Men's health
Testosterone replacement
Testosterone therapy for hypogonadism — Replaces testosterone in men with confirmed deficiency — not a general tonic.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Testosterone replacement treats men with hypogonadism — a genuine deficiency of testosterone confirmed by symptoms and blood tests — to improve symptoms such as low libido, fatigue, mood and bone and muscle health.
How it works
It restores testosterone to a normal range in men who cannot produce enough themselves, supporting the many functions the hormone governs. Because it signals the body that levels are sufficient, it also switches off the body's own testosterone and sperm production while in use.
In practice
In practice the most important step comes before prescribing: testosterone is for confirmed hypogonadism — diagnosed with symptoms plus repeated, properly timed (early-morning) low testosterone levels and appropriate work-up — not for normal age-related changes or as a lifestyle or performance aid, where it has no proven benefit and real risks. Once started, the practical monitoring centres on the blood count and the prostate: testosterone can raise the red-cell count (polycythaemia), which thickens the blood and raises clot risk, so haematocrit is checked, and it can stimulate prostate tissue, so prostate symptoms and PSA are monitored. Patients are counselled that it suppresses the body's own production and sperm count, so it is not used when fertility is desired. Levels and symptoms guide dose, and the route (gel, injection) is chosen to suit the patient, with gels needing care to avoid skin transfer to women and children.
Examples
Practical use
How to take it & use it well
- Testosterone replacement is used only when low testosterone is confirmed by symptoms and blood tests, and is available as gels, patches or injections.
- Follow the prescribed method carefully; gels are applied to clean, dry skin and injections are given at set intervals by a health professional or, in some cases, yourself.
- Have regular blood tests to check testosterone levels, your blood count and prostate marker (PSA), as advised by your team.
- If using a gel, let it dry, wash your hands, and cover the area, because skin-to-skin contact can transfer testosterone to women and children.
- Tell your team if you are trying to father a child, as treatment can reduce fertility.
- Do not use testosterone simply to boost energy or muscle without a confirmed deficiency, as this carries risks.
Common uses
- Confirmed male hypogonadism (symptoms plus low morning testosterone)
- Replacement after specific testicular or pituitary problems
Monitoring
- Testosterone level and symptom response
- Haematocrit/full blood count and PSA/prostate assessment
- Mood and cardiovascular risk factors
Weighing it up
Advantages & disadvantages
Advantages
- Can relieve symptoms of genuine testosterone deficiency such as low energy, low mood, reduced libido and muscle loss.
- Improves wellbeing and sexual function for many men with confirmed low levels.
- Different formulations allow treatment to suit your preferences and lifestyle.
- Can help maintain bone strength and muscle mass when deficiency is the cause.
Disadvantages
- Can thicken the blood (polycythaemia), raising the risk of clots, so the blood count is monitored.
- May stimulate the prostate, so PSA and prostate health are checked before and during treatment.
- Can reduce sperm production and fertility.
- Gels can transfer to others through skin contact, which is harmful to women and children.
- Not appropriate without a confirmed diagnosis, and may cause acne, fluid retention or mood changes.
Key safety principles
What to watch for
- Only for confirmed deficiency — not for normal ageing, lifestyle or performance.
- Can raise the red-cell count (polycythaemia → clot risk) — monitor haematocrit; can stimulate prostate tissue — monitor PSA/prostate.
- Suppresses natural production and fertility — avoid when fatherhood is desired; gels can transfer to others by skin contact.
Key interactions
What to avoid or check alongside
- Can increase the effect of warfarin and other anticoagulants, raising bleeding risk and needing closer monitoring.
- May affect blood sugar control, so diabetes medicines and monitoring may need review.
- Combining with medicines or conditions that already raise the blood count adds to the clotting risk.
- Tell your team about all medicines, as testosterone can interact with some hormone-related treatments.
Patient & carer advice
- This is treatment for a proven deficiency, not a general energy or performance booster
- Attend blood tests — we watch your blood thickness and prostate
- With gels, wash hands and cover the area to avoid transferring it to women or children
Use with
Related clinical calculators
Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
Testosterone replacement: frequently asked questions
Do I need a blood test before starting testosterone?
Yes. Testosterone replacement should only be started when low testosterone is confirmed by symptoms together with blood tests, usually taken in the morning and repeated. It is not recommended just to boost energy or performance.
Why is my blood count checked on testosterone?
Testosterone can thicken the blood, a condition called polycythaemia, which raises the risk of clots. Your blood count is checked regularly so treatment can be adjusted if it rises too high.
Can testosterone gel affect my partner or children?
Yes. The gel can transfer through skin contact and is harmful to women and children. Let it dry fully, wash your hands, cover the area and avoid skin-to-skin contact with the treated site.
Will testosterone affect my fertility?
Testosterone replacement can reduce sperm production and lower fertility. If you are hoping to father a child, tell your team, as other approaches may be more suitable.
Why is my prostate checked during treatment?
Testosterone can stimulate prostate tissue, so a prostate marker called PSA and your prostate health are checked before and during treatment to monitor for any changes.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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