Verification note: Coverage, eligibility criteria, and pricing for UK health services change frequently. Information here reflects publicly available data as of May 2026. Always verify current NHS access and clinical thresholds at nice.org.uk or nhs.uk before making treatment decisions.
If you are on testosterone replacement therapy in the UK, you are almost certainly prescribed either Sustanon 250 or Nebido — not testosterone cypionate or enanthate, which are the US standard but rarely used on NHS prescriptions. This guide covers how to calculate your dose, understand your injection schedule, and track your protocol for both of the UK’s most common TRT medications.
Sustanon 250 dose for TRT (quick answer): The standard NHS dose is one 250mg ampoule every three weeks. Private clinics and optimised protocols usually run a similar or slightly higher total, but split it into smaller, more frequent injections — commonly around 125mg a week (half an ampoule) — because steadier levels beat one big dose every few weeks. Sustanon is pre-mixed at 250mg per 1mL ampoule, so the maths is simple: 1mL = 250mg, 0.5mL = 125mg. Your exact amount depends on your bloods and how you feel, which is what the UK TRT dose calculator works out for you.
Before Your First Sustanon Injection: Check for Peanut Allergy
Sustanon 250 is dissolved in arachis oil, which is peanut oil. The SmPC lists it as an excipient and contraindicates the product in anyone allergic to peanuts. Because peanut and soya allergy can travel together, it also says people with a soya allergy should avoid Sustanon 250.
“Hypersensitivity to the active substance or to any of the excipients listed in section 6.1, including arachis oil (refined). Sustanon 250 is therefore contraindicated in patients allergic to peanuts or soya”
If either allergy applies to you, tell your prescriber before you are given Sustanon and ask about an alternative ester. Nebido is not affected: it is suspended in benzyl benzoate and refined castor oil, with no arachis oil.
Source: Sustanon 250 SmPC, sections 4.3, 4.4 and 6.1.
Sustanon 250 vs Nebido: What UK Patients Are Prescribed
| Sustanon 250 | Nebido | |
|---|---|---|
| Full name | Testosterone (propionate, phenylpropionate, isocaproate, decanoate) | Testosterone undecanoate |
| Concentration | 250mg/mL (1mL ampoule) | 250mg/mL (4mL ampoule = 1,000mg) |
| Typical frequency | Every 3 weeks (NHS) / every 1-2 weeks (optimised) | Every 10-14 weeks |
| Standard NHS dose | 1mL (250mg) every 3 weeks | 1,000mg every 12 weeks |
| Common private dose | 0.5mL (125mg) weekly or 1mL every 2 weeks | 1,000mg every 10-12 weeks |
| What the SmPC says about duration | Peak plasma testosterone at about 24-48 hours; levels return to the lower limit of the normal range in about 21 days. No single half-life is published for the blend | Depot release characterised by a half-life of 90 (plus or minus 40) days |
| Who it’s best for | Patients who want more frequent, stable dosing | Patients who prefer infrequent injections |
Sustanon 250 Dosage for TRT: NHS vs Private
Sustanon 250 comes as a 1mL ampoule containing 250mg of testosterone across four esters. Because it is pre-mixed, the dose calculation is simpler than variable-concentration vials:
- 1 full ampoule = 1mL = 250mg
- Half ampoule = 0.5mL = 125mg
If you are injecting weekly (common in private TRT), you will typically draw 0.5mL (125mg) per week from a 1mL ampoule, giving you two weekly injections per ampoule.
Sustanon 250 Dose Reference Table
| Weekly Dose | Per Injection (2x/week) | Per Injection (1x/week) | Volume |
|---|---|---|---|
| 125mg | 62.5mg | 125mg | 0.25mL / 0.5mL |
| 175mg | 87.5mg | 175mg | 0.35mL / 0.7mL |
| 200mg | 100mg | 200mg | 0.4mL / 0.8mL |
| 250mg | 125mg | 250mg | 0.5mL / 1.0mL (full ampoule) |
All volumes based on Sustanon 250 at 250mg/mL. To work out the per-injection volume for your own prescribed dose, use the UK TRT calculator.
NHS vs Private Sustanon Protocols in Practice
The standard NHS Sustanon protocol (250mg every 3 weeks) is widely considered suboptimal by endocrinologists — the injection frequency causes significant peak-and-trough testosterone fluctuations. Many NHS patients experience high levels in the first week and low levels by week 3.
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Private TRT clinics in the UK commonly prescribe weekly or twice-weekly Sustanon injections at lower doses (125-175mg/week split into 1-2 injections). This produces more stable testosterone levels and is closer to how testosterone enanthate and cypionate are used in the US.
If you are on the NHS 3-weekly protocol and experiencing mood instability, low energy, or libido issues in the third week, this is a recognised issue — worth discussing with your GP or an endocrinologist.
Calculating Your Nebido Dose
Nebido is a long-acting testosterone undecanoate injection — 1,000mg in 4mL, administered every 10-14 weeks. The apparent serum half-life of the curve you see after a shot is around 34 days (castor-oil depot release), which is why doses are spaced 10-14 weeks apart — but the curve still drifts down noticeably before the next injection.
There is no volume to calculate with Nebido — it is always the full 4mL ampoule (1,000mg). The only variable is how frequently your doctor schedules your injections:
- Every 12 weeks: Standard NHS schedule. Testosterone often drops below optimal in weeks 10-12.
- Every 10 weeks: More common in private prescriptions; maintains more consistent levels.
