Peptide & Experimental

RAD140 (Testolone)

Selective androgen receptor modulator (SARM) · Testolone, SARM

RAD140, called Testolone in the scene, is the best-known representative of the SARMs, the selective androgen receptor modulators. The idea behind it is clever pharmacology: the muscle effect of testosterone, but as far as possible without its effects on the prostate, skin and hormonal system. That RAD140 acts on the human androgen receptor has been shown; for muscle building in humans, by contrast, there is not a single controlled study.

In brief

RAD140 is an orally active, non-steroidal molecule that activates the androgen receptor and acts tissue-selectively in animals, strongly in muscle, sparing the prostate. The only clinical study in humans tested it in 22 women with metastatic breast cancer: the effect on the receptor was clearly measurable, but elevated liver values were the most common side effect, with AST rising in 59.1 percent. Training forums consistently report marked gains in muscle and strength, together with suppressed natural testosterone production. RAD140 is not approved anywhere, is on the WADA Prohibited List, and products from the internet often contain something other than what is declared.

What it is

SARM stands for selective androgen receptor modulator. Testosterone acts strongly on muscle and bone, but also on the prostate, skin, hair follicles and the body’s own hormonal feedback loop. Pharmaceutical research therefore wanted to build molecules that target the same receptor, but with different strength depending on the tissue: full effect in muscle, as little as possible elsewhere. That selective receptor modulation works in principle is shown by medicine with the estrogen receptors, where tamoxifen has long been standard.

RAD140 was developed by the biotech company Radius Health and described in 2011 as a potent, orally bioavailable, non-steroidal SARM. It was initially intended for muscle wasting, later for certain forms of breast cancer. Unlike many anabolic steroids, it does not have to be injected.

How it works

RAD140 binds to the androgen receptor and activates it. In experiments with castrated rats, it acted androgenically in a tissue-specific way while largely sparing the prostate, exactly the profile SARMs promise. In humans, the effect on the receptor has since been directly demonstrated: in the phase 1 study, the binding protein SHBG fell in 18 of 18 patients, the androgen marker PSA rose in 16 of 20, and tumor biopsies showed that the receptor was engaged. The half-life was 44.7 hours.

The same receptor effect explains the downside. Like testosterone, RAD140 signals to the hormonal feedback loop that there is enough, the pituitary gland throttles LH and FSH, and the body’s own testosterone production falls. For the related SARM LGD-4033, this has been shown in a placebo-controlled study in 76 healthy men: lean mass rose after just 21 days, while testosterone, SHBG and protective HDL cholesterol fell, and everything normalized after stopping.

What users report

In training forums the reports are remarkably consistent: several kilos of lean mass, marked jumps in strength and faster recovery within a few weeks, on a scale reminiscent of mild steroid cycles. Just as consistently reported is the other side, a suppression of natural testosterone production measurable in blood tests, with fatigue, loss of libido and low moods after the cycle. The scene counters this with so-called post-cycle therapy, that is, with further medicines meant to repair the side effect. Experienced users stress blood tests before and after the cycle. All of these are user reports, not study data.

The forums also claim that RAD140 is good for the brain. Behind this is a 2014 paper in which, in cell culture, it was as effective as testosterone against the death of nerve cells and in rats protected nerve cells against a neurotoxin. That is an interesting laboratory signal for which there are no human data.

What is well supported

The pharmacological principle is well supported. RAD140 measurably activates the androgen receptor in humans and acts tissue-selectively in animals. The phase 1 study in 22 heavily pretreated women with metastatic breast cancer also provided pharmacokinetics and first indications of antitumor activity: one partial remission and a clinical benefit rate of 18.2 percent after 24 weeks. The authors rated the safety profile as acceptable for this patient group.

For the SARM class as a whole, it is also established that lean mass increases in humans: under LGD-4033 it rose in a dose-dependent manner within just 21 days. That the idea is alive is shown by further research on SARMs against muscle wasting in old age and in cancer, one of the big unsolved problems of geriatric medicine.

What the studies show

LoRusso et al., Clinical Breast Cancer 2022 — the phase 1 study

First use in humans, open-label dose escalation in 22 postmenopausal women with ER-positive, HER2-negative metastatic breast cancer. The most common side effects were rises in AST in 59.1 percent, ALT in 45.5 percent and bilirubin in 27.3 percent. Serious grade 3 and 4 events occurred in 72.7 percent; events classified as treatment-related occurred in 17 of 22 patients, none of them grade 4. The receptor effect was clearly detectable via SHBG, PSA and biopsies. Muscle mass was not measured.

Van Wagoner et al., JAMA 2017 — what is in SARM products

44 products sold online as SARMs were analyzed according to anti-doping standards. Only 23, or 52 percent, contained a SARM at all; 17 contained other unapproved active substances, 4 no active substance at all, 11 undeclared substances. Only in 18 products, 41 percent, did the amount match the label.

