If you have been diagnosed with low testosterone, the next questions are usually practical ones. Which treatment will I be on? How often will I need it? What will the blood tests check, and how do I get my prescription filled each time without chasing it?

This guide answers those questions. It explains the TRT medication options used in the UK, how each one is given, the side effects listed in the official product information, the monitoring involved, and how testosterone prescriptions are dispensed and delivered safely. Everything clinical here comes from official UK product information or Pharmazon HomeCare's pharmacist-reviewed TRT guides.

TRT Medication UK at a Glance

What it treats	Male hypogonadism, when testosterone deficiency has been confirmed by clinical features and blood tests
Main forms	Injections and daily transdermal gels
Injection examples	Nebido (testosterone undecanoate), Sustanon 250, testosterone enantate
Gel examples	Testogel, Tostran
Monitoring	Testosterone levels, haematocrit, prostate checks (PSA), liver function and lipids
Legal status	Prescription-only, controlled drug (Class C, Schedule 4 Part 2)
Prescription validity	28 days from the date on the prescription
Fertility	Can reduce sperm production

What Is TRT?

Testosterone replacement therapy (TRT) replaces testosterone in men whose bodies do not make enough. According to the official UK product information, testosterone products are licensed for male hypogonadism when testosterone deficiency has been confirmed by clinical features and biochemical tests.

That means symptoms alone are not enough. Diagnosis needs confirmed low testosterone on blood tests, usually a morning sample, alongside symptoms. Common symptoms of low testosterone include persistent fatigue, reduced libido, low mood and irritability, difficulty maintaining muscle mass, poor concentration and loss of morning erections. Read more in our guide to low testosterone symptoms.

The decision to start TRT, and which medicine and dose to use, is made by your prescriber after assessment. Pharmazon HomeCare is a dispensing pharmacy: we do not prescribe testosterone or assess patients.

Types of TRT Medication Available in the UK

TRT medication falls into two main groups: injections and transdermal gels. Your prescriber chooses based on your blood results, lifestyle and how you respond.

TRT medication options in the UK

Medicine	Active ingredient	Form	How often
Nebido	Testosterone undecanoate	Long-acting injection into the buttock muscle	Every 10 to 14 weeks (the interval can be shorter when starting)
Sustanon 250	Four testosterone esters	Deep intramuscular injection	Usually one 1ml injection every 3 weeks
Testosterone enantate	Testosterone enantate	Intramuscular injection	Initially 250mg every 2-3 weeks maintenance 250mg every 3-6 weeks fro hypogonadism
Testogel 16.2 mg/g	Testosterone	Transdermal gel (pump)	Once daily, preferably in the morning
Tostran 2%	Testosterone	Transdermal gel (pump)	Once daily, in the morning

For a side-by-side comparison, read TRT injections vs gels.

TRT injections

• Nebido is an oily solution given into the buttock muscle. The product information says it should be injected very slowly, over about two minutes. After the starting phase, one injection is given every 10 to 14 weeks.
• Sustanon 250 contains four testosterone esters in an oily solution. The product information states one 1ml injection every 3 weeks is usually adequate. It contains arachis (peanut) oil, so it must not be used by people allergic to peanut or soya.
• Injection side effects can include soreness or bruising at the injection site.

TRT gels

• Testogel 16.2 mg/g is applied once daily to clean, dry skin over both shoulders or both arms. The usual dose is two pump actuations (40.5 mg), up to a maximum of 81 mg a day. Wait at least 1 hour before showering.
• Tostran is applied to the abdomen or both inner thighs each morning, rotating sites. The usual starting dose is 60 mg (3 g of gel), up to a maximum of 80 mg. Wait at least 2 hours before bathing. It is flammable until dry.
• Skin-to-skin transfer: testosterone gel can pass to other people through close contact. Wash your hands after applying, cover the area with clothing once dry, and keep pregnant women and children away from application sites.

