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Long-acting testosterone ester Pregnancy: §4.6, verbatim: 'Fertility: Testosterone replacement therapy may reversibly reduce spermatogenesis (see sections 4.8 and 5.3). Pregnancy and breastfeeding: Nebido is not indicated for use in women and must not be used in pregnant or breast-feeding women (see section 4.3).' §4.3 states outright that 'The use of Nebido in women is contraindicated.' Cross-check (US TLANDO label §8.1, different product): 'Testosterone is teratogenic and may cause fetal harm when administered to a pregnant woman based on data from animal studies and its mechanism of action. Exposure of a female fetus to androgens may result in varying degrees of virilization.'

Testosterone undecanoate

Brand names: Nebido, Restandol Testocaps

Testosterone undecanoate is a long-acting testosterone ester available as a depot intramuscular injection and as an oral preparation, used for testosterone replacement in men with hypogonadism. The injectable form gives a prolonged effect with infrequent dosing.

Adult dose

Dose: 1000 mg (the contents of one 1000 mg / 4 mL ampoule or vial) by deep intramuscular injection every 10 to 14 weeks, for male hypogonadism. SCOPE: this is the INTRAMUSCULAR DEPOT (Nebido) regimen only — the oral Restandol Testocaps regimen also listed on this page is not dosed anywhere in this bundle (see notes).
Route: Deep intramuscular injection into the gluteal muscle, given very slowly over two minutes. §4.2 Method of administration, verbatim: 'For intramuscular use. The injections must be administered very slowly (over two minutes). Nebido is strictly for intramuscular injection. Care should be taken to inject Nebido deeply into the gluteal muscle following the usual precautions for intramuscular administration. Special care must be taken to avoid intravasal injection.' The contents of an ampoule/vial are to be injected immediately after opening.
Frequency: Every 10 to 14 weeks for maintenance. At the start of treatment the first injection interval may be shortened as a loading dose — §4.2, verbatim: 'Depending on serum testosterone levels and clinical symptoms, the first injection interval may be reduced to a minimum of 6 weeks as compared to the recommended range of 10 to 14 weeks for maintenance.'
Max: Not stated — §4.2 sets no maximum dose and no maximum cumulative dose for Nebido. What it constrains is the injection interval, not the amount given (see the frequency field); the amount injected is always one full 1000 mg ampoule/vial.
VERBATIM §4.2 Posology: 'One ampoule / vial of Nebido (corresponding to 1000 mg testosterone undecanoate) is injected every 10 to 14 weeks. Injections with this frequency are capable of maintaining sufficient testosterone levels and do not lead to accumulation.' START OF TREATMENT, verbatim: 'Serum testosterone levels should be measured before start and during initiation of treatment. Depending on serum testosterone levels and clinical symptoms, the first injection interval may be reduced to a minimum of 6 weeks as compared to the recommended range of 10 to 14 weeks for maintenance. With this loading dose, sufficient steady state testosterone levels may be achieved more rapidly.' MAINTENANCE AND INDIVIDUALISATION, verbatim: 'The injection interval should be within the recommended range of 10 to 14 weeks. Careful monitoring of serum testosterone levels is required during maintenance of treatment. It is advisable to measure testosterone serum levels regularly. Measurements should be performed at the end of an injection interval and clinical symptoms considered. These serum levels should be within the lower third of the normal range. Serum levels below normal range would indicate the need for a shorter injection interval. In case of high serum levels an extension of the injection interval may be considered.' ELDERLY, verbatim: 'Limited data do not suggest the need for a dosage adjustment in elderly patients.' INDICATION GATE (§4.4), verbatim: 'Nebido should be used only if hypogonadism (hyper- and hypogonadotrophic) has been demonstrated and if other aetiology, responsible for the symptoms, has been excluded before treatment is started. Testosterone insufficiency should be clearly demonstrated by clinical features (regression of secondary sexual characteristics, change in body composition, asthenia, reduced libido, erectile dysfunction etc.) and confirmed by two separate blood testosterone measurements.' ORAL ROUTE NOT SOURCED: the page also lists Restandol Testocaps (oral testosterone undecanoate). No UK SPC for any oral testosterone undecanoate was fetched, so no oral dose is asserted. The only oral figure anywhere in this bundle is US labelling for a different product — TLANDO, §2.3, verbatim: 'The recommended dosage of TLANDO is 225 mg (taken as two 112.5 mg capsules), orally twice daily, once in the morning and once in the evening. Take with food.' That same US label states, §2.1, verbatim: 'TLANDO is not substitutable with other oral testosterone undecanoate products.' — so it must NOT be carried across to Restandol. Confirm any oral regimen against the relevant UK SPC before use.

Dose adjustments

Renal

§4.2 'Patients with renal impairment', verbatim: 'No formal studies have been performed in patients with renal impairment.' No dose adjustment is given. §4.4 adds a caution (sentence truncated at the source-fetch limit): 'In patients suffering from severe cardiac, hepatic or renal insufficiency or ischaemic heart disease, treatment with testosterone may cause severe complications characterised by …'

Hepatic

§4.2 'Patients with hepatic impairment', verbatim: 'No formal studies have been performed in patients with hepatic impairment. The use of Nebido is contraindicated in men with past or present liver tumours (see section 4.3).' No dose adjustment is given. §4.4 also warns that severe hepatic insufficiency may lead to severe complications, and that 'Cases of benign and malignant liver tumours have been reported in users of hormonal substances such as androgen compounds. If severe upper abdominal complaints, liver enlargement or signs of intra-abdominal haemorrhage occur in men using Nebido, a liver tumour should be included in the differential-diagnostic considerations.'

