hormoneInjectableControlledSchedule III (US, Anabolic Steroids Control Act)Prescription only (US)FDA-approved both as an oral capsule (e.g., Jatenzo) and as a long-acting injectable (e.g., Aveed) for testosterone deficiency due to hypogonadismInjectable long-acting undecanoate carries an FDA boxed warning for post-injection pulmonary oil microembolism and anaphylaxis, requiring in-office observation after dosing
Testosterone UndecanoateBenefits, Dosage & Interactions
Also known as: Nebido, Aveed, Andriol
Testosterone undecanoate is an esterified form of the androgen testosterone, primarily used in testosterone replacement therapy (TRT) for men with clinical hypogonadism. Research on Testosterone Undecanoate focuses on testosterone support, cognition and mood, and libido. Testosterone Undecanoate is administered by injection rather than orally.
Researched by DoseRoutine R&D TeamReviewed for accuracy by Nicholas Alexander, RSELast updated
Evidence: Limited — Human observational or case data only — no randomized trials.
Evidence strengthLimited · 2/4
PreclinicalStrong human evidence
Human observational or case data only — no randomized trials.
Plasma half-life
Reported as substantially longer than enanthate, supporting the extended dosing interval described in the pharmacokinetic comparison
Default unit
mg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
- Reported amounts
- Parenteral long-acting testosterone undecanoate is dosed at 1000 mg per injection in the post-marketing surveillance cohort; the pharmacokinetic comparison used single 1000 mg doses[1][2][3]
- Route studied
- Deep intramuscular injection (long-acting depot) in the cited human studies; oral capsules are a separate FDA-approved formulation[1][2][3]
Reported for Testosterone Undecanoate in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the Testosterone Undecanoate entry is written from. Each number matches an inline marker above.
- [1]Injectable testosterone undecanoate has more favourable pharmacokinetics and pharmacodynamics than testosterone enanthatePartsch CJ, Weinbauer GF, Fang R, Nieschlag E · European Journal of Endocrinology · 1995 · Peer-reviewed · PMID 7711892
- [2]Recovery of male reproductive endocrine function after ceasing prolonged testosterone undecanoate injectionsHandelsman DJ, Desai R, Conway AJ, Bathur F, Jayadev V, Zamojska A, McLachlan RI · European Journal of Endocrinology · 2022 · Peer-reviewed · PMID 35000898
- [3]Effectiveness and tolerability of parenteral testosterone undecanoate: a post-marketing surveillance studyWolf J, Nelson NA, Zitzmann M · The Aging Male · 2017 · Peer-reviewed · PMID 28812471
- [4]Testosterone undecanoate in the treatment of male hypogonadismEdelstein D, Dobs A, Basaria S · Expert Opinion on Pharmacotherapy · 2010 · Peer-reviewed · PMID 20642374
How to track Testosterone Undecanoate doses
Testosterone Undecanoate is tracked as a protocol rather than a single reminder: a vial with a concentration, a schedule that may be titrated or cycled, and a rotation of injection sites. Here is the record that keeps all three consistent.
- 1
Record the vial and concentration
Log the vial strength and the volume of bacteriostatic water you added so Testosterone Undecanoate is stored as a concentration rather than a guess. DoseRoutine converts that into mg per syringe unit and counts the doses left in the vial as you log.
- 2
Set the schedule, not just a reminder
Enter the dose in mg and the frequency. Cycled protocols get a start and end date so the history stays accurate when Testosterone Undecanoate comes out of the routine.
- 3
Rotate and log the injection site
Pick the site at the moment you log the dose. The site map shows what you used last and how recently, which is the part that drifts fastest when two compounds run on different frequencies.
- 4
Log adherence, not intentions
Mark each dose taken, skipped or delayed as it happens. Weeks of honest logs are what make an adherence rate or a trend line meaningful; retrospective guessing is not.
- 5
Review against outcomes
Review Testosterone Undecanoate alongside your logged metrics and any relevant blood work every few weeks before changing the dose, so the change is a response to data rather than to a good or bad day.
What to log each time
- Dose in mg and the syringe units it worked out to
- Vial: reconstitution date, concentration, doses remaining
- Injection site and time
- Any side effects in the 24 h after the dose
References & Evidence
Sources on this page that document Testosterone Undecanoate dosing, timing and safety.
- [1]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is Testosterone Undecanoate studied for?
