Short answer: there is no safe SARM, but there are better-known and less-known ones. No SARM is approved anywhere, and the longest trials lasted months. If “safest” means the most human research and the fewest serious warning signs at the doses tested, ostarine comes first: it has Phase 2 and Phase 3 trials in over 1,000 people. Even ostarine lowered testosterone and HDL cholesterol and has case reports of serious liver injury. Most other SARMs sold today have never been tested in a human trial at all, so their safety is not low or high, it is unknown.
Every SARM, ranked by how much is known
| Compound | Human studies | Evidence | Suppression | Liver risk | Main safety signal |
|---|---|---|---|---|---|
| Ostarine | 8 | 3/3 | 2/3 | 2/3 | Lower testosterone and HDL; liver injury case reports |
| LGD-4033 | 2 | 2/3 | 3/3 | 2/3 | Suppression at 1 mg/day; lower HDL; biopsy-confirmed liver injury cases |
| RAD-140 | 1 | 1/3 | 2/3 | 3/3 | Liver-enzyme rises in about half of trial patients; liver and heart case reports |
| Andarine (S4) | 0 | 0/3 | 2/3 | n/e | No human trials; FDA adverse event reports; vision changes reported by users |
| S-23 | 0 | 0/3 | 2/3 | n/e | No human trials; stopped sperm production in rats |
| YK-11 | 0 | 0/3 | n/e | n/e | No human trials; FDA warning after a stroke with a YK-11 product |
| RAD-150 | 0 | 0/3 | n/e | n/e | No studies of any kind |
| AC-262 | 0 | 0/3 | 2/3 | n/e | One 2-week rat study |
| ACP-105 | 0 | 0/3 | n/e | n/e | Rat and mouse studies only |
Scores run from 0 (none) to 3 (high); n/e means not established. How we score is explained in our methodology, and every number links to its study in the SARMs database.
Source: Sarmguide compound database.
1. Ostarine: the most studied
Ostarine (enobosarm) has been tested in older adults, cancer patients and, since 2024, older adults on Wegovy. At 1–3 mg/day for 86 days, it added about 1.3 kg of lean mass vs placebo, lowered total testosterone by 6–7 nmol/L and lowered HDL by 17–27%; free testosterone, LH and FSH did not change significantly. A Phase 1 study found dose-dependent ALT rises, and several case reports describe cholestatic liver injury with ostarine products. It is the best-characterised SARM, which is not the same as safe.
2. LGD-4033: well studied, strongly suppressive
LGD-4033 has two placebo-controlled trials. In healthy young men, even 1 mg/day for 21 days lowered total and free testosterone, SHBG, FSH and HDL; all were back to baseline by day 56. Several biopsy-confirmed cases of cholestatic liver injury are linked to ligandrol products. Its suppression score is the highest in our database.
3. RAD-140: one trial, clear liver signal
RAD-140’s only human trial was in 22 women with advanced breast cancer, where AST rose in 59% and ALT in 45% of patients, with serious rises in 23%. Case reports describe liver injury, heart-muscle inflammation and heart failure. It has the highest liver-risk score in the database.
The SARMs with no human data
S4 (andarine), S-23, YK-11, RAD-150, AC-262 and ACP-105 have never been tested in a human trial. What is known comes from cells, rats and dogs, plus case reports and FDA adverse event reports. Two examples: the FDA warned consumers about a product labeled as containing YK-11 after a user had a stroke (it also contained an undeclared steroid), and in rats S-23 stopped sperm production. “Mild” reputations for any of these come from forums, not studies.
The non-SARMs often sold as “safe” alternatives
| Compound | Human studies | Evidence | Suppression | Liver risk | Main safety signal |
|---|---|---|---|---|---|
| MK-677 | 17 | 3/3 | 1/3 | 1/3 | Hunger, water retention, higher blood sugar; heart-failure signal in frail older adults |
| Cardarine | 4 | 2/3 | 0/3 | 1/3 | Cancers in 2-year rat and mouse studies; development stopped |
| SR9009 | 0 | 0/3 | n/e | 2/3 | Never tested in people; liver failure case needing a transplant |
MK-677 has the most human data of any compound here (17 trials), but its side effects are well documented. Cardarine and SR9009 are often called “safe” because they do not suppress testosterone; cardarine caused cancers in long-term animal studies, and SR9009 has never been tested in people and has a case of liver failure needing a transplant.
Is there a safe SARM for beginners?
