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SARMs Meaning: What Selective Androgen Receptor Modulators Are and Why the Term Is Used

SARMs stands for "selective androgen receptor modulators," a class of synthetic, nonsteroidal compounds designed to bind androgen receptors with tissue-selective effects on muscle and bone, none of which is approved by the FDA for human use.

SUMMARY

Key takeaways

SARM stands for selective androgen receptor modulator, a class of synthetic, nonsteroidal compounds designed to bind the androgen receptor with tissue-selective effects on muscle and bone, as described by the NCBI LiverTox database.
No SARM is approved by the FDA for human use as a drug or dietary supplement; the agency states these products are unapproved drugs that have not been reviewed for safety and effectiveness, even when marketed as dietary supplements or "research chemicals."
Enobosarm (ostarine) has the deepest clinical trial record of any SARM but its pivotal phase 3 POWER trials in cancer-related muscle wasting failed to meet their co-primary endpoints for lean mass and physical function.
Peer-reviewed case reports describe cholestatic drug-induced liver injury linked to individual SARMs, including LGD-4033, RAD140, and enobosarm, generally reversible after the product is stopped, though the evidence base consists of case reports rather than large controlled trials.
A JAMA-published chemical analysis of 44 online SARM products found that only about half contained the SARM listed on the label, and a substantial share contained other unapproved substances or no active ingredient at all.
The World Anti-Doping Agency lists SARMs, including andarine, ostarine, LGD-4033, RAD140, S-23, and YK-11, as prohibited anabolic agents at all times, and USADA warns that SARM ingredients can appear on supplement labels under alternative names.
01

What SARM Stands For

SARM is an acronym for selective androgen receptor modulator. The NCBI Bookshelf LiverTox database describes SARMs as a group of orally available, synthetic, nonsteroidal drugs that bind androgen receptors with tissue-selective activity that preserves anabolic actions on muscle and bone, but with fewer and milder androgenic effects on organs such as the prostate, skin, hair, liver, and heart. The same source notes that several such agents were developed and evaluated as therapy for cancer cachexia, osteoporosis, and age-related bone and muscle wasting, but that none has been approved for human use.

The term distinguishes these molecules from anabolic-androgenic steroids, which share the same steroid ring structure as testosterone. Because SARMs are nonsteroidal, they are structurally different from testosterone and its derivatives even though they are designed to act on the same androgen receptor.

02

Ostarine, LGD-4033, RAD140: Are All SARMs the Same?

Several distinct molecules are grouped under the SARM label, and they are not interchangeable in terms of chemical structure, evidence base, or degree of study. Enobosarm (ostarine, GTx-024, MK-2866) has one of the longest clinical development histories of any SARM, having been studied in phase 1 and phase 2 trials and then in the pivotal phase 3 POWER 1 and POWER 2 trials, two identically designed randomized, double-blind, placebo-controlled trials that assessed enobosarm's effect on lean body mass and physical function in patients with non-small-cell lung cancer starting chemotherapy. Both POWER trials failed to meet their co-primary endpoints of improvement in lean body mass and physical function, despite earlier phase 2 signals of benefit. Enobosarm has more recently been studied in a placebo-controlled phase 2b trial in combination with a GLP-1 receptor agonist for body composition in older adults with obesity; the developer has reported meeting the trial's primary endpoint in a topline company announcement, but independent peer-reviewed publication of these results was not identified in this review.

LGD-4033 (ligandrol) has undergone early-phase human study but has substantially less late-stage clinical trial data than enobosarm. It is also one of the SARMs most frequently implicated in published cases of drug-induced liver injury, including reports of severe cholestatic hepatitis confirmed by liver biopsy in a previously healthy man who had taken the compound for about two weeks, and a separate case of jaundice and elevated liver enzymes after three months of use.

RAD140 (testolone) is described in case-report literature as a novel SARM with very limited data available on its adverse-effect profile, despite being readily accessible on the consumer market. Multiple case reports describe cholestatic drug-induced liver injury in people who used RAD140 as an over-the-counter bodybuilding product, including cases with markedly elevated bilirubin that resolved after the product was stopped. One case-report author group concluded that RAD140 and other SARMs should be used with caution and under close clinical supervision until further hepatic safety data become available, given their potential hepatotoxicity and ready availability on the consumer market.

Andarine (S-4) is another nonsteroidal compound marketed as a SARM. It appears among the compounds analyzed in a 2017 JAMA study of SARM products purchased online, which found that only 23 of 44 products (52%) contained a labeled SARM ingredient such as ostarine, ligandrol, or andarine, often not in the amount stated on the label, while other products contained different unapproved drugs or, in a few cases, no active ingredient at all.

