Androgen — Male Hypogonadism Pregnancy: Not indicated for use in women; must not be used in pregnant or breast-feeding women. Testosterone replacement may reversibly reduce spermatogenesis.

Testosterone

Brand names: Testogel (gel), Nebido (IM depot), Testim (gel), Sustanon (IM)

Testosterone replacement therapy, available as gels, transdermal and injectable preparations, is used to treat confirmed male hypogonadism (testosterone deficiency).

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: 1000 mg (one ampoule/vial of testosterone undecanoate 1000 mg/4 ml)

Route: Intramuscular (deep gluteal injection, given very slowly over 2 minutes; avoid intravasal injection)

Frequency: Every 10 to 14 weeks

For testosterone replacement in male hypogonadism (product: testosterone undecanoate 1000 mg/4 ml solution for injection). Measure serum testosterone before and during initiation. Loading: the first injection interval may be shortened to a minimum of 6 weeks to reach steady state more rapidly. Maintenance: keep interval within 10 to 14 weeks; measure testosterone at the end of an interval, aiming for the lower third of the normal range; below-range levels indicate a shorter interval, high levels a longer one. Not indicated in children/adolescents and not evaluated in males under 18. Limited data suggest no dose adjustment needed in the elderly. Contraindicated in men with past or present liver tumours; no formal studies in hepatic impairment.

Dose adjustments

Renal

No formal studies performed in patients with renal impairment.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. 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
Past or present liver tumours
Hypersensitivity to the active substance or to any excipient
Contraindicated for use in women

Side effects

Acne (common)
Injection site pain (common)
Polycythaemia; haematocrit, haemoglobin and red blood cell count increased (common)
Weight increased and hot flush (common)
Pulmonary oil microembolism (rare) - cough, dyspnoea, chest pain, dizziness, syncope during or immediately after injection

Clinical monograph

How it works

It replaces endogenous androgen, binding androgen receptors to restore secondary sexual characteristics, libido, muscle and bone mass, and to suppress the symptoms of deficiency.

Prescribing in practice

It is contraindicated in known or suspected prostate or breast cancer and must only be started after biochemically confirmed deficiency on morning samples.
Therapy can raise haematocrit (causing polycythaemia and thrombotic risk) and may worsen lower urinary tract symptoms or unmask prostate disease.
Topical gels can transfer to partners and children on skin contact, so application sites should be covered and washed.

Monitoring

Monitor testosterone levels, haematocrit, prostate-specific antigen and prostate symptoms before and periodically during treatment.

Counselling the patient

With gels, cover the application area and avoid skin-to-skin contact with women and children until absorbed.
Attend blood tests as scheduled to check red cell count and prostate marker.

Evidence & guidelines

Endocrine and urology guidelines recommend testosterone replacement only for symptomatic, biochemically confirmed hypogonadism, with structured safety monitoring.

Reference: NICE NG227 (Testosterone for male hypogonadism); EAU Male Hypogonadism Guidelines 2024; Endocrine Society Guidelines 2018; 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.

Pathways