What is Testosterone Undecanoate?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
Testosterone undecanoate is an esterified form of the androgen testosterone, primarily used in testosterone replacement therapy (TRT) for men with clinical hypogonadism. This condition is characterized by deficient testosterone production, leading to various signs and symptoms such as decreased libido, erectile dysfunction, fatigue, and loss of muscle mass. Unlike other testosterone esters, testosterone undecanoate has a very long half-life, which allows for extended intervals between doses when administered via intramuscular injection. It is also available in an oral formulation, though this form has different pharmacokinetic properties and clinical applications.
The undecanoate ester is cleaved in the body to release free testosterone, which then acts on androgen receptors to exert its physiological effects. These effects include the maintenance of bone density, red blood cell production, muscle mass and strength, fat distribution, and libido. The use of testosterone undecanoate aims to restore physiological testosterone levels, thereby alleviating the symptoms of hypogonadism and improving overall quality of life. As a controlled substance in many regions, its use is strictly regulated and requires medical supervision. (Source: DrugBank, MedlinePlus)
What does the research say about Testosterone Undecanoate?
Tap a section to expand.
Testosterone undecanoate itself is a prodrug; it is an ester of testosterone and undecanoic acid. After administration, whether orally or via intramuscular injection, the undecanoate ester is hydrolyzed by esterases in the body, releasing active testosterone. Once released, testosterone, a steroid hormone, acts primarily by binding to and activating androgen receptors (ARs) located in target tissues throughout the body, including muscle, bone, prostate, and brain.
Upon binding, the testosterone-androgen receptor complex translocates to the nucleus of the cell. In the nucleus, it interacts with specific DNA sequences called androgen response elements (AREs), which are located near target genes. This interaction modulates gene transcription, leading to the synthesis of specific proteins responsible for androgenic effects. These effects include the development and maintenance of male secondary sexual characteristics, promotion of protein anabolism (muscle growth), erythropoiesis (red blood cell production), bone density maintenance, and regulation of libido and mood. Testosterone can also be metabolized by the enzyme 5-alpha-reductase to dihydrotestosterone (DHT), a more potent androgen, or by aromatase to estradiol, an estrogen, both of which also exert biological effects. The long undecanoate chain significantly extends the half-life of testosterone in the body, primarily by rendering it more lipophilic, allowing for slow release from muscle depots after injection. (Source: DrugBank, PubChem)
Source for this section: Sources for How does Testosterone Undecanoate work?: Jumps to this entry in the sources and references list at the end of the page.
Testosterone undecanoate is primarily used to address the symptoms associated with male hypogonadism, which is a condition where the body does not produce enough testosterone. The benefits of restoring testosterone levels to a physiological range in hypogonadal men have been documented in various clinical studies:
* **Improved Sexual Function:** One of the most frequently reported benefits is an improvement in libido, erectile function, and overall sexual satisfaction. (Source: NIH ODS)
* **Increased Muscle Mass and Strength:** Testosterone plays a crucial role in protein synthesis. Restoration of testosterone can lead to increases in lean body mass and improvements in muscle strength. (Source: Cochrane Review)
* **Bone Density:** Testosterone contributes to bone mineral density. Treatment can help to prevent or reverse bone loss associated with hypogonadism, reducing the risk of osteoporosis and fractures. (Source: MedlinePlus)
* **Mood and Cognition:** Some men with hypogonadism experience improvements in mood, decreased irritability, and enhanced cognitive function, though these effects can be more varied among individuals. (Source: Mayo Clinic)
* **Reduced Fatigue and Increased Energy:** Addressing low testosterone can alleviate chronic fatigue and increase overall energy levels and vitality. (Source: NIH ODS)
* **Body Composition:** Beyond muscle mass, testosterone replacement can aid in reducing fat mass, particularly visceral fat, which is associated with metabolic health. (Source: Examine.com)
* **Erythropoiesis:** Testosterone promotes red blood cell production, which can be beneficial for men with anemia associated with hypogonadism. (Source: DrugBank)
These benefits are typically observed when testosterone levels are normalized in individuals who have a diagnosed testosterone deficiency. The extent and onset of benefits can vary widely among individuals.
Evidence supporting the efficacy of testosterone undecanoate largely stems from clinical trials investigating its use in men with diagnosed hypogonadism. Studies have consistently demonstrated its ability to elevate and maintain serum testosterone concentrations within the physiological range for extended periods after intramuscular injection, typically lasting several weeks to months. The long-acting injectable formulation, such as Nebido or Aveed, has been shown to provide stable testosterone levels with fewer peaks and troughs compared to shorter-acting esters or oral preparations.
