Testosterone undecanoate
A long-acting testosterone ester, given as an intramuscular depot or an oral capsule, for confirmed male hypogonadism.
Medications & hormones
Research records
Historical source snapshot. Not freshly verified, not a recommendation. Study findings, community accounts and app defaults are not interchangeable.
Publication suitability · 2026-10-15: Historical reference only; not a clinical verification. Clinical, regulatory, efficacy, safety and dose claims are not independently established by this review.
Testosterone undecanoate
A long-acting testosterone ester, given as an intramuscular depot or an oral capsule, for confirmed male hypogonadism.
Evidence category: Regulator / guideline. This describes the source category, not approval or certainty.
Regulatory statement in source: EMA-approved (depot injection) and FDA-approved (oral capsule), as separate formulations.
Testosterone undecanoate is a long-acting ester of testosterone, delivered either as an intramuscular depot injection or as an oral capsule formulated for lymphatic absorption. It is approved in the European Union as an injectable depot for male hypogonadism and in the United States as an oral capsule for the same indication, with regulatory review covering pharmacokinetics, cardiovascular safety, and hepatic effects in adult men with confirmed testosterone deficiency.
Benefits reported in the imported source
- Regulatory-reviewed option for restoring serum testosterone to the normal range in men with confirmed hypogonadism.
- Available in both a long-acting intramuscular depot form and an oral capsule form, reviewed by the EMA and FDA respectively.
- Extensive postmarketing history as one of the original approved testosterone replacement therapies, first approved in the 1950s.
Risks and limits
- FDA labeling carries a boxed warning for increases in blood pressure with the oral capsule form.
- Depot injection formulations have been associated with rare pulmonary oil microembolism reactions at the time of injection.
- Long-term cardiovascular and prostate safety in men without confirmed hypogonadism has not been established in either label.
Source bottom line: Testosterone undecanoate is a regulator-approved testosterone replacement therapy for men with confirmed hypogonadism, with distinct EU depot-injection and US oral-capsule labels covering different regimens and monitoring requirements.
Uncertainty: Reference information only. Not medical advice.
Study protocols — reports, not instructions
adult men with hypogonadism confirmed by clinical features and biochemical testing
- Reported regimen
- 1000 mg testosterone undecanoate given by deep intramuscular injection, with the interval between the first two injections shortened to six weeks and every injection thereafter spaced ten to fourteen weeks apart
- Duration
- ongoing replacement therapy, dosed every ten to fourteen weeks after the initial loading interval
- Reported outcome
- European regulatory labeling establishing testosterone undecanoate depot injection as a testosterone replacement therapy that restores serum testosterone to the normal range in hypogonadal men
- Source
- Nebido 1000 mg/4 ml Summary of Product Characteristics (EMC/UK)
Claim provenance
evidence.json#/catalog:hormone:testosterone-undecanoate/protocols/0
adult men with primary hypogonadism or hypogonadotropic hypogonadism confirmed by low morning serum testosterone on two separate days; not established for age-related hypogonadism
- Reported regimen
- oral capsules taken twice daily with food, at a labeled starting dosage of 237 mg in the morning and 237 mg in the evening, titrated between 158 mg and 396 mg twice daily based on serum testosterone measured six hours after the morning dose
- Duration
- dose adjustment assessed at least seven days after initiation or any dosage change, with periodic monitoring thereafter
- Reported outcome
- FDA-approved oral testosterone replacement shown in labeling trials to raise serum testosterone into the normal range in hypogonadal men, carrying a boxed warning for blood pressure increase
- Source
- JATENZO (testosterone undecanoate) capsule label — DailyMed
Claim provenance
evidence.json#/catalog:hormone:testosterone-undecanoate/protocols/1
Community and practice descriptions
Accounts of a practice are not evidence of safety or effectiveness. Words such as “standard”, “safe” or “recommended” describe the source account, not verified consensus or this wiki’s advice. Commercial and self-published citations are retained for traceability, not vendor endorsement or independent clinical corroboration.
Unverified imported account — Microdosing TRT – The Future of Testosterone Replacement Therapy - The Men's Health Clinic
An imported authored paraphrase, not a quotation or a recommended protocol.
Review: unverified historical account. The imported wording is preserved for attribution; its full clinical, dosing, efficacy or consensus claims have not been independently established. Unvalidated source account; no validated human dosing population or animal-to-human equivalence is inferred.
Imported wording: A clinical TRT reference documents a standard testosterone undecanoate protocol of 1000 mg given initially, followed by a second 1000 mg dose at six weeks, then 1000 mg maintenance injections administered every 10–12 weeks based on blood work.
Microdosing TRT – The Future of Testosterone Replacement Therapy - The Men's Health Clinic
Unverified imported account — Microdosing TRT – The Future of Testosterone Replacement Therapy - The Men's Health Clinic
An imported authored paraphrase, not a quotation or a recommended protocol.
Review: unverified historical account. The imported wording is preserved for attribution; its full clinical, dosing, efficacy or consensus claims have not been independently established. Unvalidated source account; no validated human dosing population or animal-to-human equivalence is inferred.
Imported wording: The same source documents an alternative protocol of 125 mg testosterone undecanoate administered via deep intramuscular injection weekly to maintain more consistent testosterone levels throughout treatment cycles.
Microdosing TRT – The Future of Testosterone Replacement Therapy - The Men's Health Clinic
Pharmacokinetic context
Historical half-life estimate: 501.6–813.6 hours. Nieschlag & Behre, Andrology (Springer, 2010) pp.441-446; Saad et al. 2007, Asian J Androl, PMID 17486268 — range reflects tea-seed-oil vs castor-oil vehicle Population/route context and estimates may differ. This is not a schedule or a verified human dosing rule.
Source references
- Nebido 1000 mg/4 ml Summary of Product Characteristics (EMC/UK)
- JATENZO (testosterone undecanoate) capsule label — DailyMed
Snapshot provenance
Source ID: catalog:hormone:testosterone-undecanoate. Commit: adc7684614f9439b41d91a3312b62e7982c7e20e. Review state: historical-not-reverified. Authored links are retained separately from the canonical evidence links in the public data. App templates/defaults and rejected drafts are archived, not deployed.
Related entries and components
None listed.