Mounjaro in Preston: what the clinical evidence actually shows

What the SURMOUNT trials established, and why the numbers matter

The SURMOUNT-1 trial, published in the New England Journal of Medicine, randomised 2,539 adults with obesity but without type 2 diabetes across multiple treatment arms over 72 weeks. At the 15 mg maintenance dose, participants lost an average of around 20–21% of body weight; some analyses put the figure closer to 22.5%. Those are meaningful reductions in clinical terms, large enough to lower blood pressure, improve lipid profiles and reduce load on weight-bearing joints. The trial population included thousands of adults with conditions that will be recognisable to many people in Lancashire: hypertension, high cholesterol, obstructive sleep apnoea.

A subsequent head-to-head study, SURMOUNT-5, compared tirzepatide directly with semaglutide 2.4 mg (the active ingredient in Wegovy) over 72 weeks in 751 adults. Tirzepatide produced greater average weight loss. NICE's committee, reviewing that evidence in TA1026, noted indirect comparisons also favour tirzepatide. For a fuller look at how the two medicines compare, our tirzepatide overview works through the mechanism and trial record in more detail.

None of this tells any individual what they will lose, biology, diet, activity level and starting weight all interact. Trial results describe populations, not predictions. If progress stalls before you reach your goal, our page on what to do when your weight has stopped moving on Mounjaro works through the most common reasons and what can help. What the trials do establish is that the medicine's effect is substantial and consistent across a large, well-characterised dataset. That is the foundation any honest conversation about Mounjaro has to start from.

Who the Preston evidence base says this medicine is licensed for

UK licensing (granted by the MHRA based on the SURMOUNT data and the manufacturer's dossier) sets the formal eligibility frame. Adults aged 18 or over with a BMI of 30 or above qualify, as do those with a BMI of 27 or above if they have at least one weight-related condition: type 2 diabetes, prediabetes, high blood pressure, dyslipidaemia or obstructive sleep apnoea among the recognised examples. For some ethnic backgrounds, UK guidance applies BMI thresholds 2.5 kg/m² lower than the headline figures.

NICE's recommendation (TA1026, published December 2024 and updated September 2025) sets a higher bar for NHS access: BMI 35 or above plus at least one qualifying comorbidity, with a phased roll-out that began in June 2025. Private prescribing follows the licensed indications rather than the NICE thresholds, so the population who can access Mounjaro privately is broader, subject, always, to clinical assessment. NICE's appraisal of tirzepatide (TA1026) sets out the full NHS eligibility detail.

BMI alone has never been the whole picture. Prescribers look at medical history, current medicines, contraindications and what the evidence suggests about risk versus benefit for that person. That clinical judgement cannot be replaced by a postcode or a BMI calculator. Our page on Mounjaro prescribing covers how that assessment works in practice.

Side effects the evidence records, and when to seek help

The SURMOUNT programme documented a side-effect profile that is predominantly gastrointestinal, particularly in the weeks after starting or after a dose increase. Nausea, loose stools, constipation, reflux and burping are the most commonly reported. Fatigue, headache and injection-site reactions appear less often. Most participants found these effects settled within a couple of weeks; the slow titration schedule exists partly to give the body time to adjust.

Less common but more serious effects include gallbladder problems and, on 29 January 2026, the MHRA issued a Drug Safety Update specifically flagging acute pancreatitis as a known if infrequent risk across GLP-1 medicines. Severe, persistent stomach pain that spreads to the back (with or without vomiting) warrants urgent medical attention, not a wait-and-see approach. The same applies to signs of an allergic reaction or significant dehydration from prolonged vomiting or diarrhoea. Suspected side effects can be reported at the MHRA's Yellow Card scheme.

Mounjaro is not recommended during pregnancy, while breastfeeding, or for anyone trying to conceive. It is not licensed for under-18s. People with a history of medullary thyroid carcinoma, MEN2 syndrome or certain gastrointestinal conditions need to discuss those details with a prescriber before any treatment is considered. Cardiovascular effects are an active area of monitoring, and our page on Mounjaro and low blood pressure covers what the evidence shows for people concerned about that specific risk. Our page on how Mounjaro affects blood pressure covers what the evidence shows there.

Getting Mounjaro without a referral or a waiting list

For most people in Preston who meet the licensed criteria, the NHS route is likely to involve either a waiting list through specialist services or (as GP prescribing expands under the 2026/27 contract) checking whether their practice participates. Participation is optional, so availability genuinely varies practice to practice even within one city.

Private access through a GPhC-registered online pharmacy removes both the referral requirement and the queue. The legal route is the same as any other prescription medicine: a prescriber assesses your information, decides suitability, and issues a prescription if appropriate. At nume, that assessment is carried out personally by a GPhC-registered Independent Prescriber, a named clinician reads your consultation, not a piece of automated software. Orders placed before noon on a working day are dispatched the same day once approved and arrive the following working day via DPD, tracked and in plain packaging. It is worth knowing that getting the pen to your door before the school run pick-up is genuinely realistic if you start the process that morning.

Cost is a real consideration. Mounjaro's UK list price rose significantly in September 2025, and private prices typically range from around £149 to £375 per month depending on dose and provider, our Mounjaro cost page explains what drives that range and what a legitimate price should include. For an overview of weight-loss treatment options more broadly, our treatment overview sets the context. When you are ready to talk through your own situation, you can start a free consultation with our prescribers.