For instance, a meta-analysis published in a reputable medical journal evaluated the effectiveness of various testosterone replacement therapies, including testosterone undecanoate, finding significant improvements in sexual function, mood, and body composition parameters in men with hypogonadism. Researchers often focus on outcomes like changes in bone mineral density, lean body mass, fat mass, and patient-reported symptoms (e.g., libido, energy levels). The oral formulation of testosterone undecanoate (e.g., Andriol) has been studied for its ability to avoid first-pass metabolism by being absorbed via the lymphatic system, though its bioavailability and consistency can be more variable compared to injectable forms. Comparative studies have often assessed its safety profile and effectiveness against other testosterone esters like testosterone enanthate or cypionate, noting its prolonged duration of action as a key distinguishing feature. (Source: Cochrane Review, FDA label, EMA SmPC)
As with any hormonal treatment, testosterone undecanoate can cause a range of side effects. These can vary in severity and depend on individual sensitivity, dosage, and duration of use. Common side effects often mirror those associated with elevated or fluctuating testosterone levels in general:
* **Erythrocytosis:** An increase in red blood cell count (hematocrit), which can increase the risk of blood clots. Regular monitoring is essential.
* **Acne and Oily Skin:** Androgenic effects can stimulate sebaceous gland activity.
* **Fluid Retention (Edema):** Swelling in ankles or feet due to water retention.
* **Increased Prostate Specific Antigen (PSA):** Testosterone can affect prostate size and PSA levels. Regular prostate monitoring is recommended, especially in older men.
* **Gynecomastia:** Development or enlargement of breast tissue, often due to conversion of testosterone to estrogen.
* **Mood Swings and Irritability:** Hormonal fluctuations can impact mood.
* **Headache:** A common non-specific side effect.
* **Sleep Apnea:** Worsening or new onset of sleep apnea.
* **Injection Site Reactions:** Pain, bruising, or irritation at the site of intramuscular injection.
* **Hair Loss:** Androgenic alopecia (male pattern baldness) can be accelerated in predisposed individuals.
* **Liver Enzyme Elevations:** Particularly with oral formulations, due to different metabolic pathways.
Less common but more serious side effects include severe allergic reactions, cardiovascular events (e.g., heart attack, stroke), and benign prostatic hyperplasia. Any unexpected or severe symptoms should prompt immediate medical attention. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Several important warnings and precautions are associated with the use of testosterone undecanoate, particularly due to its hormonal nature and potential systemic effects:
* **Cardiovascular Risk:** Increased risk of cardiovascular events, including heart attack, stroke, and venous thromboembolism (blood clots). Patients with pre-existing cardiovascular disease or risk factors should be carefully evaluated and monitored. (Source: FDA label)
* **Prostate Health:** Testosterone can stimulate the growth of prostate tissue. It is contraindicated in men with known or suspected prostate cancer or breast cancer. Regular prostate exams and PSA monitoring are critical, especially in older men. (Source: MedlinePlus)
* **Erythrocytosis:** Significant increases in hematocrit (red blood cell count) can occur, increasing the risk of thrombotic events. Hematocrit levels must be regularly monitored, and dose adjustments or phlebotomy may be necessary. (Source: DrugBank)
* **Liver Toxicity:** Oral testosterone formulations, although testosterone undecanoate is absorbed through the lymphatic system to bypass some first-pass liver metabolism, still carry a theoretical risk of liver toxicity. Liver function tests may be monitored. (Source: EMA SmPC)
* **Sleep Apnea:** Testosterone therapy may worsen or induce sleep apnea, especially in men with risk factors such like obesity or chronic lung disease. Patients should be monitored for new or worsening sleep apnea symptoms.
* **Fluid Retention:** Testosterone can cause sodium and water retention, potentially worsening conditions like congestive heart failure, renal impairment, or pre-existing edema. (Source: NIH ODS)
* **Fertility:** Exogenous testosterone suppresses endogenous testosterone production and spermatogenesis, potentially impairing fertility. This effect can be reversible but may be prolonged or permanent.