Ladna et al., Journal of Medical Case Reports 2023 — liver injury

A 26-year-old man with no pre-existing conditions came to hospital with nausea, severe upper abdominal pain and jaundice; no cause other than RAD140 was found. After stopping, the liver values normalized within 2 months. It is one of several published cases of liver injury; in addition there are case reports of myocarditis and heart failure.

Where the data stop

The decisive gap: for muscle building with RAD140 there is no controlled study in humans. The only clinical study concerned women with advanced breast cancer and did not measure muscle mass at all. Further human data come from microdose studies for doping analysis, which were only about detection in urine. Everything on the muscle effect is animal model plus user report.

The advertising as a low-side-effect alternative to anabolic steroids does not fit the available data: frequent rises in liver values in the phase 1 study, several case reports of liver injury and, in controlled studies of the related LGD-4033, axis suppression and HDL lowering. How far the side effects in seriously ill cancer patients can be transferred to healthy athletes is an open question; there are no long-term data. And neuroprotection so far exists only in cell culture and rats.

Status, approval and legal

RAD140 is not approved as a medicine anywhere and is sold as a research chemical on the gray market. The US Food and Drug Administration (FDA) makes clear that SARMs are not dietary supplements but unapproved drugs, and warns of heart attack, stroke, liver injury up to liver failure, psychosis, sleep disorders, infertility and testicular shrinkage. In sports the situation is clear: the 2026 WADA Prohibited List names RAD140 explicitly in the group of anabolic agents, prohibited at all times, and it can be detected in urine via its metabolites. Because of contaminated products, a positive test can also affect people who did not take it knowingly. We do not give dosage information.

Safety

The documented risks concern the liver, the hormone axis and the heart. In the phase 1 study, elevated liver values were the most common side effect, and several cases of liver injury with jaundice have been documented in users, as well as cases of myocarditis. The body’s own testosterone production is suppressed, and with the related LGD-4033, HDL cholesterol fell in a dose-dependent manner. Because of its androgenic effect, RAD140 is particularly unsuitable for women and ruled out in pregnancy. Anyone with liver disease, cardiovascular risks or a wish to have children should stay away from it. Because of the unreliable product quality, you cannot be sure what you are taking when you buy it.

BK-Score Hype far ahead of evidence

Human evidence		2
Mechanism		6
Safety data		3
Hype gap		0
Track record of use		4

The substance is advertised as a low-side-effect alternative to anabolic steroids – controlled efficacy studies on muscle building in humans do not exist. The only clinical human study is an open-label phase 1 in 22 women with metastatic breast cancer (LoRusso, Clin Breast Cancer 2022): the receptor effect is confirmed via SHBG (fallen in 18 of 18), PSA (risen in 16 of 20) and tumor biopsies, muscle mass was not measured; the most common side effects were rises in AST and ALT (59.1 and 45.5 %), and grade 3/4 events occurred in 72.7 %. In addition there are microdose studies for doping analysis and several case reports of liver injury (including J Med Case Rep 2023) as well as myocarditis. Axis suppression and HDL lowering have been shown in placebo-controlled form for the related SARM LGD-4033. The FDA warns for the entire SARM class of liver failure, heart attack, stroke and infertility. Only 52 % of SARM products sold online contained a SARM at all (JAMA 2017). Not an approved medicine, named on the 2026 WADA list.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about RAD140 (Testolone)

What is RAD140?

A selective androgen receptor modulator, SARM for short, that activates the androgen receptor and in animals acts strongly in muscle but sparingly on the prostate. It was developed by Radius Health for muscle wasting and breast cancer and is not approved anywhere.

Does RAD140 build muscle?

In animal models yes, and users consistently report marked gains in muscle and strength. There is no controlled study in humans on muscle building. For the related SARM LGD-4033, a gain in lean mass within 21 days has been shown.

Is RAD140 harmful to the liver?

In the only clinical study, liver values rose in a large proportion of the patients, AST in 59.1 percent. In addition, there are several published cases of liver injury with jaundice in users; in the case of a 26-year-old described in detail, the values normalized after stopping.

Does RAD140 lower testosterone?

Yes, this is considered the most certain effect. SARMs signal to the hormonal feedback loop that there is enough androgen, and the body’s own production falls. For the related LGD-4033, the lowering of testosterone and HDL has been demonstrated in a placebo-controlled study.

Is RAD140 legal in Germany?

RAD140 is not approved as a medicine and is sold as a research chemical. In sports it is prohibited at all times under the WADA list. The US FDA classifies SARMs as unapproved drugs, not as dietary supplements.

Do SARM products contain what the label says?

Often not. In an analysis of 44 SARM products bought online, only 52 percent contained a SARM at all, and only in 41 percent did the amount match the label. A quarter contained undeclared substances.

The podcast episode (in German)

Episode 66