Sustanon 250 & Nebido: UK TRT Dose Guide (2026)

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 vs Nebido: What UK Patients Are Prescribed

Calculating Your Sustanon 250 Dose

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

All volumes based on Sustanon 250 at 250mg/mL.

NHS vs Private Sustanon Protocols

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.

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.

Ready to track your protocol?

• Smart reminders so you never miss a dose
• Progress tracking with photos and weight
• Medication level curves for every compound

Get Regimen Free

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. Because of its very long half-life (~21 days), it does not offer the same stable levels as shorter-ester TRT.

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 can be injected intramuscularly (IM) or subcutaneously (SubQ):

• IM (gluteal muscle): Traditional NHS method. Deeper injection, larger volume tolerated.
• SubQ (abdomen or thigh): Increasingly preferred for weekly injections. Slower absorption gives slightly more stable levels for some patients. Uses smaller needles (25-27g, 16mm).

SubQ injection of Sustanon is not universally endorsed on NHS prescriptions but is widely practised in private TRT and generally well-tolerated.

Nebido is an IM-only injection due to its large volume (4mL). It should not be injected subcutaneously.

Getting TRT in the UK: NHS vs Private

Private TRT clinics with strong UK reputations include Balance My Hormones, Leger Clinics, and Optimale -- but 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.