- Loading dose: Most protocols include a second injection 6 weeks after the first to build up initial levels.
Is Nebido Right for You?
Nebido suits patients who strongly prefer infrequent injections and do not mind some level variation. It is less suitable for men who want fine-tuned, stable testosterone levels — Sustanon injected weekly produces significantly more consistent levels.
Many patients who start on Nebido switch to Sustanon (or testosterone enanthate prescribed privately) after experiencing the end-of-cycle dip.
Injection Site Guidance for UK TRT
Sustanon 250 is licensed for deep intramuscular injection only. The SmPC is explicit: “Sustanon 250 should be administered by deep intramuscular injection.” That is the route your prescriber is working from, and it is the one to assume unless they tell you otherwise.
- IM (gluteal muscle): The licensed route and NHS standard. Deeper injection, larger volume tolerated.
- SubQ (abdomen or thigh): Off-label. Some private TRT patients on weekly protocols do inject subcutaneously with smaller needles (25-27g, 16mm), but this sits outside the product licence. It is a conversation to have with your prescriber, not a switch to make on your own.
Nebido is strictly intramuscular. The SmPC says: “Nebido is strictly for intramuscular injection. Care should be taken to inject Nebido deeply into the gluteal muscle following the usual precautions for intramuscular administration.” It adds two things people miss: the injection must be given very slowly, over two minutes, and the ampoule or vial is for single use only, with the contents injected immediately after opening.
Getting TRT in the UK: NHS vs Private
| NHS | Private | |
|---|---|---|
| Cost | Free (prescription charges apply) | GBP 100-300/month depending on clinic |
| Medication | Usually Sustanon or Nebido | Sustanon, Nebido, or imported enanthate |
| Frequency | Often 3-weekly (Sustanon) or 12-weekly (Nebido) | Optimised to weekly or EOD |
| Monitoring | Annual bloods typically | More frequent, more comprehensive |
| Waiting time | Often 6-18 months via GP referral | 1-4 weeks |
| Prescribing criteria | Strict (clinical hypogonadism) | Broader |
Private TRT clinics differ in cost and protocol options, so as with any medical decision, research your provider carefully.
Tracking Your UK TRT Protocol
Whether you are on NHS Sustanon or private weekly injections, keeping a dose log is essential — especially if you are trying to correlate your protocol with bloodwork, energy, or mood.
Regimen supports Sustanon 250 and Nebido alongside all common testosterone esters. The half-life visualiser shows how testosterone levels from a Sustanon blend behave between doses, which is especially useful for visualising the difference between the NHS 3-weekly protocol and a weekly split.
Frequently Asked Questions
What’s the dose of Sustanon 250 for TRT?
The standard NHS dose is 250mg (one 1mL ampoule) every three weeks. Private and optimised protocols usually run a similar or slightly higher total split into weekly or twice-weekly injections — often around 125mg a week — for steadier levels between doses. Your exact figure is set by your bloods and prescriber.
How much Sustanon per week for TRT?
Optimised UK protocols commonly run around 100-150mg a week, which is roughly 0.4-0.6mL of a 250mg/mL ampoule split into one or two injections. The NHS default is 250mg every three weeks (about 83mg/week averaged), which is why many private clinics move to weekly dosing for stability.
What is Sustanon 250?
Sustanon 250 is a blend of four testosterone esters: propionate (30mg), phenylpropionate (60mg), isocaproate (60mg), and decanoate (100mg), in a 1mL ampoule. Total: 250mg of testosterone. It is the most commonly prescribed TRT medication in the UK. It is dissolved in arachis oil (peanut oil), so the SmPC contraindicates it in anyone allergic to peanuts and says people with a soya allergy should avoid it too.
Can I use the standard TRT dose calculator for Sustanon?
Yes — Sustanon 250 is 250mg/mL, so enter 250mg/mL as your concentration in the TRT dose calculator. The calculator works for any concentration.
Why does my GP prescribe Sustanon every 3 weeks but I’ve read weekly is better?
The 3-weekly NHS schedule is based on older prescribing guidance. Many endocrinologists and TRT specialists now prefer weekly or twice-weekly injections of lower doses because they produce more stable testosterone levels. This is an area where private TRT care in the UK has diverged from NHS standard practice.
Can I inject Sustanon subcutaneously?
Sustanon 250 is licensed for deep intramuscular injection only. That is what the SmPC specifies. Some UK TRT patients on weekly protocols do inject it subcutaneously, but that is off-label, so treat it as something to raise with your prescriber rather than a change to make on your own.
Is testosterone cypionate available in the UK?
Testosterone cypionate is not licensed in the UK and is not typically available on NHS prescription. Some private clinics can source it, but Sustanon and enanthate are far more common. If you are from the US and moving to the UK, your prescription will likely change.
What’s the difference between Sustanon and Nebido?
Sustanon is a short-to-medium ester blend injected every 1-3 weeks. Nebido is a very long-acting ester (1,000mg) injected every 10-14 weeks. Sustanon gives more stable levels with frequent dosing. Nebido is simpler but has more peak-and-trough variation.
Regimen supports Sustanon 250 and Nebido alongside all common testosterone esters. Track your UK TRT protocol, visualise half-life curves, and correlate symptoms with your dosing schedule. Free for one compound.
Regimen is a tracking tool, not a medical service. We do not provide medical advice. Always consult your healthcare professional before starting, changing, or stopping any medication protocol.
