RAD-140 (Testolone) and Gynecomastia: What the Evidence Shows

Key takeaways

Does RAD-140 Cause Gynecomastia? The Short Answer

RAD-140 (testolone) is a non-steroidal selective androgen receptor modulator (SARM). In contrast to traditional anabolic-androgenic steroids, SARMs were designed to preferentially engage androgen receptors in specific tissues, primarily muscle and bone, rather than acting uniformly across all androgen-sensitive tissue. Because RAD-140 is not a steroid, it is not a substrate for the aromatase enzyme, meaning it cannot be converted directly into estradiol the way testosterone and many anabolic steroids can. On this narrow pharmacological point, the argument that RAD-140 avoids the classic aromatization route to gynecomastia has some basis in its design.

That said, the absence of direct aromatization does not mean gynecomastia has been absent from real-world reports. A case published in JCEM Case Reports in 2024 described a 40-year-old man who developed bilateral gynecomastia and biochemical hypogonadotropic hypogonadism alongside a six-month history of using commercially available performance-enhancing supplements for gym workouts. Testing of the products he had used found they contained amounts of RAD-140, a selective androgen receptor modulator, alongside MK-677 (a growth hormone secretagogue) and cardarine, all of which the authors describe as banned performance-enhancing drugs. In that case, cessation of the supplements led to full resolution of symptoms, including normalization of the hypogonadotropic hypogonadism.

This distinction matters clinically. The evidence base does not show that the RAD-140 molecule itself directly produces breast tissue growth through an estrogenic mechanism the way anabolic steroids do. The documented case involved a multi-ingredient, unregulated product rather than isolated, verified testolone, and the mechanism the authors and other endocrinology literature point to is secondary hormonal disruption, not direct aromatization of the molecule.

The Proposed Mechanism: Hormonal Disruption Rather Than Aromatization

SARMs, including RAD-140, are understood to suppress the hypothalamic-pituitary-gonadal axis: androgen receptor stimulation signals to the brain that circulating androgen is sufficient, which reduces luteinizing hormone (LH) and follicle-stimulating hormone output and, in turn, lowers endogenous testosterone production. Because estrogen in men is derived largely from aromatization of testosterone in peripheral tissue, a drop in testosterone can shift the testosterone-to-estrogen ratio even without any new estrogen being produced, and relative estrogen dominance is a recognized contributor to gynecomastia. It is important to note that this specific pathway has not been directly measured with serum estradiol assays in RAD-140 users in the published case reports; it remains a plausible mechanistic explanation rather than a confirmed one.

The JCEM case report authors also noted a separate, unrelated line of research: RAD-140 is currently undergoing testing as a potential treatment for androgen receptor-positive metastatic breast cancer, through suppression of estrogen receptor 1 and its downstream pathway. This indicates the molecule can interact with estrogen receptor signaling in an oncology research context, but this concerns antitumor mechanisms in breast cancer cells, not evidence that RAD-140 itself raises circulating estradiol in healthy users.

Independent of aromatization, suppression of endogenous testosterone during SARM use can itself produce clinical hypogonadism, and the case literature documents this directly. The patient in the JCEM report presented with biochemical hypogonadotropic hypogonadism alongside the gynecomastia, consistent with a suppression-driven hormonal disruption model rather than a direct estrogenic effect of testolone.

Why SARM Products Marketed Online Are a Poor Test Case

A central complication in interpreting any RAD-140 gynecomastia report is that products sold online under names like "RAD-140" or "testolone" are frequently mislabeled, underdosed, overdosed, or substituted with other compounds. The foundational analysis on this question, published in JAMA in 2017 by Van Wagoner and colleagues, tested 44 products purchased online and marketed as SARMs; only 23 of the 44 products (52%) actually contained one or more of the SARMs ostarine, LGD-4033, or andarine, while an additional 17 products (39%) contained a different unapproved compound not listed on the label.

A UK-focused analysis by Leaney and colleagues, published in Drug Testing and Analysis, examined dietary supplements marketed to UK consumers as containing SARMs and set out specifically to determine the accuracy of their labeling. Of 20 analyzed samples, only six were found to be in accordance with their labeling, and where SARMs were actually detected, discrepancies were common between the measured concentrations and the amounts stated on the packaging.

A more recent analysis of SARM products purchased online from Italy similarly used chemical testing (mass spectrometry and nuclear magnetic resonance) on 13 products. Qualitative analysis confirmed the presence of the SARM stated on the label in about 70% of samples; in roughly 23% of samples the expected SARM was absent but a different one was found instead, and one sample contained no SARM at all. Across these independent investigations from different countries, mislabeling, substitution, and dosing inaccuracy are a consistent finding, not an isolated one.

This means a person who reports gynecomastia after taking a product labeled RAD-140 may, in fact, have been exposed to an undisclosed compound with genuine estrogenic activity, rather than to testolone itself. The 2024 JCEM case is illustrative precisely because it involved a multi-supplement regimen containing RAD-140 alongside undisclosed additional agents, and the authors explicitly warned that such commercially available performance-enhancing supplements commonly contain undisclosed and unapproved substances, increasing the risk of adverse effects. This confounding is a major reason the evidence connecting RAD-140 specifically, as opposed to the unregulated products sold under that name, to gynecomastia remains limited to a small number of case reports.