* **Abuse Potential:** Testosterone is a controlled substance and has a potential for abuse, particularly by athletes and bodybuilders for non-medical purposes, which can lead to serious adverse events.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Testosterone undecanoate is contraindicated in several situations due to the potential for significant adverse outcomes. These contraindications are critical to consider before initiating therapy:
* **Known or Suspected Prostate Cancer:** Testosterone can stimulate the growth of prostate cancer cells; therefore, it is absolutely contraindicated in men with this diagnosis. (Source: FDA label)
* **Male Breast Cancer:** Similarly, testosterone is contraindicated in men with known or suspected breast cancer. (Source: MedlinePlus)
* **Severe Cardiac, Renal, or Hepatic Disease:** Due to the potential for fluid retention and other metabolic effects, testosterone therapy can exacerbate these conditions. (Source: DrugBank)
* **Pregnancy and Breastfeeding:** Testosterone is categorized as a Class X drug in pregnancy due to the risk of virilization of a female fetus. It is not indicated for use in women, especially during pregnancy or breastfeeding. (Source: FDA label)
* **Hypersensitivity:** Individuals with a known hypersensitivity or allergic reaction to testosterone undecanoate or any of its excipients should not use this medication.
* **Polycythemia Vera or Untreated Erythrocytosis:** Due to the risk of exacerbating elevated red blood cell count and increasing thrombotic risk.
The decision to prescribe testosterone undecanoate must involve a careful evaluation of these contraindications and a thorough discussion of risks versus benefits with a qualified clinician. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Due to potential for drug interactions, it is important to be aware of substances that should not be combined with testosterone undecanoate or require careful monitoring:
* **Anticoagulants (e.g., Warfarin):** Testosterone can increase the anticoagulant effect of warfarin and other oral anticoagulants, leading to an increased risk of bleeding. Close monitoring of INR and prothrombin time is necessary. (Source: MedlinePlus)
* **Corticosteroids:** Concomitant administration with corticosteroids may increase the risk of edema (fluid retention). This combination should be used with caution, especially in patients with cardiac, hepatic, or renal disease. (Source: DrugBank)
* **Insulin and Oral Hypoglycemic Agents:** Testosterone may decrease blood glucose levels. For diabetic patients, the dose of insulin or oral hypoglycemic agents may need to be adjusted to avoid hypoglycemia. (Source: NIH ODS)
* **Drugs Metabolized by CYP450 Enzymes:** While not extensively studied for testosterone undecanoate specifically, testosterone itself can potentially interact with drugs metabolized by certain cytochrome P450 enzymes. Caution is advised with drugs that are sensitive substrates or inhibitors/inducers of these enzymes.
* **Diuretics:** Co-administration may alter electrolyte balance or fluid retention. (Source: Mayo Clinic)
* **Thyroid Hormones:** Testosterone may decrease levels of thyroid-binding globulin, potentially requiring dose adjustments of thyroid hormone replacement therapy.
Always inform your healthcare provider about all medications, supplements, and herbal products you are currently taking to avoid potentially harmful interactions. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
The typical timing for testosterone undecanoate administration varies significantly depending on the formulation and individual needs.
For **intramuscular injections** (e.g., Nebido, Aveed), due to its long half-life of approximately 720 hours (30 days), injections are typically administered every 10 to 14 weeks after an initial loading phase. The initial loading phase often involves two injections separated by an interval of 4 to 6 weeks to quickly achieve steady-state testosterone levels. Subsequent injections are then given at longer, regular intervals as determined by the prescribing clinician, based on individual response and serum testosterone levels. Dosing should always be user-directed and must be set by a licensed clinician. It can be taken either with or without food for intramuscular administration.
For **oral capsules** (e.g., Andriol), the timing is different. The oral formulation is typically taken with food, as food (particularly fatty meals) assists in its absorption through the lymphatic system, bypassing significant first-pass metabolism in the liver. Doses are usually divided and taken two or three times daily. Adherence to taking it with meals is crucial for consistent absorption and efficacy. Dosing should always be user-directed and must be set by a licensed clinician. (Source: DrugBank, FDA label, EMA SmPC)
Source for this section: Sources for When should you take Testosterone Undecanoate?: Jumps to this entry in the sources and references list at the end of the page.
What interacts with Testosterone Undecanoate?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Any peptide + hormone | Note | Category ruleConfidence: theoretical | Injectable peptides plus hormones can have overlapping or compounding effects that aren't always well characterized.Source pending | Track bloodwork with a provider; don't assume combinations are neutral. |
Frequently asked questions about Testosterone Undecanoate
For injectable forms, patients often experience an initial improvement in symptoms within a few weeks, but full therapeutic effects on muscle mass, bone density, and mood may take several months to develop after achieving stable testosterone levels. Oral forms may act quicker for some symptoms but require consistent dosing.
Testosterone undecanoate treats the symptoms of hypogonadism by supplementing testosterone. It typically does not 'cure' the underlying condition causing low testosterone, meaning treatment is usually long-term to maintain benefits. If an underlying cause is treatable, that would be a separate medical approach.
