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S233.0

S-23 Research

Mostly mechanism / observationalLimited safety

5 peer-reviewed studies

What the evidence says

Mostly mechanism / observational

Most S-23 studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.

Most evidence is from mixed-quality studies published 2009–2025.

Based on 5 studies

Confidence

Low confidence

By outcome

Androgen & hormonal axis
Mostly mechanism / observational4 studies
Safety profile
Mostly mechanism / observational3 studies
Body composition (rats only)Increased lean mass and bone in rats; no human efficacy or safety data, with marked HPTA/fertility suppression. · Not established (no human trials)
Too few graded studies1 study
Fertility suppression (contraceptive effect)
Too few graded studies1 study

Active research area

4 studies in the last 5 years

200920172025

1Spermatogenesis suppression and body compositionAnimalCited 46×2009

In plain English: This is the first study to show that a selective androgen receptor modulator combined with EB is an effective and reversible regimen for hormonal male contraception in rats.

Jones A, Chen J, Hwang DJ, Miller DD, Dalton JT · Endocrinology (2009)

Foundational S-23 paper — high androgen-receptor binding affinity (Ki ~1.7 nM) and full-agonist activity in vitro
In intact male rats, suppressed LH (>50%) and, with estradiol benzoate, suppressed FSH and spermatogenesis: four of six rats had no sperm and zero pregnancies in mating trials
Increased bone mineral density and lean mass and reduced fat mass dose-dependently — the basis for its grey-market body-composition use

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2Label accuracy of SARM-marketed supplementsIn VitroCited 27×2021

In plain English: This study found discrepancies ranging from a supplement in which no active ingredients were found, to supplements containing undeclared prohibited analytes.

Leaney AE, Beck P, Biddle S, Brown P, Grace PB, Hudson SC, Mawson DH · Drug testing and analysis (2021)

Purchased and chemically analyzed consumer products marketed as SARMs (the grey market S-23 is sold in)
Found pervasive mislabeling — products with no active ingredient, undeclared prohibited analytes, and doses differing from the label
No SARM has met the safety/efficacy bar for FDA or EMA approval; products are illegally marketed as supplements

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3ReviewCited 14×2023

In plain English: It is shown that SARMs may increase the risk of cardiovascular diseases ... There is a noticeable lack of clinical trials and literature on the relationship between SARMs, cardiovascular diseases, and the AR.

Hall E, Vrolijk MF · Nutrients (2023)

Review of androgen-receptor pharmacology and the cardiovascular risk of abusing SARM-containing supplements
Notes SARM abuse may raise cardiovascular risk via the renin-angiotensin system, lipid profile, inflammation, platelet activity, and other pathways
Emphasizes the near-total absence of clinical trials on SARMs and cardiovascular outcomes

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4Urinary detection window of S-23In VitroCited 5×2022

In plain English: To the best of the authors knowledge, this seems to be the first study ever achieved on S-23 [in humans] ... nothing has been published about long-term effects of S-23.

Ameline A, Gheddar L, Raul JS, Kintz P · Journal of pharmaceutical and biomedical analysis (2022)

Single ~8 mg oral dose of S-23 in one human volunteer, used to characterize urinary metabolites for anti-doping — a detection study, not an efficacy or safety study
S-23 was detectable in urine from 2 h up to 28 days post-administration
Explicitly notes very few data exist and nothing is published on the long-term effects of S-23

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5Urinary elimination profile of microdosed S-23ObservationalCited 1×2025

In plain English: Among these, S-23 has been identified in five AAFs reported in 2022 ... inadvertent exposure through contaminated dietary supplements has emerged as a significant concern.

Alhalabi H, Korsmeier L, Thomas A, Thevis M · Biomedical chromatography : BMC (2025)

Microdose (1, 10, 50 µg) human administration study characterizing S-23 urinary elimination for doping control
S-23 was responsible for five adverse analytical findings (positive doping tests) in athletes in 2022
Highlights contaminated dietary supplements as a route of inadvertent S-23 exposure

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View in Research Library

S-23 Research

Mostly mechanism / observational

Preclinical characterization of a (S)-N-(4-cyano-3-trifluoromethyl-phenyl)-3-(3-fluoro, 4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide: a selective androgen receptor modulator for hormonal male contraception.

Analysis of supplements available to UK consumers purporting to contain selective androgen receptor modulators.

Androgen Receptor and Cardiovascular Disease: A Potential Risk for the Abuse of Supplements Containing Selective Androgen Receptor Modulators.

In vitro characterization of S-23 metabolites produced by human liver microsomes, and subsequent application to urine after a controlled oral administration.

Investigations Into the Urinary Metabolite Elimination Profile of the Selective Androgen Receptor Modulator S-23 in Studies Mimicking Contaminated Product Ingestion for Doping Control Purposes.