What RAD-140 Actually Is
RAD-140, sold under the name testolone, is a non-steroidal selective androgen receptor modulator. It was developed by Radius Health and first described in the literature by Miller et al. in 2011 in ACS Medicinal Chemistry Letters, as a preclinical characterisation in rodents and primates. That is where it starts: a molecule designed to hit the androgen receptor in muscle and bone while doing less at the prostate than testosterone would.
It is a genuine SARM, which is worth saying because most of what gets sold under that banner is not. MK-677 (ibutamoren) sits on the same shelf in every shop that sells either, and it is not a SARM at all — it is a growth hormone secretagogue with an entirely different mechanism. If you are trying to work out what you are actually looking at, start with what is and is not a SARM.
How It Works
Testosterone binds the androgen receptor everywhere it finds one, which is why it grows muscle and also acts on the prostate, skin and hair follicles. A SARM is an attempt to keep the first part and lose the rest: bind the same receptor, but with tissue selectivity, so the anabolic signal in muscle and bone arrives without the same activity elsewhere.
In the preclinical work, RAD-140 did that. It produced anabolic activity in muscle with less prostate stimulation than testosterone in the animal models used. Whether that selectivity holds in a human male taking it to get bigger is a separate question, and one nobody has run the trial to answer.
What Human Research Exists
This is the part that gets skipped everywhere else, so read it slowly.
There is exactly one first-in-human study
A phase 1 study published in Clinical Breast Cancer in 2022 enrolled 22 heavily pretreated postmenopausal women with ER+/HER2- metastatic breast cancer. It was a dose-escalation safety study in cancer patients — the objective was to find the maximum tolerated dose and characterise the pharmacokinetics, not to measure muscle or strength.
What that trial reported: the most frequent treatment-emergent adverse events were elevated AST in 59.1% of participants, elevated ALT in 45.5%, and raised total bilirubin. In other words, the single human trial of this compound found liver enzyme elevation in most of the people who took it. That is the headline finding, and it is the only human dataset there is.
There is no trial showing it builds muscle in people
A 2025 systematic review in Clinical Endocrinology gathered every randomised controlled trial of SARMs and physical performance it could find: nine trials, 970 patients, mean age 57. Six compounds were covered — LGD-4033, PF-06260414, GSK2881078, GTx-024, MK-0773 and OPK-88004.
RAD-140 is not on that list. Not because the review missed it, but because the trial does not exist. Every claim you will read about what RAD-140 does for lean mass in a healthy adult is extrapolated from rodents, or from someone's log.
What Is Documented Is the Harm
The human literature on RAD-140 is not efficacy data. It is case reports, and there are a lot of them.
Liver
Drug-induced liver injury linked to RAD-140 has appeared in the published record every year since 2020: ACG Case Reports Journal, 2020; Ochsner Journal, 2022; Journal of Medical Case Reports, 2023; Australian Prescriber, 2024, reporting severe liver injury after use for bodybuilding; and a 2025 case in ACG Case Reports Journal of cholestatic injury that needed corticosteroids to resolve.
Worth being clear about something, because I take liver support myself and it would be easy to imply more than is true: no liver supplement has been shown to prevent this. Milk thistle, TUDCA, NAC — none of them have trial evidence for protecting against SARM-induced liver injury. Taking them is not a reason to be relaxed about the risk, and monitoring bloods is not the same as preventing damage. It tells you it is happening, which is better than not knowing, and that is all it does.
Heart
Case reports also describe acute myocarditis, myopericarditis and heart failure in users of RAD-140. These are individual cases, not incidence rates, and a case report cannot tell you how likely something is. It can tell you the thing happens.
Suppression, and tendons
Suppression of natural testosterone production follows from the mechanism — the body reads the androgen signal and turns down its own output. A 2025 systematic review in the American Journal of Sports Medicine on SARM abuse in athletes also flags tendon rupture alongside liver injury and myocarditis.
You Probably Are Not Getting RAD-140
Before any of the above matters, there is the question of what is actually in the bottle. A 2017 analysis published in JAMA bought 44 products sold online as SARMs and put them through a WADA-accredited lab.
- Only 23 of 44 (52%) contained any SARM at all.
- 17 (39%) contained a different unapproved drug — including ibutamoren, GW501516 and SR9009.
- 4 (9%) contained no active compound whatsoever.
- 11 (25%) contained substances not listed on the label.
- Only 18 (41%) matched the amount of active compound the label claimed.
That is the base rate for this market. Every risk described further up assumes you got the compound on the label; roughly half the time you did not, and a quarter of the time you got something nobody told you about.
What Eight Weeks Looked Like for Me
I ran RAD-140 for eight weeks. The gains were good — genuinely, that is the honest report, and pretending otherwise to make a safety point would be its own kind of dishonesty. Strength moved and I held size well.
I took liver support throughout and I had bloods done. Both of those were deliberate, and the second one is the part that actually matters: without bloodwork you have no idea what is happening to your liver enzymes or your own testosterone production until something makes itself obvious.
On suppression, I have an advantage that most people reading this do not. I am on TRT anyway, so my testosterone is coming from outside regardless and shutdown is not the problem for me that it is for someone with a working axis they are about to switch off. That is not a reassurance I can pass on to you. It is the opposite — the reason it was a lower-risk decision for me is a reason it is a higher-risk one for you, and recovery of natural production after suppression is not guaranteed to be quick or complete.
I am not giving doses here and I am not going to. There is no established human dosing for this compound outside a phase 1 cancer trial, and a number from my log would read as a recommendation no matter how it was framed.
Where Ireland Stands
RAD-140 has no medicinal licence from the Health Products Regulatory Authority or the European Medicines Agency, and it is not an approved ingredient in a food supplement. It is sold as a research chemical, which is a label about legal category rather than about quality. It is not a controlled substance under the Misuse of Drugs Acts.
For anyone tested, it is straightforward: SARMs are on the WADA prohibited list at all times, in and out of competition. Detection windows for these compounds are long and the assays are good.
The Short Version
- RAD-140 (testolone) is a real SARM, unlike MK-677, which is sold as one and is not.
- One first-in-human trial exists: 22 breast cancer patients, and its main finding was liver enzyme elevation in 59.1% (AST) and 45.5% (ALT) of participants.
- No randomised trial has ever tested RAD-140 for muscle or physical performance in humans. The 2025 systematic review of SARM performance RCTs covers six other compounds.
- The human record that does exist is case reports: drug-induced liver injury every year since 2020, plus myocarditis, myopericarditis, heart failure and tendon rupture.
- Liver supplements have no evidence of preventing SARM liver injury. Bloodwork detects a problem; it does not stop one.
- Suppression of natural testosterone follows from the mechanism, and recovery is not guaranteed.
- In a JAMA analysis, only 52% of products sold as SARMs contained a SARM and only 41% matched their own label.
- No HPRA or EMA licence in Ireland. Banned by WADA at all times.
Related Reading
SARMs in Ireland: what they are, what they are not, and where the law sits · MK-677 (ibutamoren): not a SARM, and not approved · Why I test bloods before changing anything