RAD-140

RAD-140 was originally developed by Radius Health as a potential treatment for muscle wasting, osteoporosis, and breast cancer, leveraging its potent androgen receptor (AR) agonism in selective tissues. Its binding affinity for the androgen receptor is exceptionally high — comparable to testosterone — but its tissue selectivity distinguishes it from testosterone, which activates ARs throughout the body including in the prostate. The compound's long half-life (~60 hours) distinguishes it from most other SARMs and means that once-daily dosing produces stable blood levels, though it also means that if side effects occur, they persist longer after discontinuation. This extended half-life is both a practical convenience and a risk consideration. Human clinical trial data for RAD-140 is limited — phase 1 and early phase 2 trial data exist for specific oncology indications, but comprehensive safety and efficacy data in healthy subjects is absent. Most of what is known about RAD-140 in healthy, performance-oriented individuals comes from animal studies and extensive anecdotal human use.

Muscle and strength gains of a magnitude closer to anabolic steroids than to other SARMs are RAD-140's primary performance characteristic. Anecdotally and in limited human data, RAD-140 produces lean mass gains and strength improvements that substantially exceed those of milder SARMs like Ostarine, making it the preferred SARM for users with serious performance goals. Tissue selectivity — the theoretical advantage of SARMs over traditional anabolic steroids — means RAD-140 is designed to activate androgen receptors in muscle and bone without triggering androgenic activity in the prostate or scalp. In animal studies, this selectivity has been demonstrated; in humans, the clinical picture is less clear. Neuroprotective properties have been documented in cell culture and animal studies. RAD-140 activates brain androgen receptors in ways that appear to protect neurons from amyloid-beta toxicity — the hallmark of Alzheimer's pathology. While this is far from a basis for clinical use, it is a noted distinction in the SARM literature. No estrogen conversion means no gynecomastia, water retention, or estrogen-related mood effects at any dose — a significant practical advantage over testosterone.

Testosterone suppression is the most significant and reliable adverse effect. Unlike testosterone, which is self-amplifying, RAD-140 suppresses the HPTA through androgen receptor-mediated negative feedback without replacing the testosterone it suppresses. Total testosterone can be reduced significantly (>50–70%) at doses of 15–20 mg/day, producing low-T symptoms including reduced libido, fatigue, and mood disruption. Liver enzyme elevation has been reported in both human trials and anecdotal use. Transaminase elevations (AST, ALT) occur at higher doses and with longer cycles. In most documented cases these normalize after discontinuation, but cases of more significant hepatotoxicity have been reported in the medical literature with RAD-140 specifically. Aggression and mood changes — particularly increased irritability — are commonly reported, consistent with potent androgen receptor activation. These effects are dose-dependent. Hair shedding in individuals with androgenic alopecia sensitivity is reported despite RAD-140's theoretical DHT-independence, suggesting that high-affinity AR agonism may accelerate hair loss through direct follicle AR activity even without DHT conversion.

Conservative starting dose: 5–10 mg/day for the first 1–2 weeks to assess individual response, particularly regarding suppression and mood effects. Standard performance dose: 10–20 mg/day. The dose-response curve is meaningful in this range; many users find 15 mg produces excellent results with manageable suppression, while 20 mg increases both gains and side effects. Cycle length: 6–8 weeks is the standard recommendation, with some advanced users extending to 10–12 weeks with bloodwork monitoring. RAD-140's long half-life means recovery after a cycle is slower than with shorter-acting SARMs. PCT: Post-cycle therapy is required. A standard SERM-based PCT (Nolvadex 20–40 mg/day for 4–6 weeks) is the minimum; more aggressive suppression may warrant Clomid addition. Bloodwork: Pre-cycle testosterone baseline and post-cycle testosterone + LH/FSH monitoring are strongly recommended to assess suppression severity and guide PCT duration.

United States: RAD-140 is not FDA approved and not a controlled substance. Legal to purchase as a research chemical. Subject to the same FDA enforcement environment as other SARMs, including potential warning letters to vendors. SARMs Control Act: Proposed legislation to schedule SARMs as controlled substances has been introduced in the US Congress multiple times but has not been enacted as of current knowledge. This status could change. WADA / Sports: Explicitly prohibited. RAD-140 is testable in standard anti-doping panels used by WADA-affiliated sports. Detection windows extend significantly beyond the active use period given the 60-hour half-life and slow metabolite clearance.

RAD-140 + MK-677: A popular combination addressing two complementary anabolic pathways — direct androgen receptor activation (RAD-140) and GH/IGF-1 axis elevation (MK-677). MK-677's recovery, sleep, and connective tissue benefits complement RAD-140's direct anabolic activity. RAD-140 + LGD-4033: A potent mass-building stack. Both are high-affinity SARMs with meaningful suppression risk; combined, they produce significant gains but also significant HPTA suppression. Not recommended for beginners. RAD-140 as a testosterone base replacement: Some users run RAD-140 during the bridging period between steroid cycles to maintain gains while allowing partial HPTA recovery — though this is controversial and RAD-140's own suppression makes true HPTA recovery difficult during active use.

RAD-140 — Common Questions