How to pick the right weight loss injection for you

Which medicine your health history points toward

This is a question our prescribers hear most weeks: "I've read about both, which one should I be on?" The honest answer is that your medical history does most of the deciding. A prescriber looks at conditions you already manage (type 2 diabetes, high blood pressure, high cholesterol, obstructive sleep apnoea) because both Mounjaro and Wegovy are licensed to help adults with weight-related comorbidities, not just those with a high BMI alone. If you have type 2 diabetes, tirzepatide also holds a licence for that indication, which can be relevant to how a prescriber thinks about your overall care.

There are also contraindications that close off one option or both. A personal or family history of medullary thyroid carcinoma or MEN2 is a reason prescribers approach GLP-1 medicines with particular caution. A history of pancreatitis matters too: the MHRA flagged acute pancreatitis as a known, infrequent but serious risk for GLP-1 medicines in a Drug Safety Update published in January 2026, and a prescriber factors that into any decision. These aren't checklist questions, they're the kind of detail a thorough clinical review exists to surface.

You can read a broader overview of what's involved in weight management treatment on the weight loss treatments overview, which covers how prescribers approach suitability across the licensed options.

How the two medicines differ in practice

Mounjaro is a dual GIP and GLP-1 receptor agonist, the only medicine of its kind licensed for weight management in the UK. Wegovy works on GLP-1 receptors only. That distinction matters because the two pathways interact with appetite, blood sugar regulation and gastric emptying in overlapping but not identical ways. In the SURMOUNT-5 open-label trial (72 weeks, 751 adults with obesity and no diabetes), tirzepatide produced greater average weight loss than semaglutide 2.4 mg head-to-head, as reported in the New England Journal of Medicine.

That said, no trial result is a prediction for any individual. Side-effect profiles are broadly similar, both cause mainly gastrointestinal symptoms such as nausea, diarrhoea, and constipation, especially early in treatment or after a dose increase. Some people tolerate one better than the other. If you've already tried one injection and moved to a new provider, a prescriber will want to see evidence of your current dose and how you've responded before making any changes. The weight loss injections page covers what each licensed medicine does in more detail.

Wegovy now also comes in a 7.2 mg maintenance dose, approved by the MHRA in January 2026, with a dedicated single-dose pen approved in April 2026, approaching tirzepatide's trial results at 15 mg. If you're considering tirzepatide specifically, our Waverly weight loss injection service is worth reading about before your consultation. Specific dose formats and availability are confirmed at consultation, not assumed in advance.

Cost, access and what each route actually involves

Both medicines are available privately through a regulated online pharmacy. Neither is broadly available on the NHS yet: Mounjaro is being phased into NHS primary care under strict eligibility criteria set out in NICE technology appraisal TA1026, and Wegovy remains largely within specialist weight management services. For most people reading this, a private prescription is the realistic current route.

Private treatment pricing varies by dose and provider. Since Eli Lilly raised Mounjaro's UK list price in September 2025, reported private prices for tirzepatide range roughly £149–£375 per month depending on dose and clinic. You can see how treatment pricing at nume is structured, including what's covered in a single transparent fee. Comparing headline prices between providers is worth doing carefully: what looks like a lower price sometimes excludes the consultation, prescription fee, delivery, or aftercare support. For a prescription medicine, the cheapest listing answers the wrong question, safe supply, clinical oversight, and genuine chain-of-custody matter more than a marginal price difference.

What the decision looks like at the point of assessment

Picking an injection isn't a self-service act, and that's not a bureaucratic inconvenience, it's what makes the treatment safe. A prescriber assessing you will consider your BMI (and the relevant threshold for your ethnic background, where lower thresholds apply under UK guidance), your weight-related conditions, your current medication list, and whether your goal is achievable within the licensed parameters.

The actual mechanics of injecting are a separate but practical concern. Both Mounjaro and Wegovy are weekly subcutaneous injections, given under the skin at the abdomen, thigh, or upper arm, rotated each week. If you want to understand how to use weight loss injections correctly, including storage, timing and technique, that guide is a helpful read before your consultation. Technique matters for both safety and comfort, and a prescriber or pharmacist can talk you through it.

Oral semaglutide (Wegovy tablets) became an option from June 2026, when the MHRA approved the first oral GLP-1 medicine licensed in the UK for weight management. For people who prefer not to inject, that's a genuine clinical alternative, though the decision between injection and tablet also falls within a prescriber's assessment, not a personal preference alone. The weight loss injection page explains what the injected forms involve day-to-day, which is useful context if you're weighing the two formats up.

Our prescribers review every consultation personally, your answers go to a clinician, not an automated filter. If you're ready to start that conversation, speak to our prescribers through a free consultation, with no obligation to proceed. You can also find a step-by-step guide on how to give a weight loss injection if you want to feel confident about the practical side before you begin.