Long-acting testosterone ester Pregnancy: Testosterone Enantate is intended for use by men only. It is not indicated in pregnant women and is not indicated in breast feeding women. Fertility: testosterone enantate replacement therapy may reversibly reduce spermatogenesis.

Testosterone enantate

Testosterone enantate is a long-acting testosterone ester given by intramuscular injection for androgen replacement in men with hypogonadism. The single ester provides a depot effect over a period of weeks.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: To stimulate development of underdeveloped androgen-dependent organs and for initial treatment of deficiency symptoms: 250 mg testosterone enantate intramuscularly every two to three weeks. For maintenance treatment: 250 mg testosterone enantate intramuscularly every three to six weeks, according to individual requirement.

Route: Intramuscular injection (oily solution) — the injection must be administered extremely slowly, and the oily solution is injected immediately after being drawn up into the syringe

Frequency: Initial treatment: every 2 to 3 weeks. Maintenance: every 3 to 6 weeks, according to individual requirement.

Serum testosterone levels should be measured before the start of treatment and occasionally during treatment at the end of an injection interval. Serum levels below the normal range would indicate the need for a shorter injection interval; in the case of high serum levels an extension of the injection interval may be considered. Clinicians should adjust the dosage individually to ensure maintenance of eugonadal testosterone levels. Carcinoma of the prostate must be excluded before starting therapy, and regular prostate examinations are recommended in men as a precaution. In patients on long-term androgen therapy, monitor haemoglobin and haematocrit (to detect polycythaemia), liver function tests and lipid profile regularly. Use with caution in men with hypertension, and in patients with epilepsy, migraine, diabetes mellitus or skeletal metastases; caution in patients predisposed to oedema; caution in patients with thrombophilia or risk factors for venous thromboembolism. In patients with severe cardiac, hepatic or renal insufficiency or ischaemic heart disease, treatment may cause severe complications characterised by oedema with or without congestive cardiac failure — in such cases treatment must be stopped immediately. Elderly: limited data do not suggest the need for a dosage adjustment; there is limited experience of safety and efficacy in patients over 65 years. Hepatic impairment: no formal studies performed; contraindicated in men with past or present liver tumours. Paediatric population: 'Testosterone Enantate is not indicated for use in children and adolescents. Safety and efficacy have not been adequately determined in children and adolescents.' NOTE: the fetched SPC section 4.4 was truncated at the source-fetch limit and section 4.5 (interactions) was not retrieved — no interaction list is given below.

Dose adjustments

Renal

No formal studies have been performed in patients with renal impairment. (Treatment may cause severe complications characterised by oedema with or without congestive cardiac failure in patients with severe renal insufficiency — treatment must then be stopped immediately.)

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Androgen-dependent carcinoma of the prostate or of the male mammary gland
Hypercalcaemia
Past or present liver tumours
Nephrosis

Side effects

Weight increased, haematocrit increased, red blood cell count increased, haemoglobin increased (common)
Pulmonary oil microembolism (rare)
Injection site reactions — pain, erythema, induration, swelling, inflammation, haematoma (frequency not known)
Polycythaemia (frequency not known)
Acne, alopecia, rash, urticaria, pruritus, male pattern baldness (frequency not known)
Benign and malignant liver tumours, jaundice, liver enlargement, intra-abdominal haemorrhage (frequency not known)
Gynaecomastia, prostatic disorder, benign prostatic hyperplasia, abnormal spermatogenesis, prostate specific antigen increased (frequency not known)

Clinical monograph

How it works

It is slowly hydrolysed after injection to release testosterone, which acts on androgen receptors to maintain male secondary sexual characteristics, libido, muscle mass, bone density, and spermatogenesis.

Prescribing in practice

It is contraindicated in known or suspected prostate or breast carcinoma in men, so prostate assessment and PSA (where appropriate) should be undertaken before and during treatment, as androgens can promote existing prostate cancer.
Polycythaemia is a recognised effect, so haematocrit should be monitored periodically.
It is contraindicated in pregnancy owing to the risk of virilising a female foetus, and is administered by deep intramuscular injection.

Monitoring

Monitor serum testosterone to optimise the dosing interval, alongside haematocrit, prostate status, PSA, lipids, and liver function during long-term use.

Counselling the patient

This medicine is given as a deep injection into a muscle.
Report trouble passing urine, breast swelling or tenderness, or unusual mood changes.
Tell your clinician if you are planning to father a child, as treatment can affect fertility.

Evidence & guidelines

Its role in male hypogonadism is well established through extensive clinical use and endocrine guideline recommendations for testosterone replacement.

Reference: UK Endocrine Society; 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).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Testosterone undecanoate · Long-acting testosterone ester

Pathways