テストステロン注射：自分でそれを行う方法

最終更新日： 8月 29, 2026

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Men on testosterone replacement therapy often ask whether they can give the injection themselves rather than coming to the hospital every few weeks. For some men the answer is yes. But the technique is the smallest part of the answer, and this article deliberately spends more time on the parts that actually decide whether testosterone therapy is safe.

Read this part first

Not every testosterone injection can be given at home. Long-acting testosterone undecanoate is a different product from the shorter-acting esters, and it must be given in a medical setting with a period of observation afterwards, because of a rare reaction in which the oil enters the lungs. It is never a home self-injection. Nothing below applies to it.

The dose, the preparation and the interval are set by the doctor who prescribes them, on the basis of your blood results, and are adjusted over time. They are not something to choose, increase or shorten yourself, and this article deliberately does not give a dose. Higher is not better: the aim is a level in the normal range with your symptoms improved, not the highest number you can reach.

Never buy testosterone from an unregulated source. With products bought online or from a gym, neither the dose nor the contents can be relied upon, and nobody is checking your blood.

Get help the same day if any of these happen

Go to an emergency department, or call 1669 in Thailand, if you develop:

• Chest pain, or breathlessness that comes on with less exertion than usual
• Pain, swelling or warmth in one calf, or sudden breathlessness with chest pain on breathing in — these can mean a clot in the leg or the lung
• Sudden severe headache, weakness or numbness down one side, or difficulty speaking, even if it passes
• At the injection site: spreading redness, increasing pain after the first couple of days, fever, or discharge — that is infection, not ordinary soreness

These are symptoms anyone should act on regardless of what medication they take; listing them here is prudence rather than a claim that testosterone caused them. Do not stop a prescribed medicine on your own because of something you have read here. Tell the doctor who prescribed it instead.

What Testosterone Therapy Asks of You

These apply to every route — gel or injection — and they matter far more than injection technique.

It suppresses your own sperm production. Testosterone given from outside switches off the signal from the brain that drives the testicles, and sperm counts commonly fall to zero. This is the single most important thing to raise before the first dose. It is usually reversible after stopping, but recovery takes months and cannot be guaranteed in every man. If you may want children now or later, say so before you start — fertility-sparing options such as clomiphene citrate, hCG or an aromatase inhibitor raise your own testosterone instead, and a semen analysis beforehand is worth having.

It thickens the blood. Testosterone stimulates red cell production, and a rising haematocrit is the finding that most often forces a dose reduction, a change of route, or a pause. This was also the clearest adverse effect in the TRAVERSE trial, the largest safety study in the field — which is worth knowing, because it is the one part of the monitoring that is genuinely evidence-driven rather than precautionary. It is checked before starting and at intervals afterwards. You cannot feel it — which is exactly why the blood tests are not optional.

Your prostate is followed, not ignored. PSA and a prostate assessment are checked before starting and monitored during treatment.

Sleep apnoea can worsen. If you snore heavily, stop breathing in your sleep, or wake unrefreshed, that should be looked into — treating it sometimes improves the very symptoms that sent you looking for testosterone in the first place.

Other effects worth knowing about: acne and oily skin, breast tenderness or enlargement, mood changes, testicular shrinkage and fluid retention. None are reasons to panic; all are reasons to be reviewed rather than to adjust your own dose.

Why the Thigh, and Why Never the First Time Alone

Intramuscular testosterone is normally given into the buttock by a nurse or doctor. For self-injection that site is impractical — you cannot see it properly — so the outer thigh is used instead: the middle third of the outer thigh, taking the distance from hip to knee and using the section between the two.

Do not attempt your first injection on your own. The first doses are given, or directly supervised, by a healthcare professional, and you continue under supervision until both you and they are satisfied you are competent. Everything below is a reminder of what you were taught in person — it is not a substitute for being taught.

What you will have been given

Alcohol swabs; the testosterone preparation your doctor prescribed, in date; a syringe; a wider needle for drawing the oil out of the vial; and a second, finer needle for the injection itself. For the shorter-acting enanthate preparation taught here, that is typically a 18G needle to draw up and a 24G needle to inject — the drawing-up needle is deliberately wide because the solution is oily and slow to pull through, while the injecting needle is fine because the volume is small. Confirm both with whoever taught you, since they differ between preparations and with your build, and a thicker or larger-volume product needs a wider injecting needle than this. Use a new needle every time, never reuse or share one, and dispose of used needles in a proper sharps container rather than in household rubbish.

The sequence

1. Wash your hands. Sit comfortably with everything laid out within reach.
2. Choose which thigh, and alternate sides each time so one area is not used repeatedly.
3. Identify the middle third of the outer thigh.
4. Clean the skin with alcohol and let it dry completely before the needle goes in.
5. Check the vial: the right medicine, in date, and the solution clear rather than cloudy or containing particles.
6. Draw up the prescribed amount using the drawing-up needle.
7. Expel the air from the syringe.
8. Change to the injecting needle.
9. Insert the needle smoothly, at ninety degrees to the skin and at the depth you were shown.
10. Pull back gently on the plunger before injecting. If no blood appears, go ahead. If blood does appear, stop — withdraw, dispose of that needle and syringe, and start again with a fresh set at a slightly different spot. Do not simply reposition and push on with the same syringe. This step is taught here because testosterone is an oil, and oil is one thing you do not want going into a vein.
11. Inject slowly — oily solutions hurt more when pushed quickly.
12. Withdraw and press gently on the site with clean gauze. Do not massage it.
13. Dispose of the needle and syringe in the sharps container.

