RESEARCH MONOGRAPH · KDC-MN-264

Andarine (S-4)

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

44/100

First-generation SARM with a real visual side effect signal and modest performance relative to successors

Andarine (S-4, also S-40503 in some early literature) is one of the earliest SARMs, developed at GTx in the early 2000s as part of the same program that produced ostarine. It was passed over for further clinical development in favor of newer candidates, partly because of efficacy considerations and partly because of an unusual visual side effect.

The signature side effect, reported across both animal work and the small human exposure data, is a yellowish tint to vision and reduced night vision adaptation. The mechanism is thought to involve binding to androgen receptors in the retina (which expresses AR at low levels) and affecting opsin function or related photoreceptor signaling. The effect is dose-dependent and reversible on discontinuation in reported cases. Nobody else in the SARM class shows this signature, which is part of why andarine got mostly abandoned for clinical development.

Mechanistically it's an AR agonist with the typical preferential muscle/bone selectivity over prostate. The receptor pharmacology is fine, the tissue selectivity is comparable to ostarine, but the overall potency is lower than newer SARMs and the side effect profile makes it less attractive as a clinical candidate.

What we like for research use is that andarine is one of the few SARMs with a documented off-target effect in non-musculoskeletal tissue, which makes it a useful probe for asking questions about AR expression and function outside the canonical target tissues. The retinal AR literature is actually scientifically interesting, even if the practical implication for the compound is this-is-why-we-developed-something-else.

What we dont like is the gray-market presence relative to the evidence base. Andarine is widely sold despite being one of the SARMs with the thinnest human data and a unique adverse effect that prospective users mostly arent warned about. Sourcing is dominated by suppliers of varying reliability, and counterfeit and adulteration concerns are at least as bad as for other SARMs in this category.

Honestly the most interesting thing about andarine at this point is what it teaches you about why tissue selectivity in the AR system isnt as clean as the early SARM marketing suggested. The retina was never on anybody's target tissue list, but androgen biology doesnt care what you wanted to selectively target.

Underdeveloped and undersold relative to its scientific interest, oversold for its modest performance profile. Honest research use is fine; consumer marketing is not.

Evidence: 35
Mechanism: 60
Reliability: 50
Safety: 40
Sourcing: 40
Value: 45
Signal: 50
Staying power: 30

Plain-language summary Intrigue 55 / 100

Andarine (S-4) is the original aryl-propionamide SARM developed at the University of Tennessee in the late 1990s, the structural ancestor that ostarine was refined from. It binds the androgen receptor with tissue-selective effects similar to ostarine, with one distinctive quirk: at higher doses it binds retinal pigments and produces a reversible yellow-green tint to vision (often described as the world looking through a yellow filter). The visual effect is dose-dependent and clears within days of stopping. It never advanced past preclinical work as a drug candidate but is sold as a research chemical. WADA-banned. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Selective androgen receptor modulator (early-generation)

An early-generation aryl propionamide SARM; the structural lineage compound from which ostarine was derived.

Abstract

Andarine (S-4, GTx-007; CAS 401900-40-1; molecular formula C19H18F3N3O6; molecular weight 441.36) is a non-steroidal aryl propionamide SARM developed by Dalton and colleagues at the University of Tennessee, the structural precursor to ostarine. The compound exhibits tissue-selective AR agonism and demonstrated efficacy in osteoporosis and BPH preclinical models. Notable for a dose-dependent visual side effect: yellow-green tint to vision at doses above approximately 50 mg, attributed to non-AR-mediated effects on retinal photoreceptors and pigments. The visual effect is reversible on discontinuation but proved clinically unacceptable for long-term development; GTx redirected development to ostarine for superior tolerability. Andarine retains research utility as the prototype aryl propionamide SARM and is widely used recreationally despite no regulatory approval. Plasma half-life is approximately 4 hours.

Mechanism of action

Non-steroidal aryl propionamide SARM; tissue-selective AR agonism. Reversible yellow-tint visual side effect at supratherapeutic doses.

Reported research dose ranges

Recreational use commonly 25 to 75 mg; trial-relevant pharmacology at 3 to 30 mg/kg in animals.

References

Gao W, et al. Pharmacokinetics and pharmacodynamics of nonsteroidal androgen receptor ligands. Pharm Res 2006.
Kearbey JL, et al. Selective androgen receptor modulator (SARM) treatment prevents bone loss and reduces body fat in ovariectomized rats. Pharm Res 2007.
Dalton JT, et al. Discovery of nonsteroidal androgens. Biochem Biophys Res Commun 1998.

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KDC-MN-264

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

Kodiac sells research compounds for investigative use only.

Andarine (S-4)

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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