How much tirzepatide do you start with, and what does that mean for cost?

What the prescribing guidance says about the first dose of tirzepatide

NICE's appraisal of tirzepatide (TA1026), published in December 2024, confirms the medicine is initiated at 2.5 mg once weekly. The dose is then titrated (typically in four-week steps) by the prescribing clinician, progressing through 5 mg, 7.5 mg, 10 mg, 12.5 mg and up to 15 mg depending on how well the treatment is tolerated and how weight loss is progressing. The NHS page on tirzepatide sets out the same schedule.

The starting pen is not a therapeutic dose in the conventional sense. Its job is adjustment: the gradual introduction reduces the nausea and digestive disruption that higher doses can produce if reached too quickly. Many people find the first four weeks fairly comfortable; others experience more noticeable side effects that settle with time. Neither pattern tells you much about how the medicine will ultimately work for you.

SURMOUNT-1, the pivotal phase-3 trial published in the New England Journal of Medicine, recruited 2,539 adults with obesity and found that participants on the highest dose achieved an average body-weight reduction of around 20–21% over 72 weeks. That result comes after a full titration sequence — not from a starter pen held at 2.5 mg. It matters for cost conversations because reaching those results involves spending several months at lower doses first, each priced separately.

How UK private pricing is structured around dose

Private weight-loss treatment in the UK is priced per pen, and each pen covers four weekly doses at one strength. A 2.5 mg starter pen costs less than a 15 mg maintenance pen. The gap is substantial: following Eli Lilly's UK list price revision in September 2025, the highest-dose pen's list price rose to around £330, up from roughly £122 before that change. Private providers set their own prices above list, so the figure a patient pays varies by provider and by dose, typically in a range reported broadly as £149–£375 per month depending on where you are in your titration. Those figures are hedged because they shift, and because the dose you're prescribed determines where in that range you sit.

For a fuller picture of how Mounjaro private pricing works across the dose range, our Mounjaro price guide sets out the market context in more detail.

One practical point about timing: many people start treatment at the beginning of the month to align with payday, or hold off until a Monday so the 12 pm dispatch cut-off works in their favour for a same-week delivery. There is no clinical reason to prefer one day of the week, but it does affect when the pen arrives. Worth thinking through if your schedule is tight.

What headline prices often leave out

A quoted per-pen price is not always the full picture. Some providers charge a separate consultation fee before issuing a prescription; others add a prescription charge on top of the pen price, or bill for delivery. Aftercare (the clinical support that should accompany a prescription medicine) may be billed as an add-on or simply absent. Dose-review support, which matters when you move from 2.5 mg to 5 mg and again at each subsequent step, can carry a further charge.

None of those costs are disclosed until you are already committed to a provider, which makes comparing headline figures difficult. The question is not just what the pen costs at the starting dose, but what the total cost of supervised treatment looks like over three to six months of titration. Our full cost breakdown for tirzepatide in the UK covers what a complete month of private treatment typically involves.

It is also worth knowing that these medicines are prescription-only. Any seller offering tirzepatide without a clinical assessment attached to the price is not operating within the law. The MHRA has warned publicly about counterfeit weight-loss pens sold online and, following raids through 2024 and 2025, seized approximately 20 million doses of illegally traded weight-loss medicines worth around £45 million, some fake pens containing harmful substitutes. A price that looks unusually low is a reason to check, not a reason to proceed. You can verify any UK online pharmacy on the GPhC register before placing an order.

How nume prices the starter dose and what that includes

We are not the cheapest option in the UK private market. That is a deliberate position. A real clinician (a GPhC-registered Independent Prescriber) reads your consultation responses and reaches a decision the same day. Identity is verified. Weight is confirmed. If you are transferring from another provider, evidence of your current treatment is reviewed before any dose is continued or increased. None of that infrastructure is optional for us, and it does add to what we charge.

What the price includes: the consultation, the prescription, the medicine, and free next-working-day delivery by DPD. There are no aftercare charges, no subscription and no auto-renewal. Every repeat order goes through a fresh clinical review, and patients moving up to the 10 mg pen can find guidance on how much water to mix with 10 mg tirzepatide to help them prepare their doses accurately. If you are specifically using bacteriostatic water, our guidance on how much bac water to mix with 10 mg tirzepatide and on how much bac water to mix with 30 mg tirzepatide covers the higher strengths too, while our broader page on how much bac water to mix with tirzepatide brings all the reconstitution information together in one place. Current treatment pricing (including what the 2.5 mg starter pen costs through nume) is listed on our treatment page, alongside the eligibility criteria our prescribers assess against.

For context on what our clinical team checks at each stage, our lead prescriber's profile gives a clearer picture of the oversight behind every prescription. And if you want a broader overview of weight-loss treatment options available through a regulated UK pharmacy, that page covers all the medicines we prescribe.

Price is a reasonable thing to compare. For a prescription medicine, though, it is not the measure that keeps you safe. A regulated supply chain, clinical oversight at every dose step, and a genuine prescriber who can be held to account, those are the factors that matter most when you are deciding where to start treatment.