The new weight loss drug injections available in the UK

Step 1, understand which injection you might be prescribed and why it matters

The two licensed options are not interchangeable. Mounjaro activates two receptors (GIP and GLP-1) making it the only dual-agonist weight management medicine licensed in the UK. Wegovy works on the GLP-1 receptor alone. In the SURMOUNT-5 head-to-head trial, published in the New England Journal of Medicine in 2025, tirzepatide produced greater average weight loss than semaglutide 2.4mg over 72 weeks in adults with obesity.

From a practical standpoint, both are once-weekly injections delivered via a pre-filled pen. Mounjaro comes as the KwikPen; Wegovy has its own pen format, including a newer 7.2mg single-dose pen approved by the MHRA in April 2026. The different drug names and brands can be confusing at first glance, but the clinical distinction is straightforward: your prescriber recommends based on your full health picture, not on which pen looks simpler.

If you've seen Ozempic mentioned alongside these, it's worth knowing it contains the same active ingredient as Wegovy but is licensed for type 2 diabetes, not weight management. The two are not the same thing in a clinical context, and a prescriber will not use one as a substitute for the other.

Step 2, check whether you're likely to qualify before booking anything

Both medicines are licensed for adults with a BMI of 30 or above, or 27 and above if you have at least one weight-related health condition such as high blood pressure, high cholesterol, prediabetes, type 2 diabetes, or obstructive sleep apnoea. BMI is a starting point, not the whole picture; a prescriber looks at your current health, your medical history, and any medicines you already take.

The NHS recommends a quick check with the NHS BMI calculator before your consultation, it takes under a minute and gives you a number to discuss. Private eligibility thresholds broadly follow the licensed criteria above; NHS access is more narrowly phased, with Cohort 2 (BMI 35–39.9 with four or more qualifying conditions) activated in June 2026 under NHS England's rollout.

Mounjaro and Wegovy are not licensed for anyone under 18, and neither is recommended during pregnancy, breastfeeding, or when trying to conceive. Certain conditions (including a personal or family history of medullary thyroid carcinoma) require close discussion with a prescriber before treatment is considered.

Step 3, learn the injection technique before your first pen arrives

Both medicines are injected into the fatty tissue just under the skin, not into a muscle. The usual sites are the abdomen, the front of the thigh, or the outer upper arm. Rotating between sites each week prevents soreness building up at any one spot. Injection-site reactions are usually mild and short-lived.

Before injecting, cleaning the site with a fresh swab reduces the risk of infection. Alcohol swabs are easy to keep alongside your pen. After use, the needle goes straight into a sharps bin (not the household bin) and the pen is stored in the fridge between doses, at 2–8°C, per the Patient Information Leaflet.

The most common side effects reported in clinical trials were gastrointestinal: nausea, constipation, diarrhoea, reflux, and occasional burping. These are most noticeable after starting or after a dose increase, and most people find them manageable within the first couple of weeks. If you experience severe or persistent stomach pain that radiates to the back, seek urgent medical attention, pancreatitis is a known but infrequent risk, highlighted in a 2026 MHRA Drug Safety Update for GLP-1 medicines.

Step 4, get a prescription through a route you can verify

These are prescription-only medicines. The only legal way to obtain them in the UK is through a clinical assessment with a qualified prescriber who decides, based on your specific circumstances, whether treatment is appropriate. The safety of these injections depends heavily on the prescribing process being done properly.

When choosing an online pharmacy, check it is listed on the GPhC register at pharmacyregulation.org/registers. The MHRA has issued repeated warnings about counterfeit pens sold online without a prescription, including some containing insulin rather than the stated medicine. If a listing offers these medicines without a clinical consultation, that is a red flag, not a convenience.

At nume, a GPhC-registered Independent Prescriber reviews every consultation personally on the same day. There are no algorithms making prescribing decisions. For people weighing up where to access treatment, understanding what a consultation should actually involve is more useful than comparing prices alone. If you'd like to explore whether treatment is right for you, you can start a free consultation with our clinical team.