No. Beginners are often steered to ostarine because it has the most data and partial rather than full suppression in trials, but it still lowered testosterone and HDL at 1–3 mg/day and has serious liver case reports. Products are another risk: in a 2017 test of 44 SARM products bought online, only 52% contained a SARM and 39% contained another unapproved drug. If you are considering any SARM, start with start here, the SARMs side effects page and our bloodwork guide, and check the batch’s lab report (lab tests guide).
What reduces risk (and what doesn’t)
- Knowing what you take: an independent, batch-specific certificate of analysis.
- Bloodwork: testosterone, LH, FSH, SHBG, lipids and liver enzymes were the markers that moved in trials.
- Not stacking: the only human data on a combination (LGD-4033 plus MK-677) showed large drops in testosterone and HDL.
- What doesn’t help: “liver support” supplements have not been shown to prevent SARM liver injury, and lower doses still suppressed testosterone in trials.
Legal status and sport
No SARM is FDA-approved; the FDA says SARM products are unapproved drugs illegally sold as supplements, and it sent warning letters to sellers in December 2025. In Australia, SARMs are prescription-only. All SARMs are banned in sport at all times. See are SARMs legal?
Frequently asked questions
What is the safest SARM?
None is proven safeEvidence: Trial
No SARM is approved or proven safe. Ostarine is the most studied, with Phase 2 and Phase 3 trials in over 1,000 people, but it lowered testosterone and HDL and has case reports of serious liver injury.
What is the safest SARM for beginners?
NoneEvidence: Trial
There is no safe SARM for beginners. Ostarine is often suggested because it has the most data, but it still lowered testosterone and HDL at 1–3 mg/day in trials.
Which SARM has the fewest side effects?
UnknownEvidence: Limited
Most SARMs have never been tested in people, so this is not known. Among those that have, LGD-4033 suppressed testosterone at only 1 mg/day and RAD-140 raised liver enzymes in about half of trial patients.
Are SARMs safer than steroids?
Never tested head to headEvidence: Limited
No study has compared them directly. SARMs avoid conversion to estrogen and DHT, but they still suppress testosterone, lower HDL and have serious liver injury case reports.
Is MK-677 safer than SARMs?
Not clearly; different risksEvidence: Trial
MK-677 does not suppress testosterone much, but it raises appetite, water retention and blood sugar. Trials in frail older adults showed a heart-failure signal.
Is cardarine safe?
No; cancers in animalsEvidence: Animal
Cardarine is not a SARM, and its development was stopped after 2-year studies found cancers in many organs of rats and mice. No long-term human data exist.
Do any SARMs not suppress testosterone?
NoEvidence: Trial
No SARM tested in people left testosterone untouched. Cardarine, SR9009 and MK-677 are not SARMs and act differently, but each has its own risks.
Sources
- The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial
- EMERALD study protocol (ISRCTN12213700, University of Liverpool, version 6.0, 2021): a window of opportunity study of enobosarm in ER+/AR+ early breast cancer
- Drug-Induced Liver Injury From Enobosarm (Ostarine), a Selective Androgen Receptor Modulator
- The safety, pharmacokinetics, and effects of LGD-4033, a novel nonsteroidal oral, selective androgen receptor modulator, in healthy young men
- Ligandrol (LGD-4033)-Induced Liver Injury
- A First-in-Human Phase 1 Study of a Novel Selective Androgen Receptor Modulator (SARM), RAD140, in ER+/HER2- Metastatic Breast Cancer
- Myopericarditis Following Use of Selective Androgen Receptor Modifier "RAD-140"
- Selective androgen receptor modulator abuse-induced heart failure: catastrophic effects of RAD-140 (Testolone)
- 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
- Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet
- LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report
- Rat carcinogenicity study with GW501516, a PPAR delta agonist (Geiger et al., The Toxicologist 2009, abstract 895)
- FDA: Certain bodybuilding products put consumers at risk for heart attack, stroke, serious liver damage and more (content current as of 2 December 2025)
- FDA Warning Letter to an online seller of products marketed as SARMs (MARCS-CMS 719257), 12 December 2025
- Therapeutic Goods (Poisons Standard—June 2026) Instrument 2026 (F2026L00633)
- Acute Liver Failure in an Adolescent Following Use of the Synthetic REV-ERB Agonist SR9009
- YK11 induces oxidative stress and mitochondrial dysfunction in hippocampus: The interplay between a selective androgen receptor modulator (SARM) and exercise
