What are the approved weight loss injections available in the UK?

Which injections carry UK approval for weight loss, and what makes them different?

Mounjaro and Wegovy are the two medicines licensed by the MHRA specifically for weight management in adults. They belong to the same broad family (both act on GLP-1 receptors involved in appetite signalling and the rate at which the stomach empties) but they are not identical. Wegovy contains semaglutide and targets a single receptor pathway. Mounjaro contains tirzepatide and activates two pathways simultaneously: GLP-1 and GIP. That dual mechanism is what sets Mounjaro apart; if you're researching how a weight loss med injection like this works at a pharmacological level, our dedicated page goes into the detail behind each approved option.

In clinical trials, both medicines produced meaningful weight loss compared with placebo. The STEP 1 trial, published in the New England Journal of Medicine, found semaglutide 2.4mg reduced average body weight by roughly 15% over 68 weeks. The SURMOUNT-1 trial, involving 2,539 adults, found tirzepatide at 15mg produced average reductions of around 20–21% over 72 weeks. A head-to-head comparison (the SURMOUNT-5 trial, published in 2025) found tirzepatide produced greater average weight loss than semaglutide 2.4mg. Which medicine suits a given person is a clinical question that depends on their health history, other medicines, and preferences.

Wegovy has a higher dose option too: a 7.2mg weekly pen was approved by the MHRA in April 2026, with trials suggesting average weight loss of around 20.7% at that strength over 72 weeks, narrowing the gap with tirzepatide's highest dose considerably.

Who qualifies for an approved weight loss injection in the UK?

The licensed criteria are set out in each medicine's Summary of Product Characteristics, verified against NHS guidance on tirzepatide. In broad terms, adults with a BMI of 30 or above qualify, as do those with a BMI from 27 upward if they have at least one weight-related condition, examples include type 2 diabetes, high blood pressure, raised cholesterol, obstructive sleep apnoea, or established cardiovascular disease. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance; a prescriber considers this alongside everything else.

NICE has recommended both medicines through its technology appraisal process, though the NHS criteria attach additional conditions around comorbidities and service settings. If you're considering a weight loss injection through a regulated private pharmacy, our page explains how that route works for people who meet the licensed eligibility but don't qualify under NHS criteria yet, or who prefer not to wait. If you want to understand the application process in more detail, our guide on how to apply for weight loss injections covers the steps involved.

A BMI figure alone never guarantees a prescription. The prescriber also looks at contraindications (including a personal or family history of medullary thyroid carcinoma, a history of pancreatitis, and certain gastrointestinal conditions) as well as current medicines and overall health. These injections are not licensed for anyone under 18, and they are not recommended during pregnancy, while breastfeeding, or for people trying to conceive.

What side effects are common with approved weight loss injections?

The side-effect profile is similar across both medicines and is led by the gut. Nausea is the most commonly reported symptom, followed by diarrhoea, constipation, vomiting, indigestion, and burping. Fatigue, headache, and reactions at the injection site are also reported. The good news is that for most people these effects are most noticeable at the start of treatment or just after a dose increase, and they ease as the body adapts, usually within a week or two.

There are less common but more serious effects to be aware of. Acute pancreatitis is a known risk: the MHRA issued a Drug Safety Update in January 2026 specifically highlighting this across GLP-1 medicines. Severe stomach pain that radiates to the back, with or without vomiting, warrants urgent medical attention. Gallbladder problems, allergic reactions, and signs of significant dehydration from prolonged GI illness are other reasons to contact a doctor promptly. You can report any suspected side effect through the MHRA Yellow Card scheme.

On the practical side: the pens are pre-filled and come with an auto-injection mechanism, so you do not draw up a dose yourself. Injection sites are the abdomen, thigh, or upper arm, rotated each week. Both medicines require refrigeration between uses; the Patient Information Leaflet in your pack sets out the exact storage windows. Our page covering weight loss injections in general also runs through the practical aspects of using and storing the pens, which is worth reading alongside the leaflet in your pack. If you have questions about travelling while on treatment, our page on travelling with weight loss injections has the practical detail.

What does treatment through a regulated UK pharmacy actually involve?

Obtaining an approved weight loss injection legally means obtaining a prescription, full stop. A registered prescriber must review your medical history, verify your identity, and confirm you meet the clinical criteria before any medicine is dispensed. This is not a formality; it is the legal basis on which these prescription-only medicines can be supplied, and the process that keeps them safe.

At nume, that review is carried out the same day by a GPhC-registered Independent Prescriber, a real clinician reading your answers, not automated software processing a form. Weight is verified on a short video call. Once approved, orders placed before 12pm are dispatched the same day, arriving by DPD the next working day in plain, unbranded packaging. Your tracking link comes through on your phone while the box is still in transit. You can read more about how our service is structured, or explore an overview of the weight management treatments we offer.

Our pharmacy holds GPhC premises registration 9012878, verifiable directly on the GPhC register. Every repeat order goes through the same clinical review, there are no auto-renewals or subscriptions. If you want to understand what a typical consultation covers before you begin, our page on weight loss injection eligibility and the review process is a useful starting point, and our frequently asked questions page covers a broader range of queries. When you're ready to take the next step, you can speak to our prescribers through a free consultation.