What the Broader SARM Literature Says About Relative Risk

The JCEM case report authors note that, due to fewer observed effects such as gynecomastia or testicular atrophy compared with anabolic-androgenic steroids, SARMs are often mistaken by recreational users as a safer alternative to steroids. This framing itself signals caution: a lower reported rate of a side effect in scattered case literature is not the same as an absence of risk, and the same case report documents an instance in which gynecomastia occurred regardless of the theoretical mechanistic advantage.

Grading the strength of the evidence honestly: the case literature (a small number of published reports) shows gynecomastia occurring in the context of RAD-140-containing product use, but no dose-ranging, controlled human trial has systematically measured breast tissue changes or serum estradiol during isolated, verified RAD-140 administration. The overall evidence should be described as mechanistically plausible via secondary hormonal suppression and product contamination, but not established as a direct estrogenic effect of testolone, and it is clearly weaker in scale and rigor than the well-documented aromatization-driven gynecomastia risk associated with testosterone and many anabolic steroids.

Other Documented Risks of RAD-140 Worth Weighing Alongside Gynecomastia

Gynecomastia is not the most severe or best-documented harm associated with RAD-140 in the case-report literature; liver injury and cardiac effects have considerably more case-report support. A report published in the Ochsner Journal described a 24-year-old man who presented with a two-week history of diffuse abdominal pain, scleral icterus, pruritus, and jaundice after taking RAD-140 for muscle growth for five weeks. He had a cholestatic pattern of liver injury with a peak total bilirubin of 38.5 mg/dL, and liver biopsy supported a diagnosis of RAD-140-associated liver injury with intracytoplasmic and canalicular cholestasis and minimal portal inflammation. Symptoms and liver injury resolved after he stopped taking the product; the authors noted this was, to their knowledge, the third published case of liver injury specifically associated with RAD-140 and the sixth overall involving a SARM.

A separate case published in Australian Prescriber described a man who had procured RAD-140 online, used it for two months, and developed cholestatic hepatitis confirmed on biopsy; a validated adverse-drug-reaction scoring tool indicated the liver injury was a probable reaction to the drug. A third case, published in Cureus in 2024, described a 29-year-old man who developed jaundice and elevated liver enzymes after three months of RAD-140 use, with a liver ultrasound revealing hepatic steatosis and a hyperechoic lesion; his symptoms resolved after he discontinued the product, though the authors cautioned that the long-term effects and risks of SARM use remain unclear.

Cardiac harm has also been reported. A case published in JACC: Case Reports in 2024 described a 16-year-old boy who developed myopericarditis after a single dose of RAD-140, presenting with chest pain that radiated to his left arm; the authors theorized this class of drugs may interfere with enzymes involved in steroidogenesis, contributing to cardiovascular effects. A separate case published in Cureus in 2022 described a young man who developed shortness of breath after self-medicating with RAD-140 for performance enhancement and muscle building, leading to a presumptive diagnosis of RAD-140-induced acute myocarditis. These reports, together with the liver injury cases, indicate that gynecomastia is a comparatively minor entry on the list of serious harms reported with RAD-140 use outside of clinical supervision.

Regulatory Status and Anti-Doping Position

No SARM, including RAD-140, has been approved by the FDA for any human use. The FDA's current consumer guidance states that although body-building products containing SARMs are often marketed as dietary supplements, they are not dietary supplements; instead, they are unapproved drugs that the FDA has not reviewed for safety or effectiveness. The agency states that life-threatening reactions, including liver injuries requiring hospitalization, have occurred in people taking SARM-containing products, and lists additional potential harms including increased risk of heart attack or stroke, psychosis and hallucinations, sleep disturbances, sexual dysfunction, infertility, pregnancy miscarriage, and testicular shrinkage.

SARMs are also prohibited in Olympic and other WADA-code sport at all times, and the World Anti-Doping Agency maintains a public list of prohibited substances that includes RAD-140 and other SARMs by name; athletes have tested positive after using contaminated supplements rather than knowingly dosing a prohibited SARM, which is one reason regulators and anti-doping bodies treat these unregulated products as a distinct risk category from pharmaceutical-grade investigational drugs studied under controlled conditions.

Bottom Line

The pharmacological argument that RAD-140 should not cause gynecomastia through aromatization is reasonable as far as it goes: the molecule is not a substrate for aromatase. But this argument does not fully hold up against the published clinical record, where at least one detailed case documents gynecomastia occurring in a user of a RAD-140-containing product. The most defensible reading of the evidence is that any gynecomastia risk associated with RAD-140 use is likely driven by suppression of the hypothalamic-pituitary-gonadal axis and by the substantial risk that products sold as RAD-140 online are mislabeled, underdosed, or adulterated with other hormonally active substances, rather than by a direct estrogenic action of testolone itself. Because no SARM is approved for human use and no controlled human trial has systematically assessed breast tissue changes with verified RAD-140 administration, the evidence should be considered preliminary, and the far better-documented risks of liver injury and myocarditis associated with RAD-140 in case reports warrant at least as much attention as gynecomastia.

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