Which weight loss injections are available in the UK right now

Why the answer to 'which injection?' starts with how they work differently

Mounjaro and Wegovy both slow gastric emptying and reduce appetite, but they do so through different mechanisms. Mounjaro is a dual GIP and GLP-1 receptor agonist, the only medicine of its kind licensed for weight management in the UK. Wegovy acts on GLP-1 receptors only. In practice, both can produce meaningful weight reduction when used alongside a reduced-calorie diet and increased physical activity, but the trial data tells slightly different stories.

In the SURMOUNT-1 trial, tirzepatide produced average body-weight reductions of around 20–21% at the highest dose over 72 weeks, as published in the New England Journal of Medicine. The STEP 1 trial put semaglutide 2.4mg at around 15% average reduction over 68 weeks. A more recent head-to-head study (SURMOUNT-5, 2025) found tirzepatide produced greater average weight loss than semaglutide 2.4mg in adults with obesity and no diabetes. These are averages from clinical trials, your own result will depend on dose, duration, diet, activity and your individual biology. If you want to understand what the three weight loss injections are and how they compare, that context can help before you speak to a prescriber. A prescriber doesn't just pick the 'bigger number'; they weigh up your health history, any medicines you already take, and which option is licensed for your situation.

One practical note: if you use oral contraceptives, tirzepatide can temporarily affect how the pill is absorbed. Your prescriber will talk through adding a non-oral method for the first four weeks of treatment and for four weeks after each dose increase. That kind of nuance is exactly why clinical assessment matters before you start.

What the licensed eligibility criteria actually look like

Both medicines are licensed for adults. Mounjaro's UK licence covers a BMI of 35 or above alongside at least one weight-related health condition under the NICE recommendation, or BMI 30 and above under the SmPC for private prescribing. Wegovy's NICE recommendation similarly centres on BMI 35 or above with a weight-related comorbidity, and is restricted to a maximum two-year course within a specialist service. For private prescribing, the licensed threshold for both drops to BMI 27 or above when a qualifying condition (such as high blood pressure, type 2 diabetes, high cholesterol or obstructive sleep apnoea) is present.

Lower BMI thresholds apply for people from South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds under UK guidance, reflecting differences in health risk at a given BMI. Neither medicine is licensed for people under 18, during pregnancy, or while breastfeeding.

It's worth saying plainly: meeting the BMI number doesn't automatically mean a prescriber will approve treatment. They look at the whole picture, current medicines, medical history, and whether the benefits outweigh any risks for you specifically. That assessment is what distinguishes genuine weight loss injection services from anything operating outside the law.

NHS availability versus private routes, and what the difference means day to day

On the NHS, Mounjaro became available to some patients from June 2025, initially for those with a BMI of 40 or above and four or more qualifying conditions. Access is expanding in phases through 2026 and into 2027, but waiting times through specialist services can be long. GP prescribing under the new 2026/27 contract is optional, so availability varies significantly by area. You can read more about the NHS rollout timeline if that route is one you're exploring.

Private prescribing offers a faster, clinician-led alternative for people who are eligible but unwilling or unable to wait. Through a GPhC-registered online pharmacy, you can have a consultation reviewed by a qualified prescriber, typically the same day, with no referral required from a GP. If approved, the medicine arrives in plain, unbranded packaging via DPD, you get a tracking link and know exactly when to expect it. The pen itself is a pre-filled KwikPen; no drawing up, no measuring.

Cost is a real consideration. Since Eli Lilly revised its UK list price in September 2025, private Mounjaro has typically ranged from around £149 to £375 per month depending on the dose and provider. The full cost picture for weight loss injections is worth understanding before you compare services. A legitimate private price includes the prescription, clinical oversight and (depending on the service) aftercare. One that doesn't include those things isn't a bargain; it's a gap in your safety net.

What to check before starting either treatment

Whichever medicine a prescriber recommends, there are a few things to understand going in. Both Mounjaro and Wegovy are Black Triangle medicines, meaning the MHRA continues to monitor them actively as newer treatments. Side effects are predominantly gastrointestinal, nausea, loose stools, constipation and reflux are common, particularly after starting or moving to a higher dose. They tend to settle as your body adjusts, but severe or persistent stomach pain that spreads to your back needs urgent medical attention, as it can signal pancreatitis.

You'll dispose of used pens in a sharps container rather than the household bin. Both medicines are stored in the fridge; the exact room-temperature window if you're travelling or a pen has been left out is detailed in the Patient Information Leaflet, check that rather than relying on a rough estimate from any source including this one.

If you'd like to explore whether either of these licensed weight loss injections is suitable for you, the next step is a proper clinical conversation. Patients based locally can find out more about accessing weight loss injections in Newcastle through our service. At nume, that means a free consultation reviewed by a GPhC-registered Independent Prescriber, a real clinician reads your answers, not a decision tree. Speak to our prescribers to find out where you stand.