None of these compounds is FDA-approved, and the depth of human safety data differs considerably between them. Enobosarm has the most extensive trial record of any SARM, having progressed through phase 3 testing, whereas RAD140, LGD-4033, and other compounds sold under "research chemical" labeling have comparatively little controlled human data and rely mainly on case reports and small early-phase studies for their safety picture.

FAQ

Frequently asked

Is a SARM the same thing as a steroid?
No. The NCBI LiverTox database describes SARMs as synthetic, nonsteroidal drugs, meaning they lack the steroid ring structure of testosterone and anabolic-androgenic steroids, even though they are designed to bind the same androgen receptor. LiverTox describes them as having fewer and milder androgenic effects on tissues such as the prostate, skin, hair, liver, and heart compared with steroidal androgens, but this reflects their design intent as reported in the literature rather than a guarantee of safety, since case reports document significant liver injury with several SARMs.
Are SARMs legal to buy?
SARM-containing products are widely sold online, often labeled as dietary supplements or as "research chemicals not for human consumption." The FDA states that although these products are often marketed as dietary supplements, they do not meet that definition and cannot legally be marketed in the United States as a dietary supplement or a drug. The FDA has issued numerous warning letters to companies selling SARMs and has pursued criminal actions against distributors.
Do SARMs cause liver damage?
Multiple peer-reviewed case reports describe cholestatic drug-induced liver injury, including jaundice, pruritus, and markedly elevated bilirubin and liver enzymes, in people who used SARMs such as LGD-4033, RAD140, and enobosarm. Liver injury has generally resolved after the product was discontinued in these reports. The evidence consists of individual case reports rather than large controlled trials, and one review of RAD140 cases concluded that SARMs should be used cautiously and under close clinical supervision until further hepatic safety data become available.
Are SARMs banned in sports?
Yes. The World Anti-Doping Agency's Prohibited List includes SARMs, naming andarine, enobosarm (ostarine), LGD-4033 (ligandrol), RAD140, S-23, and YK-11 as examples under its Other Anabolic Agents category, prohibited at all times, both in and out of competition. USADA confirms that SARM ingredients are illegal to market as dietary supplements and warns that they can appear on product labels under various names.
Has any SARM ever been approved as a medicine?
No. Enobosarm, the most studied SARM, progressed through phase 1, phase 2, and pivotal phase 3 human trials for prevention and treatment of cancer-related muscle wasting, but the phase 3 POWER trials did not meet their co-primary endpoints for lean body mass and physical function. No SARM has received FDA approval for any indication, and the FDA classifies all SARM-containing products sold to consumers as unapproved drugs.
REF

References

  1. Selective Androgen Receptor Modulators - LiverToxNCBI Bookshelf / LiverTox
  2. Bodybuilding Products: SARMs Cause HarmU.S. Food and Drug Administration
  3. Study Design and Rationale for the Phase 3 Clinical Development Program of Enobosarm... (POWER Trials)PMC / Current Oncology Reports
  4. Enobosarm - an overviewScienceDirect Topics
  5. Ligandrol (LGD-4033)-Induced Liver InjuryPubMed / ACG Case Reports Journal
  6. LGD-4033 and a Case of Drug-Induced Liver InjuryPMC / Cureus
  7. RAD-140 Drug-Induced Liver InjuryPMC / Ochsner Journal
  8. Idiosyncratic drug-induced liver injury related to use of novel selective androgen receptor modulator RAD140 (Testalone): a case reportPMC / Journal of Medical Case Reports
  9. Severe liver injury following use of RAD-140, a selective androgen receptor modulator, for body buildingAustralian Prescriber
  10. Selective Androgen Receptor Modulators Leading to Liver Injury: A Case ReportPMC
  11. SARMs sold online often contain unapproved drugs, study saysCNN, reporting on JAMA study
  12. The Prohibited ListWorld Anti-Doping Agency
  13. Selective Androgen Receptor Modulators (SARMs)U.S. Anti-Doping Agency (USADA)
  14. Verus enobosarm meets primary endpoint in Phase 2b weight reduction trialTipRanks (company topline results)
  15. Selective Androgen Receptor Modulators (SARMs)Council for Responsible Nutrition, citing FDA statement
SARMS Institute Research Desk. Compiled from primary sources. Last updated 20 July 2026.
This page is for education and does not provide medical or legal advice. No SARM is approved for human use.