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Androgen-dependent carcinoma of the prostate or of the male mammary gland (§4.3)
  • Past or present liver tumours (§4.3)
  • Hypersensitivity to the active substance or to any of the excipients listed in section 6.1 (§4.3)
  • Women — §4.3, verbatim: 'The use of Nebido in women is contraindicated.' §4.6 adds: 'Nebido is not indicated for use in women and must not be used in pregnant or breast-feeding women.'
  • Not a formal §4.3 contraindication but a §4.4 exclusion: 'Nebido is not recommended for use in children and adolescents' and it 'has not been clinically evaluated in males under 18 years of age'

Side effects

  • Most frequently reported (§4.8, verbatim): 'The most frequently reported undesirable effects during treatment with Nebido are acne and injection site pain.'
  • Pulmonary oil microembolism — §4.8, verbatim: 'Pulmonary microembolism of oily solutions can in rare cases lead to signs and symptoms such as cough, dyspnoea, malaise, hyperhidrosis, chest pain, dizziness, paraesthesia, or syncope. These reactions may occur during or immediately after the injection and are reversible.' Reported rarely (≥ 1/10,000 and < 1/1,000 injections)
  • Suspected anaphylactic reactions after injection have been reported (§4.8)
  • Blood: polycythaemia (common); haematocrit increased, red blood cell count increased, haemoglobin increased (§4.8 Table 1)
  • Metabolism: weight increased (common); increased appetite, glycosylated haemoglobin increased, hypercholesterolaemia, blood triglycerides increased, blood cholesterol increased (§4.8 Table 1)
  • Psychiatric: depression, emotional disorder, insomnia, restlessness, aggression, irritability (§4.8 Table 1)
  • Nervous system: headache; migraine, tremor (§4.8 Table 1)
  • Vascular: hot flush; hypertension, dizziness, cardiovascular disorder (§4.8 Table 1)
  • Skin: acne (common); alopecia, erythema, rash, pruritus, dry skin (§4.8 Table 1)
  • Hepatobiliary: liver function test abnormal, aspartate aminotransferase increased (§4.8 Table 1)
  • Renal and urinary: urine flow decreased, urinary retention, urinary tract disorder, nocturia, dysuria (§4.8 Table 1)
  • Prostate: §4.8, verbatim: 'Androgens may accelerate the progression of sub-clinical prostatic cancer and benign prostatic hyperplasia.' Prostatic specific antigen changes are listed under reproductive system and breast disorders (table truncated at the source-fetch limit)
  • Musculoskeletal: arthralgia, pain in extremity, muscle disorder, musculoskeletal stiffness, blood creatine phosphokinase increased (§4.8 Table 1)
  • Fertility — §4.6, verbatim: 'Testosterone replacement therapy may reversibly reduce spermatogenesis.'

Monitoring

  • Serum testosterone before starting and during initiation (§4.2), then regularly; measurements taken at the END of an injection interval, with the trough in the lower third of the normal range — a level below the normal range indicates the interval should be shortened, a high level that it may be extended
  • §4.4, verbatim: 'Testosterone level should be monitored at baseline and at regular intervals during treatment. Clinicians should adjust the dosage individually to ensure maintenance of eugonadal testosterone levels.' Because of laboratory variability, all testosterone measurements should be done in the same laboratory
  • Before starting — §4.4, verbatim: 'Prior to testosterone initiation, all patients must undergo a detailed examination in order to exclude a risk of pre-existing prostatic cancer.'
  • Prostate and breast — §4.4, verbatim: 'Careful and regular monitoring of the prostate gland and breast must be performed in accordance with recommended methods (digital rectal examination and estimation of serum PSA) in patients receiving testosterone therapy at least once yearly and twice yearly in elderly patients and at risk patients (those with clinical or familial factors).'
  • Long-term androgen therapy — §4.4, verbatim: 'the following laboratory parameters should also be monitored regularly: haemoglobin and haematocrit, liver function tests and lipid profile'
  • Serum calcium — §4.4: regular monitoring of serum calcium concentrations is recommended in cancer patients at risk of hypercalcaemia (and associated hypercalciuria) due to bone metastases

Clinical monograph

How it works

The ester is hydrolysed to release testosterone, which acts on androgen receptors to maintain male secondary sexual characteristics, libido, muscle and bone, and spermatogenesis; the oral form is absorbed partly via the lymphatic system, reducing first-pass metabolism.

Prescribing in practice

  • The depot injection carries a recognised risk of pulmonary oil microembolism and anaphylactic reactions, so it must be injected very slowly and deeply, with observation of the patient afterwards.
  • It is contraindicated in known or suspected prostate or breast carcinoma in men, so prostate status, PSA where appropriate, and haematocrit should be assessed before and during treatment.
  • Polycythaemia can occur and the haematocrit should be monitored, while pregnancy is a contraindication because of the risk of virilising a female foetus.

Monitoring

Monitor serum testosterone to guide dosing intervals, together with haematocrit, prostate status, PSA, lipids, and liver function during long-term replacement.

Counselling the patient

  • The depot injection is given slowly into a muscle, and you may be observed afterwards for any breathing or fainting reaction.
  • Report difficulty passing urine, breast swelling, or persistent headache.
  • Take the oral form with food as advised, since this affects how it is absorbed.

Evidence & guidelines

Its use is supported by clinical trials and endocrine guidance on long-acting testosterone replacement in confirmed male hypogonadism.

Reference: UK Endocrine Society; MHRA; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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