testosterone undecanoate at a glance
Medicine class
Androgen hormone replacement
Usual role
Replacement therapy for confirmed male hypogonadism
Administration
A healthcare professional injects this oil-based depot deeply into a buttock muscle and observes the patient during and immediately afterwards.
What is testosterone undecanoate used for?
Its licensed use is:
Testosterone replacement in men with hypogonadism when deficiency has been confirmed by clinical features and biochemical tests.
How does testosterone undecanoate work?
It forms a depot in the muscle and is gradually released and converted to testosterone. Testosterone activates androgen receptors; some is also converted to dihydrotestosterone or oestradiol in target tissues.
testosterone undecanoate preparations and strengths
Injection
Route: Parenteral
Strengths: 1000 mg/4 mL
How to take testosterone undecanoate
This formulation is not swallowed. A trained healthcare professional injects it very slowly and deeply into a buttock muscle, avoiding blood vessels. The single-use oily solution should be clear and free from particles.
Remain available for observation during and immediately after the injection.
Immediately report coughing, breathlessness, chest discomfort, dizziness, tingling or faintness.
Do not self-inject unless a suitably qualified clinician has arranged and taught you to do so.
testosterone undecanoate side effects
Common or expected effects
- Acne
- Injection-site pain, bruising or irritation
- Increased red-cell count or haematocrit
- Weight gain
- Hot flushes
- Raised prostate-specific antigen or prostate enlargement
Get urgent medical advice
- Sudden cough, breathlessness, chest pain, sweating, dizziness, tingling or fainting during or immediately after injection
- Severe allergic reaction, including facial or throat swelling or breathing difficulty
- Possible blood clot: painful one-sided leg swelling, sudden chest pain, coughing blood or sudden visual loss
- Persistent painful erection
- Marked fluid retention, particularly with breathlessness or worsening heart failure
testosterone undecanoate in pregnancy
This product is not indicated for women and must not be used during pregnancy. Anyone who could become pregnant should discuss treatment and contraception with their specialist prescriber. Testosterone can suppress ovulation and fertility but is not contraception.
testosterone undecanoate while breastfeeding
This product must not be used while breastfeeding. Specialist advice is required if treatment is being considered or continued after pregnancy.
testosterone undecanoate interactions
Tell the prescriber about all medicines, particularly:
Coumarin oral anticoagulants, such as warfarin
Testosterone may increase anticoagulant activity and bleeding risk, so closer INR monitoring may be required when treatment starts or stops.
Insulin and other glucose-lowering medicines
Improved insulin sensitivity may lower glucose and alter the amount of diabetes treatment required.
SGLT2 inhibitors
Combined use may further increase red-cell count, so haemoglobin and haematocrit require monitoring.
Common questions about testosterone undecanoate
Answers are fully visible for fast scanning and source review.
Why are blood tests needed before it is prescribed?
Symptoms alone are insufficient. Deficiency should be confirmed by two separate testosterone measurements, and other causes should be considered.
Can the injections be self-administered?
This product requires careful deep intramuscular administration and post-injection observation, so it is normally given by a trained healthcare professional.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.