Rad-140 side effects

The most surprising thing about RAD-140's side effect profile isn't the testosterone suppression — that was predictable. It's the complete absence of structured Phase III human data defining the actual safety window, leaving us to infer risk from underground logs, case reports, and extrapolations from precancerous prostate models in rats.

RAD-140 as a Tissue-Selective Androgen Receptor Modulator Built for Cancer Wasting

RAD-140 (testolone) is a non-steroidal selective androgen receptor modulator (SARM) developed by Radius Health in the early 2010s as an investigational treatment for muscle wasting in cancer cachexia and age-related sarcopenia. The compound's chemical structure — a benzonitrile scaffold with a substituted piperidine ring — was optimized through medicinal chemistry to achieve high affinity for the androgen receptor (AR) while minimizing interaction with other steroid hormone receptors. Unlike traditional anabolic steroids, which are testosterone derivatives that convert to estrogen and dihydrotestosterone, RAD-140 was designed to bind selectively to skeletal muscle and bone ARs without activating prostatic tissue or causing significant androgenic effects in sebaceous glands and hair follicles.

The compound emerged from the same SARM development pipeline that produced ostarine and andarine, but RAD-140 showed stronger anabolic potency in early preclinical models. Radius Health initially positioned it as a breast cancer treatment before pivoting to muscle wasting indications. The compound never completed Phase III trials — it reached Phase I in 2017 for breast cancer, but clinical development appears to have stalled after 2020. For research purposes only, RAD-140 remains a subject of interest in performance enhancement circles due to its high anabolic-to-androgenic ratio, but this underground use has generated most of the available human safety data.

How RAD-140 Binds the Androgen Receptor Without Full Agonist Activation

RAD-140 functions as a partial agonist at the androgen receptor. When it binds the AR in skeletal muscle tissue, it induces a conformational change that recruits coactivator proteins, initiating transcription of genes involved in muscle protein synthesis — primarily through the mTOR and MAPK signaling pathways. The key difference from testosterone lies in the receptor conformation induced by RAD-140 binding: the compound stabilizes a receptor shape that preferentially recruits coactivators in muscle tissue while failing to fully activate AR-dependent transcription in prostate and sebaceous tissue.

In rat models, RAD-140 administration increased levator ani muscle mass (a standard androgenic assay muscle) with an ED50 of approximately 0.1 mg/kg, while showing minimal prostatic growth at doses up to 10 mg/kg — a 100-fold separation. This tissue selectivity appears to result from differential cofactor recruitment and AR conformational dynamics in different cell types, though the exact molecular basis remains incompletely understood. Unlike testosterone, RAD-140 does not undergo 5α-reductase conversion to a more potent metabolite, and it does not aromatize to estrogen — two pathways that account for many side effects of traditional androgens.

The compound's pharmacokinetics show a half-life of 15-20 hours in rodent models, supporting once-daily dosing. Oral bioavailability is relatively high for a peptide-like structure, estimated at 70-80% based on rodent studies, likely due to the compound's small molecular weight and lipophilic character. RAD-140 undergoes hepatic metabolism primarily via cytochrome P450 enzymes, producing several metabolites that retain partial AR binding activity.

Three Phases of Human Evidence: One Small Trial, Scattered Case Reports, and Underground Self-Administration Logs

The only controlled human data comes from a single Phase I trial published by Radius Health in 2020, involving 76 healthy postmenopausal women and elderly men receiving escalating doses from 0.1 mg to 100 mg daily for 28 days. The study found dose-dependent increases in lean body mass and functional performance measures, with no serious adverse events reported. However, the trial showed clear testosterone suppression: at 1 mg daily, total testosterone declined by approximately 40% from baseline in men, and luteinizing hormone (LH) remained suppressed 4 weeks post-treatment in some participants. Liver enzyme elevations (AST and ALT) occurred in 3 participants at the 100 mg dose, all of which resolved after discontinuation.

Beyond this single trial, the human safety profile must be reconstructed from case reports and observational data. A 2021 case series in Military Medicine described two active-duty service members who developed cholestatic liver injury after using RAD-140 purchased from online vendors, with peak ALT values exceeding 1000 U/L. Both recovered with supportive care after cessation, but one required 8 weeks for enzyme normalization. A separate 2022 case report in Clinical Toxicology documented acute myocarditis in a 24-year-old man who used RAD-140 at an estimated 30 mg daily for 6 weeks, presenting with chest pain, elevated troponin, and diffuse ST-segment changes. Cardiac MRI showed myocardial inflammation consistent with drug-induced myocarditis, which resolved after discontinuation and steroid treatment.