TRT Side Effects

Side effects vary by product and person. The official product information for Nebido, Sustanon, Testogel and Tostran lists the following among the commonly reported effects:

TRT injections (e.g. Nebido)	TRT gels (e.g. Testogel, Tostran)
Acne	Skin reactions where the gel is applied (redness, acne, dry skin)
Pain or reactions at the injection site	Raised haematocrit and haemoglobin
Raised haematocrit (polycythaemia)	Raised blood pressure
Weight gain	Breast enlargement (gynaecomastia)
Hot flushes	Swelling (oedema)
Raised PSA and prostate enlargement	Raised PSA

The product information also warns that testosterone may raise blood pressure, may worsen existing sleep apnoea, and can cause fluid retention in people with heart, kidney or liver problems.

When to get urgent medical help

Contact a doctor straight away, or call 999, if you have:

• A cough, breathlessness or feeling unwell during or straight after an injection
• New or sudden swelling of the legs or ankles
• Signs of a serious allergic reaction, such as swelling of the face or difficulty breathing
• A prolonged, painful erection

This is not a full list. Always read the Patient Information Leaflet that comes with your medicine, and report suspected side effects through the MHRA Yellow Card scheme.

TRT and Fertility

Every TRT product we reviewed carries the same warning: testosterone can suppress sperm production. It works by lowering the body's own LH and FSH signals, and sperm count can fall significantly, sometimes to near zero.

After stopping TRT, sperm production may recover, but recovery is not guaranteed and can take months to years. If you want children now or in the future, talk to your prescriber before starting treatment. Options such as sperm banking can be discussed. Read our full guide to TRT and fertility.

TRT Blood Tests and Monitoring

Regular monitoring is a standard part of safe TRT. The product information for these medicines sets out checks of:

• Testosterone levels, timed to the product (for example, at the end of a Nebido injection interval, or before the morning application of Testogel)
• Haemoglobin and haematocrit, because testosterone can raise red blood cell levels
• Prostate checks and PSA, at least once a year, and more often in older men or those at higher risk
• Liver function and blood lipids during long-term treatment
• Blood pressure

In practice, many prescribers check bloods at baseline, at around 3 months, at 6 months, and then annually once stable. Your prescriber will set the schedule that is right for you.

Who Should Not Take TRT?

According to the product information, testosterone must not be used by people with:

• Known or suspected prostate cancer or breast cancer
• Current or past liver tumours (listed for Nebido)
• An allergy to the medicine or its ingredients, including peanut or soya for Sustanon

Tell your prescriber about any heart, kidney or liver problems, high blood pressure or sleep apnoea before starting.

Is Testosterone a Controlled Drug in the UK?

Yes. Testosterone is an anabolic steroid. It is a Class C drug under the Misuse of Drugs Act 1971 and Schedule 4 Part 2 under the Misuse of Drugs Regulations 2001. In practice this means:

• It can only be supplied against a valid prescription from a UK-registered prescriber
• Prescriptions are valid for 28 days from the date on the prescription
• Each supply needs a valid prescription in place
• It must never be bought from gyms, websites or social media sellers without a prescription. These products cannot be checked for safety and may be counterfeit

NHS vs Private TRT Prescriptions

TRT can be prescribed through the NHS or privately by a UK-registered prescriber, such as a GP, endocrinologist, or a private men's health or TRT clinic. Pharmazon HomeCare accepts both NHS and private prescriptions. With a private prescription, you pay for the medicine itself, and clinic fees are separate.

See our private TRT pharmacy page for more on how private prescriptions are handled.

TRT Prescription Delivery in the UK

Many patients prefer TRT prescription delivery to collecting in person, particularly on long-term treatment where supply has to line up with each injection interval or gel pack.

How Pharmazon HomeCare dispenses your TRT prescription

1. Your prescriber issues a valid prescription, from your GP, specialist or private TRT clinic.
2. The prescription reaches us. Clinics can send it to us directly.
3. A GPhC-registered pharmacist checks it, including the prescriber, product, dose, quantity and the 28-day validity.
4. We confirm stock and contact you if there is a query.
5. Your medicine is delivered by tracked delivery in plain, tamper-evident packaging, with same-day delivery available in London and next-day delivery across the UK.

Questions to Ask About Your TRT Medication

• Which TRT medicine and dose is right for me, and why?
• How often will I need my injection or gel, and how do I use it?
• What blood tests will I need, and how often?
• What side effects should I watch for?
• How will TRT affect my fertility, and what are my options?
• Can my prescription be delivered to my home?
• How do repeat prescriptions work so I do not run out?