LGD-4033 vs Naltrexone
Moderate Research vs FDA Approved
avoid Mechanism-based · 64% Both LGD-4033 and Naltrexone carry hepatotoxic risk. Combining hepatotoxic compounds significantly increases liver damage potential. If unavoidable, include liver support (TUDCA/NAC) and monitor ALT/AST frequently.
Molecular Data
LGD-4033 Naltrexone
Weight 338.25 Da 341.40 Da
Half-life ~24-36 hours ~4 hours
Type Nonsteroidal selective androgen receptor modulator (C14H12F6N2O) Opioid antagonist (C20H23NO4)
Key Benefits
LGD-4033
01 Strongest SARM for lean muscle mass accrual, with clinical trial data supporting dose-dependent increases in lean body mass
02 Tissue-selective action with minimal stimulation of the prostate and other androgen-sensitive tissues
03 Clinical evidence of improved physical function (leg press strength, stair-climbing speed) in hip fracture patients
04 No aromatization to estrogen (no estrogen-related water retention or gynecomastia at the receptor level)
05 No conversion to DHT (reduced risk of androgenic hair loss and prostate stimulation compared to testosterone)
06 Convenient once-daily oral dosing due to 24-36 hour half-life
07 Phase 2 clinical data available, providing a stronger evidence base than most other SARMs
Naltrexone
01 Broad anti-inflammatory and immunomodulatory effects via OGF-OGFr axis upregulation
02 Reduction in pro-inflammatory cytokines (TNF-alpha, IL-6, IL-12) through TLR4 antagonism
03 Compensatory upregulation of endogenous endorphins and enkephalins (200-300% increase)
04 Improved immune regulation and rebalancing of Th1/Th2/Th17 responses
05 Reduction in chronic pain through central and peripheral opioid system modulation
06 Potential improvement in mood, anhedonia, and overall well-being via endorphin enhancement
07 Extremely well-tolerated with minimal side effects at low doses
08 Low cost, especially as compounded LDN formulation
Side Effects
LGD-4033
Testosterone suppression (dose-dependent; more suppressive than Ostarine at equivalent doses, occurs in most users by week 4-6)
Water retention (non-estrogenic mechanism, typically mild to moderate, contributes to scale weight increase)
HDL cholesterol reduction (dose-dependent lipid impact observed in clinical trials)
Headaches (most common in the first 1-2 weeks, usually transient)
Fatigue or lethargy (related to testosterone suppression, typically becomes noticeable mid-cycle)
Reduced libido (related to HPG axis suppression, severity varies by dose and individual)
Naltrexone
Vivid dreams or unusually intense dreaming - the most frequently reported side effect, typically diminishes over 1-2 weeks
Initial sleep disruption or insomnia during the first week of treatment
Mild nausea, particularly during the first few days
Transient headache during dose initiation or titration
Contraindications
Pre-existing liver disease or elevated liver enzymes at baseline
Hormone-sensitive cancers (prostate cancer or other androgen-driven malignancies)
Pregnancy or potential pregnancy (teratogenic risk from androgen receptor agonism)
Breastfeeding
Age under 25 (incomplete endocrine system maturation and higher risk of HPG axis disruption)
Concurrent use of hepatotoxic medications without medical supervision
Known cardiovascular disease (insufficient long-term safety data for this population)
History of significant lipid abnormalities (LGD-4033 suppresses HDL)
Current use of opioid medications or active opioid dependence (must be opioid-free 7-10 days minimum)
Acute hepatitis or severe hepatic impairment (primarily relevant at full dose)
Known hypersensitivity to naltrexone
Anticipated need for opioid pain medication (e.g., upcoming surgery - discontinue LDN 3-7 days prior)
Research Evidence
LGD-4033 Naltrexone
Status Moderate Research FDA Approved
References 5 studies 5 studies
Latest 2018 2023
FDA Approved No Yes
This comparison is for educational and research purposes only. Consult a healthcare professional before use.