the literature. Clin Diabetes. 2022;40(3):373–379. PubMed.
Vignali JD, Pak KC, Beverley HR, et al. Systematic review of safety of selective androgen receptor modulators in healthy adults: implications for recreational users. J Xenobiot. 2023;13(2):218–236. PubMed.
Leciejewska N, Jędrejko K, Gómez-Renaud VM, et al. Selective androgen receptor modulator use and related adverse events including drug-induced liver injury: analysis of suspected cases. Eur J Clin Pharmacol. 2024;80(2):185–202. PubMed.
Gaudiano MC, Aureli F, Manna L, et al. Illegal products containing selective androgen receptor modulators purchased online from Italy: health risks for consumers. Sex Med. 2024;12(2):qfae018. PubMed.
Barrios MM, Deconinck E, Vanhee C, et al. SARMs, metabolic modulators and growth hormone secretagogues in suspected illegal medicines, bought as sport performance enhancers: a retro- and prospective study within the GEON. Drug Test Anal. 2025;17(10):2078–2085. PubMed.
National Center for Biotechnology Information. PubChem Compound Summary for CID 9824562, Andarine. PubChem.
World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA.
Code of Federal Regulations. 21 CFR 1308.13, Schedule III. eCFR.

Andarine (S4)