Mounjaro vs Wegovy: Which Weight Loss Injection Is Right for You? (November 2026)

01 · The verdict

Mounjaro or Wegovy: how the choice works

No licensed medicine is best for everyone. On average, Mounjaro produced more weight loss than Wegovy in the only large head-to-head trial so far, and that is why many people ask for it first.³ Wegovy is still a very effective treatment, it costs less at the starting doses, and it now also comes as a daily tablet for people who would rather not inject.

• You might lean towards Mounjaro if you want the larger average weight loss seen in trials and are comfortable with a weekly injection.
• You might lean towards Wegovy if cost matters most early on, if you have done well on semaglutide before, or if you would like the option of moving to a tablet later.
• Either way, your health history, other medicines and how you tolerate side effects matter more than the headline number.

You do not have to decide alone. In the free consultation you can say which medicine you are interested in, and a GPhC-registered prescriber reviews your answers and recommends what is suitable.

02 · How to start

How to start either treatment

Choose Mounjaro or Wegovy, complete the free online consultation, and a GPhC-registered prescriber reviews it. If the treatment is suitable, our pharmacy dispenses it and sends it with free next-day tracked delivery. New customers get £40 off the first order with code FIRST40, repeat orders are £25 off with code DOSE25, and Subscribe & Save takes £40 off every order on injections.

Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only medicines, supplied only after an online consultation reviewed by a GPhC-registered prescriber. They are used alongside a reduced-calorie diet and more physical activity. Individual results vary. This page is information, not a substitute for medical advice.

03 · The key difference

What is the difference between Mounjaro and Wegovy?

Both medicines copy natural gut hormones that are released after eating. These hormones tell the brain you are full, slow the rate at which the stomach empties and help control blood sugar. The difference is how many of those signals each medicine copies.

• Wegovy contains semaglutide, which acts on the GLP-1 receptor.¹
• Mounjaro contains tirzepatide, which acts on both the GIP and the GLP-1 receptors.²

That second hormone pathway is the main reason researchers expected tirzepatide to produce more weight loss, and the trial results so far support that. It does not make Mounjaro the right choice for every person, but it explains why the two are not interchangeable and why your dose cannot simply be converted from one to the other.

Wegovy is made by Novo Nordisk and Mounjaro by Eli Lilly. Ozempic, which is often mentioned in the same breath, contains the same medicine as Wegovy but is licensed for type 2 diabetes rather than weight management. Our page on Mounjaro vs Ozempic covers that comparison.

04 · Head-to-head results

Mounjaro vs Wegovy for weight loss: what the trials show

The clearest evidence comes from SURMOUNT-5, the first large trial to compare the two directly. In SURMOUNT-5, 751 adults took tirzepatide or semaglutide 2.4mg for 72 weeks. Adults on tirzepatide lost on average 20.2% of body weight, versus 13.7% on semaglutide 2.4mg.³

The separate trials that led to each licence point the same way:

• In SURMOUNT-1, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.⁴
• In STEP 1, adults on semaglutide 2.4mg lost on average 14.9% of body weight over 68 weeks, compared with 2.4% on placebo.⁵

Trial averages hide a wide spread. Some people lose much more than the average and some much less, on either medicine. Both are effective, licensed treatments; which suits you depends on your health profile, tolerance and prescriber advice, not the headline number alone.

Putting the numbers in context

For someone weighing 100kg, a 13.7% loss is about 14kg and a 20.2% loss is about 20kg over a year and a half. That difference matters to many people, but so does staying on treatment. A medicine you can tolerate and afford for the long term often does better in real life than one you stop after a few months.

05 · Side effects compared

Mounjaro vs Wegovy side effects

The side effects are very similar, because both medicines slow digestion and reduce appetite. The most common side effects are digestive: nausea, constipation, diarrhoea, vomiting, indigestion and stomach pain.²¹ They are usually mild to moderate, most likely in the first weeks and after each dose increase, and tend to ease over time.

In STEP 1, gastrointestinal side effects were reported by 74.2% of people on semaglutide 2.4mg, compared with 47.9% on placebo.⁵

The rarer, more serious risks are shared too. Seek immediate medical help for severe, persistent stomach pain that may spread to your back (possible pancreatitis), pain in the upper right abdomen with fever or yellowing of the skin or eyes (possible gallbladder problems), or signs of a severe allergic reaction.⁶

Regulators have looked at whether GLP-1 medicines are linked to low mood or suicidal thoughts: in 2024 the MHRA concluded that the available evidence does not support a causal link, and it continues to monitor this closely.⁷ Tell your prescriber if your mood changes on either medicine.

06 · Doses compared

Mounjaro vs Wegovy doses and dose steps

Both medicines start low and increase slowly so your body can adjust.

For Mounjaro, after at least 4 weeks the dose rises to 5mg, then can step up by 2.5mg at intervals of at least 4 weeks, to a maximum of 15mg weekly.² For Wegovy, the dose steps up after 4 weeks on each of 0.25mg, 0.5mg, 1mg and 1.7mg, so the 2.4mg maintenance dose starts from week 17.¹ A higher 7.2mg Wegovy dose is also available in the UK for some people, at the prescriber's discretion.

The milligram numbers cannot be compared directly, because they are different medicines. 2.5mg of Mounjaro is not "ten times stronger" than 0.25mg of Wegovy. Each pen also holds four weekly doses, so one pen is a four-week supply for either medicine.² Our Mounjaro dose schedule shows every step in more detail.

07 · Cost compared

Mounjaro vs Wegovy cost in the UK

Wegovy is usually cheaper at the starting doses and Mounjaro costs more at the top end, so the gap depends on which dose you are on.