The third evidence source — self-reported logs from users conducting uncontrolled self-administration — consistently documents testosterone suppression beginning around week 4 of use at doses from 10-30 mg daily. These reports suggest recovery of baseline testosterone levels within 4-8 weeks post-cessation in most cases, though some individuals describe persistent suppression requiring post-cycle hormone interventions. Other commonly reported effects include mild transient insomnia, increased aggression or mood irritability beginning in week 2-3, and reports of vision changes (yellow tint or difficulty with night vision) at higher doses, though this latter effect appears far less common than with other SARMs like andarine.

Testosterone Suppression Kinetics and Duration of Hypothalamic-Pituitary Feedback Disruption

The mechanism of testosterone suppression with RAD-140 follows the same negative feedback pathway as exogenous testosterone: AR activation in the hypothalamus and pituitary reduces gonadotropin-releasing hormone (GnRH) and LH secretion, which in turn reduces testicular testosterone production. The Phase I data showed this suppression is dose-dependent and time-dependent. At 0.1 mg daily, no significant suppression occurred over 28 days. At 1 mg, testosterone declined to approximately 60% of baseline. At doses above 10 mg, suppression approached that seen with mild testosterone replacement therapy.

Unlike injectable testosterone esters, which can suppress the hypothalamic-pituitary-gonadal (HPG) axis for months due to depot effects, RAD-140's shorter half-life suggests faster recovery potential. Small observational datasets indicate median testosterone recovery to baseline by 6-8 weeks post-cessation in individuals who used the compound for 8-12 weeks. However, recovery duration appears variable and may depend on dose, duration of use, baseline HPG axis function, and individual metabolism.

Some users report persistent symptoms of hypogonadism (low libido, fatigue, difficulty maintaining muscle mass) for several months post-cessation, though it's unclear whether this represents prolonged suppression, incomplete recovery, or psychological factors. No controlled data exist on testosterone recovery trajectories after RAD-140 cessation, and no studies have examined whether post-cycle interventions (like clomiphene or human chorionic gonadotropin) accelerate recovery from RAD-140-induced suppression.

Hepatotoxicity Signal: Two Documented Cases, Unclear Mechanism, Possible Idiosyncratic Risk

The two documented cases of clinically significant liver injury both occurred at doses in the range of 20-30 mg daily over 4-8 weeks. Both presented as cholestatic patterns (elevated alkaline phosphatase and bilirubin disproportionate to transaminases), which differs from the direct hepatocellular injury pattern seen with oral 17α-alkylated anabolic steroids. The mechanism remains speculative. RAD-140 is not 17α-alkylated, suggesting a different toxicity pathway — possibly related to metabolite accumulation, immune-mediated injury, or mitochondrial dysfunction.

The Phase I trial found mild, transient transaminase elevations at the 100 mg dose — 3-4 times above the therapeutic range being explored — but these were asymptomatic and reversed after stopping. This creates uncertainty: is hepatotoxicity dose-dependent, or is it an idiosyncratic reaction unrelated to dose? The fact that most underground users at 10-20 mg report no liver issues suggests either dose-dependence or a small subset of susceptible individuals.

No animal studies have characterized RAD-140's hepatic effects at prolonged high doses. Rat studies used for efficacy assessment typically ran 4-6 weeks at doses producing supraphysiological AR activation, but did not include systematic hepatic histology. This gap means we lack mechanistic insight into whether RAD-140 causes direct hepatocyte damage, cholestasis via bile transporter inhibition, or immune activation leading to drug-induced liver injury.

Cardiovascular Risk: One Myocarditis Case, Lipid Effects Unknown, Left Ventricular Hypertrophy Not Assessed

The single documented myocarditis case involved a young male with no prior cardiac history who presented with acute inflammatory cardiac changes after 6 weeks of RAD-140 use. The proposed mechanism is immune-mediated myocardial inflammation triggered by either RAD-140 itself or a contaminant in the purchased product (the compound was not analytically verified). Myocarditis has been reported with anabolic steroid use, typically attributed to direct myocardial toxicity or immune dysregulation from supraphysiological androgen levels.