Aching at the site for a day or two is normal and settles. Increasing pain after that, spreading redness, fever or discharge is not — see the red-flag list above. If a dose is missed, or an injection does not go as planned, contact the clinic rather than repeating it or doubling up.

Is Injection Even the Right Route for You?

Testosterone replacement at Bangkok Hospital Headquarters is given as a transdermal gel or as an injection. Gels give smoother, steadier levels and are quickly reversible if a side effect appears, at the cost of a daily routine and the need to avoid transferring the gel to a partner or, more importantly, a child. Injections avoid transference entirely and cost less, at the cost of the needle and of more variation in levels between doses. There is also a subcutaneous route, which uses a much finer needle just under the skin, hurts less and gives steadier levels than the intramuscular route described here — it is worth asking about, particularly if your haematocrit has been creeping up.

Related reading: why testosterone is a barometer of overall health, fertility, prostate cancer and heart health on testosterone, what the TRAVERSE trial actually found, the four causes of erectile dysfunction, and the full テストステロン補充療法 service page.

お客様からよくいただくご質問

Can I inject testosterone myself at home?

Some men can, for the shorter-acting intramuscular and subcutaneous preparations, but only after being taught and supervised in person until both you and your clinician are satisfied you are competent. The first injection is never done alone. Long-acting testosterone undecanoate is the exception that is never self-injected at all — it is given in a medical setting with observation afterwards.

Where is the injection given?

Intramuscular testosterone is usually given into the buttock in clinic. For self-injection the middle third of the outer thigh is used instead, because you can see and reach it. Sides are alternated so the same area is not used repeatedly. Subcutaneous injection uses a different, much finer technique and a different site.

What dose and how often?

That is set by the doctor who prescribes it, from your blood results, and adjusted over time — it differs between preparations and between men, so no figure is given here. Do not increase the dose or shorten the interval yourself if you feel flat before the next one is due; tell your doctor, because the answer is often a change of route or a different interval rather than more testosterone.

Does testosterone therapy affect fertility?

Yes, and it is the most important question to settle before starting. Testosterone given from outside suppresses the brain signal that drives the testicles, and sperm production commonly falls to zero, whichever route is used. It is usually reversible after stopping, but recovery takes months and cannot be guaranteed. If you may want children now or in the future, say so before the first dose — clomiphene citrate, hCG or an aromatase inhibitor raise your own testosterone instead, and a semen analysis beforehand is worth having.

What monitoring is needed while on testosterone?

Haematocrit, testosterone level, PSA and a prostate assessment before starting and at intervals during treatment. A rising haematocrit is the finding that most often forces a change of dose or route, and it produces no symptoms you could notice yourself — it was also the clearest adverse effect in the TRAVERSE trial, so this is the part of the monitoring with the strongest evidence behind it. Blood pressure is also followed. Monitoring is part of the treatment, not an optional extra.

What problems after an injection need urgent attention?

Go to an emergency department the same day, or call 1669 in Thailand, for chest pain; breathlessness on less exertion than usual; pain, swelling or warmth in one calf; sudden breathlessness with chest pain on breathing in; or a sudden severe headache, one-sided weakness or numbness, or difficulty speaking, even if it resolves. At the injection site, spreading redness, pain that increases after the first couple of days, fever or discharge means infection and needs same-day assessment.

Book an Appointment

Dr. Soarawee Weerasopone sees men’s health and testosterone patients at バンコク病院本部 and at Samitivej Sriracha Hospital, Chonburi — Urology department 088-022-1445. Diagnosis comes first: testosterone deficiency means a low level confirmed on two early-morning blood tests together with real symptoms. Questions about cost are answered by the hospital, not by Dr. Soarawee — for Bangkok Hospital, by email to bhquro@bdms.co.th.

バンコク病院の遠隔医療は、来院が困難な患者様（海外からの患者様を含みます）を対象にご利用いただけます。泌尿器科宛てに事前にメールでご手配ください。 bhquro@bdms.co.th. Samitivej Sriracha is in-person only.

免責事項 This article is written and reviewed by Dr. Soarawee Weerasopone, a board-certified urologist at Bangkok Hospital Headquarters. It is educational only, is not medical advice, and does not create a doctor–patient relationship. It is written as a reminder for men who have already been prescribed testosterone and taught to inject in person — it is not instruction to begin injecting, and it cannot substitute for that teaching. Do not start, stop or change a prescribed dose on your own. No diagnosis, prescription or individual medical advice is given through personal messaging channels or social media, and Dr. Soarawee operates no public social media account — any account offering private consultation in his name is fraudulent. Always consult a qualified healthcare professional before starting any medical treatment.