Mounjaro injection doses: the complete UK schedule

What the licensed schedule actually looks like, and where it comes from

The six-dose structure is not a commercial choice. It reflects the titration pathway studied across the SURMOUNT clinical programme, which ultimately enrolled thousands of adults with obesity across its trials and informed the NICE appraisal of tirzepatide (TA1026) published in December 2024. Each 2.5 mg increment exists because the most common side effects (nausea, loose stools, indigestion) are dose-dependent and tend to be worst in the first week or two after a step-up. Starting at 2.5 mg keeps that experience manageable for most people.

From 2.5 mg, the prescriber typically moves patients up in 4-week steps: 5 mg, then 7.5 mg, a strength with its own clinical considerations you can read about on the Mounjaro injection 7.5 mg page, then 10 mg, and so on toward the maximum of 15 mg. But "typically" is doing a lot of work in that sentence. Some people stay comfortably at 5 mg or 7.5 mg for longer than four weeks because side effects are still settling. Others reach a dose where they are getting clear benefit and their prescriber decides not to push further. The SmPC permits staying at any dose that is well tolerated and effective, 15 mg is the ceiling, not the target for everyone.

Each Mounjaro KwikPen contains four doses of the same strength, covering one full month of weekly injections. What you receive is a single pen for that month's supply. If you order through a regulated UK pharmacy and the pen has been approved before noon on a weekday, it travels with DPD and arrives the next working day in a plain, unmarked box, nothing on the outside identifies what is inside.

The trial data behind the dose-response relationship

SURMOUNT-1 is the landmark study underpinning the licensed weight-management indication. Published in the New England Journal of Medicine, it randomised 2,539 adults with obesity over 72 weeks. Participants on 15 mg saw average body-weight reductions of around 20–21%, while those at 10 mg averaged somewhat less. The 5 mg arm produced meaningful results too, though the gap between low and high doses widened over time.

This dose-response pattern matters practically: it is why prescribers rarely keep someone at 2.5 mg beyond the first month unless there is a clinical reason, and why the upper doses attract more clinical interest for people with a higher starting BMI. At the same time, SURMOUNT-1 also captured tolerability data, the proportion of participants who discontinued because of gastrointestinal events was low but rose slightly at higher doses. That trade-off is exactly what a prescriber weighs when deciding whether to increase your 5 mg dose or hold for another month.

For context on cost as dose increases, the UK Mounjaro price comparison page sets out how private treatment pricing has moved since Eli Lilly adjusted its UK list price in September 2025.

Which dose strengths apply to you, and who decides

Two things determine which Mounjaro injection dose you start or move to: clinical assessment and your individual response. The licensed eligibility is BMI of 30 or above, or 27 or above with at least one weight-related condition such as high blood pressure, type 2 diabetes, high cholesterol or obstructive sleep apnoea. BMI thresholds are applied 2.5 kg/m² lower for some ethnic backgrounds under UK guidance. Meeting those criteria does not mean automatic approval at any particular dose, a prescriber reviews your full clinical picture.

For repeat prescriptions, the decision to increase a Mounjaro injection dose requires the prescriber to review evidence of your response at the current level. At nume this happens before every repeat order, which is why there are no subscriptions or auto-renewals. A named GPhC-registered Independent Prescriber reads your notes, not software. If the current dose is working well and tolerability is good, the prescriber may recommend staying there rather than stepping up. If side effects have been significant, they may suggest holding or, rarely, stepping back down.

Pages covering individual strengths in detail include the 2.5 mg starter pen and the 10 mg strength, which you can read about on the Mounjaro injection 10 mg page. For a broader look at the tirzepatide formulations available in the UK, the tirzepatide injection doses overview covers the clinical context across the full schedule.

Side effects by dose stage, and when to seek help

Gastrointestinal effects are the most commonly reported reactions across all Mounjaro injection dose levels: nausea, vomiting, diarrhoea, constipation and reflux feature most often, and they are generally at their peak in the days following a dose increase before settling over one to two weeks. Fatigue, headache and injection-site reactions are also reported. The NHS tirzepatide medicines page lists common and less-common side effects clearly.

More serious but infrequent effects include acute pancreatitis. Seek urgent medical attention for severe stomach pain that spreads to the back, with or without vomiting, this applies at any dose level. Gallbladder problems, allergic reactions and signs of significant dehydration from prolonged vomiting or diarrhoea also warrant prompt medical review. The MHRA's Yellow Card scheme at yellowcard.mhra.gov.uk is the place to report any suspected side effect, and reports from patients are genuinely valuable for ongoing safety monitoring.

Contraception is worth raising specifically because it is often overlooked: women taking oral contraceptives should add a non-oral method for the first four weeks of tirzepatide treatment and for four weeks after each dose increase, as absorption of the pill may be reduced. This applies regardless of the specific Mounjaro dose strength involved. Anyone with questions about managing their contraception, HRT or other medicines alongside treatment should raise them during their clinical consultation. You can find more detail about the clinical team behind those consultations on the clinical team profile.

If you are ready to discuss whether Mounjaro is clinically suitable for you and at which dose to begin, check your eligibility with a free consultation.