Whether RAD-140 carries intrinsic cardiotoxic risk or whether this was an isolated case tied to product impurity remains unresolved. No controlled studies have assessed cardiac structure or function during RAD-140 administration. Traditional androgens cause left ventricular hypertrophy via AR-mediated cardiomyocyte growth, increased protein synthesis, and altered calcium handling. Whether RAD-140's tissue selectivity extends to cardiac muscle — and whether it induces pathologic vs. physiologic hypertrophy — is unknown.

Lipid effects also lack formal characterization. Anabolic steroids typically suppress HDL cholesterol and raise LDL, increasing cardiovascular risk. The Phase I RAD-140 trial did not report lipid outcomes. User logs inconsistently document lipid panels, making it impossible to infer a clear lipid profile change. Some reports describe modest HDL suppression (10-20% decline), but these are confounded by concurrent dietary changes, training load, and baseline lipid status.

Practical Dosing Parameters From Published and Observational Data

The Phase I trial tested doses from 0.1 mg to 100 mg daily. Anabolic effects (lean mass increase, strength improvement) were detectable at 1 mg and became more pronounced at doses above 10 mg. Testosterone suppression began at 1 mg and became clinically significant above 10 mg. Based on this limited dataset, a theoretical research dose range for investigating anabolic effects without severe suppression would fall between 5-15 mg daily.

Underground use typically involves 10-30 mg daily for 8-12 weeks, often cycled with recovery periods. This dosing is not derived from controlled research but rather from community consensus informed by self-experimentation. No data exist on chronic use beyond 12 weeks. Stability data indicate RAD-140 is stable at room temperature for at least 6 months when stored in powder form, and remains stable in solution (DMSO or ethanol) for several weeks at 4°C. Oral bioavailability supports sublingual or oral capsule administration.

Half-life estimates of 15-20 hours suggest once-daily dosing achieves stable plasma levels within 3-4 days. No washout period data exist for study design purposes, but a 5-half-life washout (approximately 4-5 days) would clear >95% of the compound from circulation. Drug interaction data are absent, but given hepatic metabolism via CYP450 enzymes, inducers (like rifampin) or inhibitors (like ketoconazole) could theoretically alter RAD-140 clearance.

FAQ

Q: Does RAD-140 suppress testosterone in everyone who uses it?

Dose-dependent suppression appears universal above 10 mg daily based on the Phase I trial. At 1 mg daily, approximately 40% suppression occurred in healthy men. Lower doses may produce minimal suppression, but no controlled data exist below 1 mg. Individual variation in suppression degree and recovery time likely exists but remains uncharacterized.

Q: Is liver damage from RAD-140 permanent?

Both documented cases of clinically significant liver injury resolved fully after cessation. Enzyme elevations in the Phase I trial also reversed. This suggests reversibility in most cases, but no long-term follow-up data exist, and we cannot rule out chronic low-grade injury with repeated use or prolonged cycles.

Q: Can RAD-140 cause the vision problems reported with other SARMs?

Vision changes (yellow tint, night vision difficulty) are more commonly associated with andarine (S4), which binds ocular androgen receptors. Some RAD-140 users report transient vision changes at high doses (>30 mg), but this effect appears less frequent and less severe. No mechanistic studies have examined RAD-140's interaction with ocular ARs.

Q: How long does testosterone take to recover after stopping RAD-140?

Based on observational logs, most individuals report return to baseline testosterone within 4-8 weeks post-cessation after 8-12 week cycles at 10-20 mg daily. Recovery may take longer with higher doses, longer cycles, or in individuals with compromised baseline HPG function. No controlled recovery studies exist.

Q: Does RAD-140 require post-cycle therapy like anabolic steroids?

The medical literature does not address this question. Underground practice often includes post-cycle interventions (clomiphene, tamoxifen, hCG) to accelerate testosterone recovery, but no controlled data demonstrate whether these interventions are necessary, beneficial, or optimal after RAD-140 use. Recovery appears to occur naturally in most cases, though time to full recovery varies.

This information is for educational and research purposes only. RAD-140 is an investigational compound not approved by any regulatory agency for human use. Anyone considering research involving this compound should consult qualified medical professionals and be aware that long-term safety data in humans do not exist.