Testosterone Undecanoate
Testosterone undecanoate is a long-chain ester hydrolyzed to free testosterone after deep intramuscular injection into the gluteal muscle, providing sustained release over weeks. Free testosterone activates the androgen receptor in target tissues, modulating transcription of genes that maintain male secondary sexual characteristics, skeletal muscle mass, bone density, and erythropoiesis. The injectable castor oil/benzyl benzoate vehicle contributes to the slow-release kinetics and is responsible for the risk of POME if inadvertently administered intravascularly.
Injectable esters release over days to weeks depending on the ester; oral agents act within hours. Hormonal effects accrue over weeks, and dosing is individualized by a clinician.
Oil-based injectable (castor oil/benzyl benzoate vehicle); store at controlled room temperature (20-25 degrees C). Protect from light. Do not refrigerate or freeze.
Clinical Evidence
What the literature says
Pharmacokinetics
- Routes
- Intramuscular
Citations (3)
Last reviewed: 2026-06-15
Research Guide
How users approach this compound
The following reflects patterns observed in research literature and community protocols. This is not medical advice and does not constitute a clinical recommendation.
Reported Uses
- FDA-approved testosterone replacement in adult males with primary hypogonadism
- FDA-approved testosterone replacement in adult males with hypogonadotropic hypogonadism
Key Research Benefits
- Long dosing interval (injections every 10 weeks after loading, per Aveed label) due to the long undecanoate ester
- Restoration of androgen levels in adult males diagnosed with hypogonadism per FDA-approved indications
Potential Side Effects
Considerations and Cautions
- Known or suspected prostate carcinoma or breast carcinoma in males
- Hypersensitivity to testosterone, castor oil, or benzyl benzoate
- Women who are pregnant or may become pregnant
- Administration outside a REMS-enrolled healthcare facility is contraindicated for Aveed
Labs to monitor
Educational context only, not a testing mandate. Any bloodwork decisions belong with your clinician.
- Hematocrit / hemoglobin: Erythrocytosis risk; monitoring per label required.
- Estradiol (E2): Aromatization to estradiol; elevated E2 associated with gynecomastia.
- PSA (prostate-specific antigen): Prostate surveillance per standard androgen therapy protocol.
- Lipid panel: Testosterone therapy can adversely affect lipid profile.
- Total testosterone / free testosterone: Trough monitoring confirms therapeutic levels before next injection.
Dose Calculator
Peptide Reconstitution Calculator
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Testosterone Undecanoate by goal
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Not medical advice
Information on DoseVault is for educational purposes only and is not a substitute for medical advice, diagnosis, or treatment from a qualified healthcare provider.