Mounjaro vs Wegovy - which medication is right for you

Mounjaro (tirzepatide) and Wegovy (semaglutide) are the two most effective weight-loss medications currently available in the UK. Both are weekly injections, both are MHRA-licensed for weight management, and both will work for the majority of patients who take them. But they are not identical, and the right choice depends on factors we work through together in your first consultation.

This article explains what is actually different between them, and how we make the call.

Effectiveness

This is the question everyone asks first. In the two largest head-to-head trials (SURPASS-2 and the SURMOUNT programme):

Mounjaro at its maximum 15mg dose produces an average weight loss of around 22.5 percent of starting body weight after 72 weeks of treatment.

Wegovy at 2.4mg produces an average weight loss of around 15 percent over the same period. The newer 7.2mg Wegovy dose (MHRA-approved January 2026) achieves 20.7 percent.

At the maintenance doses currently most commonly prescribed, Mounjaro produces somewhat greater weight loss than Wegovy, but the gap has narrowed considerably since the higher-dose Wegovy became available. For most patients the difference is a few extra kilograms over a year, not a transformative gap.

Side effect profile

Both medications share the same family of side effects, dominated by gastrointestinal upset during titration. Nausea, constipation, and occasional vomiting affect most patients at some point in the first twelve weeks and then settle.

There are some differences that matter for specific patients.

Wegovy tends to have marginally more reports of nausea at comparable effectiveness doses.

Mounjaro tends to have marginally more reports of mild diarrhoea or loose stool.

Both share the small but real risks of gallstone disease, pancreatitis, and thyroid C-cell tumours (the last of which has only been demonstrated in rats, not in humans, but is still included as a theoretical contraindication in patients with a personal or family history of medullary thyroid cancer or MEN2).

If you have a sensitive stomach or a history of reflux, the choice between them is often decided by which side effect profile you would rather work with.

Cost

As of early 2026, UK private pricing varies significantly by provider. The underlying list prices from the manufacturers matter:

Mounjaro (Eli Lilly) list price rose sharply in September 2025. The 15mg maintenance dose now lists at around £330 per four-week pen before the provider's margin and fees.

Wegovy (Novo Nordisk) pricing has been more stable. The 2.4mg dose typically runs £220-260 per month and the newer 7.2mg dose around £290-320.

At LoveMyLife your monthly care subscription includes your medication from our own pharmacy. You pay the same £245 per month regardless of which medication you are on or which dose you are at. Dose escalations inside a calendar month do not trigger additional charges.

Availability and supply

Both medications have been subject to intermittent supply disruption over the last two years, particularly at starting doses. Our in-house pharmacy gives us advance visibility of wholesale supply. If one medication is difficult to source we will tell you honestly and switch you or start you on the other, rather than leaving you waiting for three weeks.

Cardiovascular evidence

This matters if you have existing cardiovascular risk factors.

Semaglutide has specific evidence from the SELECT trial showing cardiovascular benefit in people with pre-existing cardiovascular disease and overweight or obesity. The MHRA licence now includes a cardiovascular benefit indication.

Tirzepatide's equivalent cardiovascular outcome trial (SURPASS-CVOT) is ongoing. Early signals are consistent with benefit, but the formal cardiovascular benefit indication has not yet been granted in the UK.

If you have had a heart attack, stroke, or documented coronary artery disease, Wegovy is currently the more conservative evidence-based choice.

Diabetes and pre-diabetes

If you have type 2 diabetes or significant pre-diabetes:

Mounjaro has the stronger glycaemic effect. HbA1c reductions on Mounjaro are typically 1.5-2.0 percent at maintenance dose, compared with 1.0-1.5 percent for semaglutide.

If your main goal is weight loss but your HbA1c is also in the 42-50 mmol/mol pre-diabetic range, Mounjaro gives you the dual benefit.

How we make the decision with you

In your first consultation we work through:

Your weight-loss goal and starting BMI.

Your cardiovascular risk (established disease or risk factors).

Your HbA1c.

Your personal and family medical history (thyroid, pancreatitis, gallstones).

Your preferences (any prior experience with these medications, your tolerance for side effects).

Your budget and whether you are paying for all twelve months up front or month by month.

In most cases either medication is reasonable. Our default recommendation for patients with BMI over 30 and no specific contraindication is Mounjaro at 2.5mg to start, with a plan to escalate over eight weeks to the effective dose. For patients with established cardiovascular disease, Wegovy. For patients who have tried one and not tolerated it, we switch to the other.

You are not locked in

Switching between the two during treatment is straightforward. If you start on Mounjaro and want to switch to Wegovy after three months, we do that at your next review with no additional assessment charge. Both medications come from our own pharmacy, so the switch happens in days, not weeks.

Ready to start?

If this article has made you think medication might help, the next step is a short consultation with one of our weight-management doctors.

Begin your consultation at this link. Online in 30 minutes, or in person at Westfield London.