SARMs Complete Guide: Ostarine, Ligandrol, RAD-140

SARMs (selective androgen receptor modulators) are often marketed as a safer alternative to anabolic steroids, and that framing is mostly marketing. The short answer: the three most common SARMs (ostarine, ligandrol, RAD-140) are tissue-selective, which is a real difference, but they still suppress testosterone, still stress the liver, still show up in doping controls, and are sold through a largely unregulated market where mislabeling and contamination are rampant. Treat them with the same respect for bloodwork, source verification, and PCT as any AAS.

How SARMs work and where selectivity helps

SARMs bind the same androgen receptor as testosterone and AAS, but with conformational changes that favor anabolic tissue (muscle and bone) over androgenic tissue (prostate, skin). This is where the “selective” in the name comes from. They do not aromatize to estrogen and do not reduce to DHT, which removes two major side-effect pathways.

Selectivity is incomplete in practice. Real SARMs still suppress the HPG axis, still raise liver enzymes in some users, and carry unknown long-term risks because almost none have completed Phase III human trials. The selectivity is a matter of degree.

Ostarine (MK-2866, Enobosarm)

Ostarine (MK-2866 / Enobosarm) is the mildest and most studied of the three. It has an estimated 24-hour half-life, supporting once-daily oral dosing. Clinical trials at 1 to 3 mg produced dose-dependent lean mass gains. The dataset rates hepatotoxicity as mild.

Ostarine is the least suppressive of the three at low doses, which is why the “SARMs don’t need PCT” myth has some basis in very short, low-dose ostarine-only runs. At the doses used in practice (typically higher than the clinical 1 to 3 mg), suppression becomes real. Plan for a mini-PCT on any ostarine run longer than 6 weeks or any stack.

Detection: ostarine glucuronide and the M4b metabolite are detectable for roughly 6 to 9 days after a microdose (Hansen et al., 2020).

Ligandrol (LGD-4033)

Ligandrol (LGD-4033) is more potent than ostarine. The dataset records a half-life of about 30 hours, Cmax near 498 ng/dL, Tmax around 3 hours, and bioavailability near 60%. Phase I trials at 0.1 to 1 mg produced dose-dependent lean mass gains, and suppression of endogenous testosterone becomes evident at higher doses.

Ligandrol is where the “SARMs are suppressive” reality becomes clear. At common off-label doses, LH and FSH drop, total testosterone falls, and a structured PCT is warranted. Lipid shifts (HDL suppression) and liver enzyme elevation also occur.

Detection: dihydroxylated long-term metabolites (M5a, M2d) extend detection to roughly 21 days (Bisollon et al., 2021).

Testolone (RAD-140)

Testolone (RAD-140) is the most potent of the three and was originally investigated for breast cancer cachexia. The dataset records a half-life of about 44.7 hours, Cmax near 447 ng/dL, Tmax around 6 hours, and bioavailability near 60%. Once-daily oral dosing is typical, and accumulation occurs over the first week.

RAD-140 drives rapid strength and lean mass increases, but the potency also drives measurable suppression, lipid disruption, and liver enzyme elevation at common off-label doses. Case reports of severe hepatotoxicity with RAD-140 have appeared in the literature, which is unusual for a SARM.

Detection: the RAD-140 sulfate phase I metabolite is detectable for roughly 5 to 9 days after a microdose, with parent RAD-140 in plasma for at least 8 days (Fitzgerald et al., 2022).

The suppression question

This is the biggest area of misinformation. Many SARMs are suppressive, some significantly. Ligandrol and RAD-140 suppress endogenous testosterone meaningfully at typical doses, sometimes to hypogonadal levels. Ostarine is less suppressive at low doses but not zero.

The practical implication: most SARM cycles warrant a PCT, especially if longer than 6 weeks or if stacking multiple SARMs. See our PCT fundamentals for SERM protocols. The “SARMs don’t need PCT” line is true for very short, low-dose ostarine-only cycles and false for almost everything else.

Draw LH, FSH, and total testosterone before and after any SARM cycle. If suppression is present, a SERM-based PCT using Clomid or Nolvadex is the standard recovery approach.

Source quality: the single biggest harm

This deserves its own section. The SARM market is largely unregulated, and independent testing has repeatedly found that products sold as SARMs contain unlisted steroids (sometimes trenbolone or Superdrol), no active compound at all, or dosages far above what is on the label.

A user who thinks they are taking 10 mg of ostarine may be taking 30 mg of a liver-toxic oral steroid. This is a contamination risk that can cause real harm, including the severe hepatotoxicity and lipid damage the user thought they were avoiding by choosing a “SARM.”

Detection and anti-doping

All three compounds are WADA-prohibited at all times. WADA added SARMs to the Prohibited List in 2008, and accredited labs screen for them. The “SARMs aren’t tested for” claim is outdated. Ostarine has shown up in positive tests from contaminated supplements, which is why athletes must verify every supplement through a certification program like Informed Sport.

Detection windows vary by compound but range from days to weeks, with some metabolites persisting longer. This is harm-reduction context, not instructions for evading a test.

FAQ

Do SARMs suppress natural testosterone?

Yes, most of them. Ligandrol and RAD-140 suppress meaningfully at typical doses. Ostarine is less suppressive but not zero at effective doses. Plan for a PCT after any SARM cycle longer than 6 weeks or any stack.

Which SARM is most potent?

RAD-140 (testolone) is generally considered the most potent of the three for strength and mass, followed by ligandrol, then ostarine. More potency also means more suppression and side-effect risk.

Are SARMs liver toxic?

Mild hepatic stress is common across the class. Severe hepatotoxicity is rare but documented, especially with RAD-140 and with mislabeled or contaminated products. Draw AST, ALT, and GGT on any SARM cycle.

How long are SARMs detectable?

Windows vary. Ostarine roughly 6 to 9 days, ligandrol up to 21 days, RAD-140 roughly 5 to 9 days from microdose studies, with parent RAD-140 in plasma for at least 8 days. WADA screens for all three.

Can SARMs replace testosterone in a cycle?

Some advanced protocols stack SARMs with a testosterone base, but SARMs do not replace testosterone as a base compound. Running a SARM alone still suppresses endogenous testosterone. See our first cycle guide for base-compound reasoning.

Sources

• Hansen J, et al. Detection of ostarine and its metabolites in human urine. Drug Testing and Analysis. 2020.
• Basaria S, et al. Phase 1B trial of the SARM enobosarm in healthy men. Journal of Cachexia, Sarcopenia and Muscle. PMID: 24002685.
• Bisollon M, et al. Characterization of LGD-4033 metabolites. Drug Testing and Analysis. 2021.
• Fitzgerald P, et al. Identification of RAD-140 metabolites. Metabolites. 2022.
• World Anti-Doping Agency. Prohibited List. wada-ama.org.