LGD-4033

LGD-4033 was developed in the early 2000s by Ligand Pharmaceuticals and later licensed to Viking Therapeutics, where it is being developed as VK5211 for hip fracture recovery. Unlike many research chemicals, LGD-4033 has undergone multiple Phase 1 and Phase 2 clinical trials in humans, providing a foundation of controlled safety and efficacy data that most SARMs lack. A landmark Phase 1 trial published in the Journal of Gerontology (Basaria et al., 2013) demonstrated significant lean mass gains (approximately 1.21 kg over 21 days at 1 mg/day) with a dose-dependent increase in lean body mass across doses up to 1 mg/day — far below the 5–10 mg doses used in the research chemical community. This trial also documented the dose-dependent testosterone suppression that has become LGD-4033's most significant documented adverse effect. LGD-4033's position as the most mass-effective SARM makes it a common first choice for users seeking steroid-like gains from an oral, non-injectable compound. This popularity has made it the most commonly implicated SARM in athlete doping violations.

Lean mass gains at doses used in the research community (5–10 mg/day) are substantially greater than those seen in clinical trials (0.3–1 mg/day), with anecdotal reports consistently describing 5–10 lbs of lean mass gains in a 6–8 week cycle. These gains occur without the water retention associated with testosterone, producing a cleaner, more aesthetic physique change. Bone density improvement is documented in clinical data. LGD-4033's androgen receptor activity in bone tissue makes it relevant for osteoporosis research, and this bone support is a meaningful secondary benefit for athletes under high mechanical load. No estrogen conversion eliminates gynecomastia and water retention risks. Unlike testosterone, LGD-4033 does not aromatize, allowing lean mass accumulation without the bloat management that wet compounds require. Strength gains — while primary driven by the lean mass increase — are also reported independently, possibly through direct AR-mediated effects on neuromuscular drive.

Testosterone suppression is dose-dependent and well documented in clinical trials. Even at 1 mg/day (significantly below typical research community doses), total and free testosterone were meaningfully suppressed at 21 days. At 5–10 mg/day, suppression is more profound and recovery after cessation takes longer. HDL cholesterol reduction is consistent across clinical data. LGD-4033 reliably lowers HDL, worsening the cardiovascular risk profile in proportion to dose and duration. Liver enzyme elevations have been reported in some users at higher doses, though LGD-4033 is not 17-alpha alkylated and its direct hepatotoxicity mechanism differs from oral steroids. Rare but serious hepatotoxicity cases have been published as case reports. Athlete contamination sensitivity: LGD-4033 has caused several high-profile athlete doping violations, including cases where trace contamination of other supplements was the alleged source. The compound's potency means nanogram-level exposure can produce detectable metabolites.

Conservative start: 2–5 mg/day for beginners or conservative users. Clinical trials showed meaningful effects at 1 mg/day; the research community uses higher doses but the dose-response for side effects also scales. Standard performance dose: 5–10 mg/day. Most anecdotal reports and research community consensus settle on 5–7.5 mg/day as the optimal balance of efficacy and suppression management. Cycle length: 6–8 weeks. LGD-4033's 24–36 hour half-life means once-daily dosing provides stable levels. Cycles beyond 8 weeks substantially increase suppression severity and extend recovery time. PCT: Required. Nolvadex 20–40 mg/day for 4–6 weeks is standard. Suppression from LGD-4033 can be more severe than from milder SARMs; some practitioners add Clomid for the first 2 weeks of PCT if bloodwork shows very low LH/FSH.

United States: Research chemical status — not controlled, not FDA approved. The FDA has issued warning letters to vendors making drug claims about LGD-4033 and has named it in enforcement actions targeting the SARM market. United Kingdom: The MHRA has regulated SARMs, and LGD-4033 importation for supply is illegal. Personal importation for research exists in a gray zone. WADA: Explicitly prohibited. LGD-4033 is one of the most commonly detected SARMs in athletic anti-doping testing. Detection windows extend to weeks after cessation. Multiple high-profile athlete suspensions have involved LGD-4033.

LGD-4033 + MK-677: A popular clean-bulk stack. LGD-4033 drives lean mass gains; MK-677 adds GH/IGF-1 elevation, sleep improvement, and appetite stimulation to support caloric surplus and recovery. LGD-4033 + Cardarine (if risk accepted): Adding Cardarine's endurance enhancement to LGD-4033's mass gains addresses the performance drop that can come from training in a caloric surplus. Note Cardarine's serious carcinogenicity concerns. LGD-4033 alone: Many users prefer LGD-4033 solo to isolate its effects and minimize combined suppression risk. This is the recommended approach for first-time SARM users who choose LGD-4033.

LGD-4033 — Common Questions