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SARMs and SERMs

SARMs are sold as steroids without the downsides. The trials and the lab tests say otherwise.

The short version

SARMs are unapproved drugs. In trials they added a little lean weight and lowered men's own testosterone. About half the products sold online did not contain what the label said. SERMs are real prescription drugs made for other uses, and the gym use of them has almost no trials behind it.

What's a SARM?

Short for selective androgen receptor modulator. A lab-made drug that flips the same switch in the body that testosterone does. None is approved by the FDA.

What's a SERM?

Short for selective estrogen receptor modulator. A prescription drug that blocks estrogen in some parts of the body. Tamoxifen and clomiphene are the best known. They were made for breast cancer and for fertility treatment in women, not for the gym.

What the trials found

B

Ostarine (enobosarm)

In a 12-week trial of 120 older adults, lean mass rose about 1.3 kg at the highest amount tested, clearly more than placebo, and stair-climbing power improved. In cancer patients, lean mass rose 1 to 1.5 kg. Two large late-stage trials then tested lean mass and stair-climbing power together. A later review says lean mass improved but function did not. It is not FDA-approved.

heavier on a scan, not clearly stronger

B

Ligandrol (LGD-4033)

One 21-day trial in 76 healthy men. Lean mass went up. Their own testosterone and their "good" HDL cholesterol went down. Both returned to normal after they stopped.

lean mass up, testosterone down

C

RAD-140

We found no human trial of it for muscle. Its first human trial was in 22 women with advanced breast cancer. The most common side effect was abnormal liver blood tests. Up to 59% of the women had them. Doctors have also published cases of liver injury in men using RAD-140 or LGD-4033 products. They recovered over about three months after stopping.

liver injury is on record

C

Cardarine (GW501516)

Sold next to SARMs, but it is not one. It works on a different target. Anti-doping agencies say its maker dropped it after animal tests showed serious harm, including cancer. The human trials we found measured blood fats, not muscle or endurance. It has turned up inside products sold as SARMs.

dropped by its own maker

B

Clomiphene and enclomiphene, in men with low testosterone

In trials they raised testosterone readings, and unlike testosterone gel they did not lower sperm counts. Neither is FDA-approved for men. One 2026 review found lower sex-drive scores than with gel.

B

Tamoxifen, for breast growth in men

The good studies are in men taking prostate cancer drugs: 9 trials in 1,573 patients found it sharply cut breast growth. That use is not on its label. The label warns of dangerous blood clots. In one large prevention trial in women, clots in the lung were three times as common on tamoxifen, 18 cases against 6.

tested in cancer patients, not lifters

Gym lore, checked

Gym lore is what people say, not what we recommend. Each one is followed by what studies in people show. Stories are real experiences. They are not proof.

"SARMs build muscle without shutting down your testosterone"

Wrong, by the trials. In the ligandrol trial, men's own testosterone fell while they took it. In the ostarine trial, total testosterone fell in men at the two highest amounts tested.

Testosterone fell in trials

"it's sold as a supplement, so it's legal and safe"

The FDA says no to both. The FDA says SARMs are not approved drugs and are not dietary supplements, even when sold as supplements. The harms it lists include heart attack or stroke, liver injury and liver failure, hallucinations, sleep problems, infertility and testicular shrinkage. A 2023 review of 33 studies counted 15 published reports of liver injury in SARM users.

FDA warning, 2023

"what's on the label is what's in the bottle"

About half the time. Researchers bought 44 products sold online as SARMs and tested them. Only 23 contained a SARM at all. 17 contained a different unapproved drug. 4 contained nothing active. The amount matched the label in just 18 of the 44.

52% contained a SARM41% matched the label

"PCT with a SERM brings your natural testosterone back"

Never tested in a proper trial. PCT means post-cycle therapy: taking a SERM after steroids or SARMs. No randomized trial has tested it. What exists is doctors looking back at records and men answering surveys. A 2026 review says most men's hormones recover by themselves within months of stopping, calls the benefit uncertain, and says it is generally not recommended.

No randomized trialRecords and surveys only

What we don't know

  • The long-term effects of any SARM. The trials ran weeks to months.
  • Whether any SARM makes people stronger or more able, not just heavier on a scan.
  • What is in any given bottle.
  • Anything about andarine (S-4), S-23, YK-11 or SR9009 in people. They are sold alongside these, and we found no human trial of any of them. YK-11 and SR9009 are not SARMs.

Sources

  1. Enobosarm in older adults, trial in 120. Journal of Cachexia, Sarcopenia and Muscle, 2011. Journal page
  2. Enobosarm in cancer patients, trial. Lancet Oncology, 2013. Journal page
  3. Enobosarm late-stage trial design. Current Oncology Reports, 2016. Journal page
  4. Review reporting the late-stage enobosarm results. Current Opinion in Supportive and Palliative Care, 2018. Journal page
  5. LGD-4033 in healthy men, trial in 76. Journals of Gerontology Series A, 2013. Journal page
  6. RAD-140 in women with breast cancer, first human trial. Clinical Breast Cancer, 2022. Journal page
  7. Liver injury with RAD-140 and LGD-4033, case report. ACG Case Reports Journal, 2020. Journal page
  8. Liver injury with LGD-4033, case report. ACG Case Reports Journal, 2020. Journal page
  9. Liver injury with SARMs, two cases. World Journal of Clinical Cases, 2021. Journal page
  10. What is in products sold as SARMs, analysis of 44. JAMA, 2017. Journal page
  11. FDA warning on SARMs, April 2023. FDA
  12. USADA on GW1516. USADA
  13. Cardarine trial in 268 adults. Arteriosclerosis, Thrombosis, and Vascular Biology, 2012. Journal page
  14. USADA on SARMs and substances sold as SARMs. USADA
  15. SARM side effects in healthy adults, review of 33 studies. Journal of Xenobiotics, 2023. Journal page
  16. WADA alert on GW501516, 2013. WADA
  17. Enclomiphene in men with low testosterone, two trials. BJU International, 2016. Journal page
  18. Clomiphene in men, review of 19 studies. Andrology, 2022. Journal page
  19. Clomiphene versus testosterone, 2026 review. European Journal of Clinical Pharmacology. Journal page
  20. Tamoxifen for breast growth in prostate cancer patients, review of 9 trials. Current Oncology, 2012. Journal page
  21. Tamoxifen label. DailyMed
  22. Recovery after steroid use, 2026 review. Endocrine Connections. Journal page
  23. Hormone recovery after steroid use, records of 641 men. European Journal of Endocrinology, 2023. Journal page

Studies found on PubMed. Last checked November 12, 2026. Information only. Not medical advice.