Testolone (RAD-140)

Testolone (RAD-140) is a selective androgen receptor modulator, or SARM (a drug that switches on the body’s testosterone-sensing receptor in a targeted way). It is a small molecule made in a lab — not a peptide, and not an anabolic steroid. It was created as an experimental drug, was never approved for any use, and is now widely sold online for building muscle. That is true even though there are no published human studies showing it works for that. The only human data we have come from cancer research, and the compound carries some real, documented harms.

What it is

RAD-140 attaches to the androgen receptor (the cell switch that responds to testosterone) and turns it on. In early lab work, it was designed to be selective — meaning it would mostly build muscle and bone while having a weaker effect than testosterone on tissues like the prostate. Whether that selectivity actually holds up in people is not well understood. It was discovered by Radius Health, which is why you’ll see it called RAD140 in the research. Worth noting: Radius didn’t study it for muscle building at all. They looked at it as a pill for a specific kind of breast cancer that is fueled by both androgen and estrogen receptors (AR-positive, ER-positive).

The claims

In fitness, bodybuilding, and biohacking circles, RAD-140 is sold and used as an oral “muscle-building” or “lean mass / strength” product. It’s often pitched as a gentler alternative to anabolic steroids or testosterone, with fewer side effects. You’ll find it sold as a “research chemical,” labeled “not for human consumption,” or hidden inside products dressed up to look like dietary supplements. The promise of big muscle gains with almost no androgenic side effects is just a marketing pitch. There are no published, controlled human trials in healthy people showing it improves body composition or performance.

What the evidence actually shows

The original pharmacology paper (Miller et al., 2011) describes how RAD140 was discovered, how it binds the androgen receptor, and how it built muscle in rodents, with some activity in a primate model. That’s animal and test-tube (in-vitro) data — not proof it works in humans. Yu et al. (2017) found that RAD140 was active against AR-positive/ER-positive breast cancer in lab models, working through a distinct mechanism, and that became the reason to test it in the clinic. The only time humans have actually taken it was in cancer research (a Phase 1 trial, NCT03088527). There is a first-in-human Phase 1 report in a type of metastatic breast cancer (ER-positive, HER2-negative), but no fitness or body-composition results in healthy people have been published. Bottom line: there is no human evidence that it works for the fitness uses people buy it for, and the muscle-building rationale rests entirely on preclinical (animal and lab) data.

Legal and regulatory status

The U.S. FDA says SARMs, including RAD-140, are not legal dietary-supplement ingredients and are not FDA-approved for any use. The FDA has warned both consumers and companies about SARMs, pointing to risks such as liver injury and a higher chance of heart attack and stroke, and it has sent warning letters to companies selling SARMs in supplement-style products. RAD-140 and most SARMs are not currently listed as DEA controlled substances. A “SARMs Control Act” has been introduced in Congress several times to make SARMs controlled substances, but as of June 2026 it has not been confirmed as law — treat it as proposed, not passed. SARMs are also a separate thing from anabolic-androgenic steroids like oxandrolone (a Schedule III controlled substance under the Anabolic Steroid Control Act), which is part of why a separate, SARMs-specific law has been proposed.

In sport, SARMs including RAD140/Testolone are banned at all times — both in competition and out of it — under the WADA Prohibited List, Section S1 Anabolic Agents. Specifically, they fall under S1.2, “Other Anabolic Agents,” where SARMs are spelled out by name (RAD140 is listed alongside andarine, ostarine, LGD-4033, S-23, and YK-11). RAD-140 is a common reason athletes fail drug tests, and it can be detected in anti-doping testing.

Safety

• Drug-induced liver injury (documented in humans): A published case report describes cholestatic liver injury (a type of liver damage where bile flow is blocked) linked to RAD-140 taken in bodybuilding supplements (Barbara, Dhingra & Mindikoglu, 2020). The products involved were “Alpha Bolic” (RAD-140) and “Alpha Elite” (RAD-140 and LGD-4033). SARM-related liver harm, including from RAD-140, is also covered in NIH LiverTox and in other published case reports.
• Testosterone/HPG-axis suppression: Because it turns on the androgen receptor, RAD-140 is expected to lower the body’s own testosterone and the hormones that signal it (LH and FSH, the pituitary signals that tell the body to make testosterone). This kind of suppression is a known effect across the SARM class. Hard numbers specific to RAD-140 in humans are limited.
• Lipids: As a group, SARMs are linked to drops in HDL cholesterol (the “good” cholesterol), best documented for ostarine (enobosarm). Human data on RAD-140’s specific effect on blood fats are limited.
• Product-quality risk: When researchers independently tested products sold as SARMs (Van Wagoner et al., JAMA 2017), they found many were mislabeled, underdosed, contained unapproved drugs, or contained none of the ingredient on the label — a real-world hazard for anyone buying these products.

A quick note on harms that get pinned on the wrong drug: some effects you’ll see blamed on RAD-140 online actually come from other compounds. Vision problems (yellow-tinged vision, trouble seeing at night) are reported with andarine (S-4), a different SARM. Cancer in multiple organs seen in long-term rodent studies belongs to GW-501516 (cardarine), which is a PPARδ agonist (a different class of drug entirely), not a SARM. Neither of these should be blamed on RAD-140.

Bottom line

RAD-140 is an experimental, non-approved SARM with no human evidence that it works for fitness, a hormone-suppressing profile typical of its class, at least one documented case of serious liver injury in a person, frequent product mislabeling, and banned status in sport. The strongest data are preclinical (from animals and lab dishes). The marketing promise of safe, effective muscle gain is not backed by published human trials.

Evidence grade: 3/10 · Animal only.

Sources

• Miller CP, et al. Design, Synthesis, and Preclinical Characterization of the SARM RAD140. ACS Med Chem Lett. 2011. PMID 24900290
• Yu Z, et al. SARM RAD140 Inhibits the Growth of Androgen/Estrogen Receptor–Positive Breast Cancer Models with a Distinct Mechanism of Action. Clin Cancer Res. 2017. PMID 28974548
• ClinicalTrials.gov NCT03088527 — Phase 1 study of RAD140 in AR+/ER+ metastatic breast cancer
• Barbara M, Dhingra S, Mindikoglu AL. Drug-Induced Liver Injury Associated With Alpha Bolic (RAD-140) and Alpha Elite (RAD-140 and LGD-4033). ACG Case Rep J. 2020. PMID 33062783
• Van Wagoner RM, et al. Chemical Composition and Labeling of Substances Marketed as SARMs and Sold via the Internet. JAMA. 2017. PMID 29183075
• NIH LiverTox — Selective Androgen Receptor Modulators
• U.S. FDA — warnings against SARMs in body-building products
• WADA Prohibited List — SARMs (S1.2); GW-1516 (S4.5)