Not FDA-approved for human use. WADA-banned for tested athletes. Sold as a research chemical; clinical safety beyond short-term trials is not established. This page is educational reference only, not a recommendation or endorsement of use.
- Half-life
- 29 h
- Route
- Oral
Summary
LGD-4033 is a non-steroidal selective androgen receptor modulator with high binding affinity at the androgen receptor. Originally developed for age-related muscle loss, osteoporosis, and post-hip-fracture recovery. Has Phase II clinical trial data in healthy young men showing dose-dependent lean mass gains.
It is orally bioavailable and does not aromatize to estrogen. Suppression of endogenous testosterone was measurable in those trials and is substantial at the exposures reported outside them.
Legal status: Not FDA-approved. WADA-prohibited at all times in competitive sport. Sold as a research chemical outside of approved channels. The compound with the most positive doping tests among athletes — multiple high-profile cases have been documented, often via "contaminated supplements," sometimes via direct use.
Main effects
- Lean mass accretion, dose-dependent in the Phase II trial data
- Strength gains comparable to RAD-140
- Improved nitrogen retention
- Some water retention (more than other SARMs, less than testosterone)
- Improved recovery between training sessions
Common side effects
- HPTA suppression — substantial. At 1 mg/day in clinical trials, total testosterone dropped ~50%; at the higher exposures common in non-medical use, suppression of 60–80% is typical and reliable.
- Lipid changes — moderate HDL reduction (20–35%), some LDL elevation.
- Hepatic enzymes — ALT/AST elevations possible but typically less severe than oral AAS. Reversible.
- Estradiol shifts — can rise modestly via SHBG suppression.
- Water retention — more than other SARMs. Some users report a fuller, less dry look.
- Mood — generally well-tolerated. Some users report mild aggression.
- WADA-banned — most positive doping tests of any SARM. Detection window 2–3 weeks.
Mechanism
High-affinity, full agonist at the androgen receptor in muscle and bone. Strong tissue selectivity — minimal impact on prostate or skin androgen receptors at therapeutic exposures.
Anabolic-to-androgenic ratio in animal models: approximately 10:1, with higher absolute potency than Ostarine.
Pharmacokinetics
- Half-life: ~24–36 hours
- Tmax (oral): 1–2 hours
- Bioavailability (oral): high
- Metabolism: hepatic
- Elimination: urinary
Bloodwork monitoring
Standard panel coverage seen in the Phase II trial protocols and harm-reduction discussions:
- Total + Free Testosterone
- LH, FSH
- Estradiol (sensitive assay)
- SHBG
- Full lipid panel
- ALT, AST, GGT
- CBC
Interactions
LGD-4033 acts at the same receptor as testosterone and other androgen receptor agonists, so suppression of LH and FSH reflects total androgenic signaling rather than any single agent. It is cleared hepatically, so liver enzyme elevation seen alongside other hepatically metabolized compounds cannot be attributed to one of them.
Pharmacokinetic modeling parameters
ka: 1.5 /day
ke: 0.58 /day
Vd: 50 L
F: 0.85
half_life_hours: 29
Notes and caveats
- The compound with the most positive doping tests among athletes — multiple high-profile athletes have tested positive, often via "contaminated supplements," sometimes via direct use.
- Phase I data showed safety and tolerability at sub-mg exposures; non-medical exposures are substantially higher with correspondingly amplified side effects.
- Viking Therapeutics continues developing the compound (as VK5211) for hip-fracture recovery — one of the few SARMs with active pharmaceutical development.