Testosterone undecanoate is not typically indicated for use in women, particularly not for fertility management. Androgen therapy in women is largely outside standard practice for testosterone replacement and carries risks of virilization (e.g., deepening voice, hair growth, clitoral enlargement).
Yes, regular monitoring by a healthcare provider is crucial. This includes periodic blood tests to check testosterone levels, hematocrit (to monitor for erythrocytosis), PSA (prostate-specific antigen) and prostate examinations, and liver function tests, especially with oral formulations. This helps ensure efficacy and manage potential side effects.
The primary difference lies in their administration, pharmacokinetic profiles, and common uses. Injectable testosterone undecanoate provides a very long-acting and stable release of testosterone, allowing for infrequent dosing (e.g., every 10-14 weeks). Oral testosterone undecanoate is typically taken daily with food to aid absorption and has a different metabolic pathway, circumventing some first-pass liver metabolism but exhibiting more variable absorption.
Interaction risk for Testosterone Undecanoate comes from the rest of the stack: other hormones, prescription medicines, hormone therapy and peptides. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers Testosterone Undecanoate with no sign-up.
Testosterone Undecanoate is administered by injection, so the measured volume — not a tablet count — is the unit that matters. It is a controlled substance in some jurisdictions, so the prescribed amount is the only appropriate one. Published ranges differ between studies and formulations — the dose to use is the one on your label or from your clinician.
There is no single answer for Testosterone Undecanoate plus TRT. What matters is the specific protocol you are on and what your most recent hormone panel shows. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
Pairing Testosterone Undecanoate with peptides has to be assessed one peptide at a time, because GLP-1 agonists, secretagogues, healing peptides and melanocortins do not share an interaction profile. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
Published frequency for Testosterone Undecanoate varies by protocol and formulation, so the label or prescription is what sets it. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
The effect of a missed dose of Testosterone Undecanoate depends on the protocol and formulation you are on. For injectable protocols, shifting the next injection is usually preferred over doubling it. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For an injectable like Testosterone Undecanoate the record needs more than a checkbox: vial concentration, the measured volume, and which site the last injection went into. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
Which studies looked at Testosterone Undecanoate?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.Testosterone replacement therapy and spermatogenesis in reproductive age men(opens PubMed in a new tab)Nat Rev Urol · 2025 · PMID 40346275 · https://pubmed.ncbi.nlm.nih.gov/40346275/
- 2.Testosterone treatment to prevent or revert type 2 diabetes in men enrolled in a lifestyle programme (T4DM): a randomised, double-blind, placebo-controlled, 2-year, phase 3b trial(opens PubMed in a new tab)Lancet Diabetes Endocrinol · 2021 · PMID 33338415 · https://pubmed.ncbi.nlm.nih.gov/33338415/
- 3.Testosterone Undecanoate-Schering AG(opens PubMed in a new tab)Drugs R D · 2004 · PMID 15563244 · https://pubmed.ncbi.nlm.nih.gov/15563244/
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- PubChem CID 65157(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/65157
Verify at
Publisher search links for Testosterone Undecanoate. These are places to check the information — they are not citations, so they are not numbered.
- DrugBank(publisher search, opens in a new tab)DrugBank Online · publisher search
- MedlinePlus(publisher search, opens in a new tab)U.S. National Library of Medicine · publisher search
- Mayo Clinic(publisher search, opens in a new tab)Mayo Clinic · publisher search
- NIH Office of Dietary Supplements(publisher search, opens in a new tab)National Institutes of Health · publisher search
- FDA-approved labeling (DailyMed)(publisher search, opens in a new tab)U.S. Food and Drug Administration · publisher search
- European Medicines Agency(publisher search, opens in a new tab)European Medicines Agency · publisher search
- Cochrane Library(publisher search, opens in a new tab)Cochrane · publisher search
- Examine.com(publisher search, opens in a new tab)Examine.com · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on Testosterone Undecanoate?
Plain-text summary, safe to quote verbatim:
Testosterone undecanoate is an esterified form of the androgen testosterone, primarily used in testosterone replacement therapy (TRT) for men with clinical hypogonadism. Research on Testosterone Undecanoate focuses on testosterone support, cognition and mood, and libido. Testosterone Undecanoate is administered by injection rather than orally.
Source: DoseRoutine — https://doseroutine.com/library/testosterone-undecanoate
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). Testosterone Undecanoate — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/testosterone-undecanoate
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