What Works Better: Mounjaro or Wegovy? (October 2026)

01 · The verdict

Mounjaro vs Wegovy: which works better?

On average, tirzepatide produced greater weight loss than Wegovy 2.4mg in the first large head-to-head trial of the two. In SURMOUNT-5, adults on tirzepatide lost 20.2% of body weight over 72 weeks versus 13.7% on semaglutide 2.4mg.¹⁵ Averages do not predict your own result.

That does not make Wegovy a poor option. It is a licensed weight-management medicine with its own trial evidence, and some people tolerate or prefer it. Which suits you depends on your health profile, tolerance and prescriber advice.¹⁵

02 · Side by side

Mounjaro and Wegovy compared

The SURMOUNT-1 and STEP 1 figures come from different trials with different designs, so do not read them as a head-to-head. SURMOUNT-5 is the trial that compared tirzepatide directly with injected semaglutide.

03 · Choosing

What should decide your choice?

Your prescriber's assessment should decide, because the right option depends on your health profile and how you tolerate treatment. Useful questions to bring to a consultation:

• How much weight do you aim to lose, and over what timeframe? Both treatments are gradual and measured over many months.
• Have you tried either medicine before, and how did it go?
• Do you take other medicines, such as insulin or sulfonylureas? Doses may need adjusting because of low blood sugar risk.
• What does the monthly cost look like at the dose you are likely to need?

The Mounjaro pen is £169.99 per month at the 2.5mg starting dose. A new customer saves £40 on their first order with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.

Related guides: Which Is More Effective Mounjaro or Wegovy and Is wegovy or mounjaro better for weight loss.

04 · How they work

How the two medicines work differently

Tirzepatide activates two gut-hormone receptors at once, GIP and GLP-1. Together these help regulate appetite, slow how quickly the stomach empties and improve the way the body responds to insulin.¹

In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet. This dual action is what distinguishes Mounjaro from single-action GLP-1 medicines such as semaglutide (Wegovy).¹

Mechanism does not tell you how you will respond personally.

05 · Which mg works best

Which Mounjaro dose is right?

There is no single best dose: your prescriber sets it based on how you respond and tolerate it. In SURMOUNT-1, average losses were 15% on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone. Individual results vary.²

At 72 weeks, 85% of people on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of body weight. Half on 10mg and 57% on 15mg lost at least 20%.²

Everyone starts on 2.5mg once a week. That dose is about letting your body adjust, not weight loss itself. After at least 4 weeks it rises to 5mg, then in 2.5mg steps at minimum 4-week intervals up to 15mg. Many people settle at 5mg, 10mg or 15mg, and higher is not automatically better.¹

Cost scales with dose: £189.99 at 5mg, £274.99 at 10mg and £299.99 at 15mg per month, standard prices. A first year costs £2,399.88 if you stay on 5mg after your 2.5mg starting pen, up to £3,279.88 if you step up through every dose to 15mg, before discounts. A new customer's first order is £40 less and every later order £25 less.

06 · Pace of results

How fast do results come?

Weight loss on Mounjaro is gradual by design. The first weeks on 2.5mg are an adjustment phase and losses are usually modest. Most measurable progress builds from 5mg onward, month by month.¹

Trials measured results at 72 weeks, so think in months, not days, and judge progress by trend rather than individual weigh-ins. Early loss includes water weight.¹

If you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, your prescriber will discuss whether continuing or stopping is right for you.¹ For a related question see what works faster, Ozempic or Mounjaro.

07 · Switching

Switching from Wegovy to Mounjaro

There is no licensed direct conversion between semaglutide and tirzepatide, so switching is done under prescriber supervision. Typically the previous medicine is stopped, a washout interval is observed, and Mounjaro starts at a dose your prescriber judges appropriate, often 2.5mg and sometimes adjusted based on your history.¹

Never run two GLP-1 medicines together. Mounjaro must also not be combined with unlicensed research peptides such as retatrutide, which has no UK licence, or compounded copies. Anything promising faster results outside a licensed pathway is a warning sign.¹

08 · Ozempic and alternatives

Ozempic, tablets and other options

Ozempic is semaglutide licensed for type 2 diabetes, not a UK weight-loss medicine, and prescribing it privately for weight loss is off-label. The licensed weight-management options are Mounjaro and Wegovy, so Mounjaro vs Ozempic for weight loss is really Mounjaro vs Wegovy.¹⁸ See Ozempic or Mounjaro for weight loss.

There is no tablet form of Mounjaro. Wegovy tablets (approved by the MHRA in June 2026) and Foundayo (approved in August 2026) are different medicines with their own dosing and trial results; see the weight loss treatments page. Orlistat produces smaller average losses, and Saxenda is a daily injection. Berberine-style supplements are not medicines and have no comparable trial evidence.¹⁸

09 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹

10 · Safety and NHS

Safety, side effects and NHS access

Both medicines can cause side effects, and the safer choice for you depends on your history, so compare them with your prescriber. Our guide on which is safer, Wegovy or Mounjaro covers this in more detail. Tell your prescriber about any new or lasting symptom, and report any suspected side effect via the Yellow Card scheme.¹⁹

Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the primary-care rollout began in June 2025 with the highest-need groups first.⁴ Many people who meet the licensed criteria choose regulated private treatment rather than waiting. NHS access to Wegovy runs through specialist weight-management services; ask your GP. If you use the contraceptive pill, Mounjaro slows stomach emptying, which can reduce how well it is absorbed. Switch to a non-oral method, or add a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase. Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive.

Mounjaro is a prescription-only medicine supplied after an online consultation reviewed by a GPhC-registered prescriber, used alongside a reduced-calorie diet and increased physical activity.