Fluoxymesterone vs Testosterone Undecanoate
A side-by-side research comparison of Fluoxymesterone and Testosterone Undecanoate across mechanism, dosing, half-life, benefits, side effects and research status.
Comparison table
| Attribute | Fluoxymesterone | Testosterone Undecanoate |
|---|---|---|
| Full name | Fluoxymesterone (Halotestin) | Testosterone Undecanoate (Ultra-Long Ester) |
| Category | Anabolic Steroids | Anabolic Steroids |
| Status | FDA-approved drug (controlled substance) | FDA-approved drug (controlled substance) |
| Mechanism | A 17-alpha-alkylated, fluorinated derivative of methyltestosterone with extremely high androgenic potency. It boosts strength, aggression, and red blood cells rapidly but does little for muscle size. | The large undecanoate ester dramatically slows release, giving weeks-long duration from a single injection. Oral undecanoate is absorbed via the lymphatic system, partly bypassing first-pass liver metabolism. |
| Molecular weight | 336.4 Da | 456.7 Da |
| Half-life | ~9 hours | ~20-34 days (injection depot) |
| Bioavailability | Oral | Deep IM injection or oral (lymphatic absorption) |
| Typical dose | Medical: ~2.5-20 mg/day | Injection every ~10-14 weeks (medical); oral 2x daily with food |
| Frequency | Daily | Infrequent (injection) or twice daily (oral) |
| Route | Oral tablet | Deep intramuscular injection or oral |
Fluoxymesterone reported benefits
- Rapid strength gains
- Increased aggression/drive
- Red blood cell stimulation
- No added water weight
Testosterone Undecanoate reported benefits
- Very infrequent injections (convenience)
- Stable long-term testosterone (medical)
- Oral option avoids most liver toxicity
- Restores testosterone in deficiency
Related comparisons
Research and educational reference only. Not medical advice.