• Mounjaro with us: £169.99 for the 2.5mg pen, up to £299.99 for 15mg, at standard prices. That is £42.50 to £75.00 a week.
• Wegovy with us: from £99.99 per pen at the starting dose.

Across the UK pharmacies we track, Mounjaro pens run from £143.96 to £339.00 depending on dose and provider, checked on 10 November 2026. When you compare, look at what you will pay over several months rather than just the first pen, because the dose and therefore the price usually rise during the first few months.

Both are covered by the same offers with us: £40 off the first order with code FIRST40, £25 off repeat orders, and £40 off every order with Subscribe & Save on injections. For full dose-by-dose prices see our Mounjaro prices and Wegovy prices pages.

08 · Who each suits

Is Mounjaro or Wegovy better for you?

Your prescriber weighs several things, and the answer is different for different people.

Things that point towards Mounjaro

• You want the larger average weight loss seen in the head-to-head trial.
• You have tried semaglutide before and stopped losing weight on it.
• You are comfortable injecting once a week.

Things that point towards Wegovy

• Lower cost matters to you at the start.
• You have done well on semaglutide in the past and tolerated it.
• You would like the option of a daily tablet later, because Wegovy also comes as tablets.

Things that matter for both

Both are licensed for weight management in adults with a BMI of 30 or above, or 27 to under 30 with at least one weight-related condition, alongside a reduced-calorie diet and more physical activity.²¹ Neither is suitable in pregnancy or while breastfeeding, and your prescriber will take extra care if you have a history of pancreatitis, gallbladder problems or severe digestive disease. If you take the contraceptive pill, Mounjaro can make it less effective, because it slows stomach emptying, so you will need a barrier or non-oral method for four weeks after starting and after each dose increase.⁸

09 · The first months on each

What the first months look like on each medicine

The first few months are when the two medicines feel most different, because they step up on different timetables.

Mounjaro

You start on 2.5mg for at least four weeks, then usually move to 5mg. Some people notice less appetite within the first week or two; others feel little until 5mg. If you step up after four weeks on each dose, your first four pens (2.5mg to 10mg) cost £879.96 with us at standard prices, before discounts. Many people stay on 5mg or 7.5mg for longer than four weeks, which keeps the cost down.

Wegovy

You start on 0.25mg and move up every four weeks through 0.5mg, 1mg and 1.7mg, reaching 2.4mg from week 17.¹ The early doses are mainly there to help your body adjust, so weight loss in the first month is often modest.

On both

Side effects are most likely in the days after each increase. Eating smaller meals, stopping when you feel full, drinking enough fluid and going easy on fatty or fried food help most people through. If a dose does not suit you, your prescriber can keep you on it for longer rather than moving up.

10 · Questions to ask your prescriber

Questions to ask before you choose

If you are unsure which to start, these questions help you and the prescriber reach a decision that fits your situation:

• Have I used semaglutide or tirzepatide before, and how did I get on with it?
• Do any of my other medicines, including the contraceptive pill, affect the choice?
• What would the first six months cost on each, at the doses I am likely to need?
• Would I rather move to a tablet in future if one suits me?
• What should I do if side effects make it hard to step up?

There is no wrong answer to any of these. Writing them down before the consultation makes it easier to give the prescriber the information they need, and you can change your mind about which medicine you prefer at any point before it is dispensed.

11 · Switching between them

Switching between Mounjaro and Wegovy

People switch in both directions, usually because of side effects, cost or a weight-loss plateau. If you move from one to the other, the prescriber decides when to switch and which dose to start on. Because they are different medicines, your dose is not converted one-to-one, and the new medicine often starts at a lower step so your body can adjust.

Leave at least the normal one-week gap after your last injection before your first dose of the new medicine, unless your prescriber advises otherwise, and never take the two together. Tell the prescriber exactly which dose you were on and when you last injected, so they can plan your first dose safely.

If you are moving to us from another provider on the same medicine, our page on switching your Mounjaro provider explains how that works, and the first-order discount applies at any dose.

12 · Tablets as well as injections

Are Mounjaro and Wegovy available as tablets?

Two GLP-1 weight-loss tablets are now licensed in the UK: Wegovy tablets (oral semaglutide, made by Novo Nordisk), approved by the MHRA in June 2026, and Foundayo (orforglipron, made by Eli Lilly), approved in August 2026.⁹¹⁰

There is no tablet form of Mounjaro. Foundayo is made by the same company but is a different medicine. In the OASIS 4 trial, adults taking semaglutide 25mg tablets for 64 weeks lost on average 13.6% of their body weight, compared with 2.2% on placebo.¹¹ In the ATTAIN-1 trial, people taking the highest dose of orforglipron for 72 weeks lost on average 12.4% of their body weight, compared with 0.9% on placebo.¹²

Tablets suit some people who would rather not inject, but they come with their own rules. The Wegovy tablet must be taken on an empty stomach after fasting for at least 8 hours, with a sip of water, and you then wait at least 30 minutes before eating or drinking.⁹ Our guide to the Wegovy pill vs the injection compares the two forms.

13 · NHS and private

Mounjaro vs Wegovy on the NHS and privately

Both are available on the NHS for people who meet the NICE criteria, but access is limited. For Mounjaro, NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first.¹³¹⁴ Wegovy is also available on the NHS for people who meet the NICE criteria, mainly through specialist weight management services.

Privately, both are available from registered online pharmacies after a consultation. The licensed criteria are wider than the NHS criteria, which is why many people use a private prescription while they wait for, or do not yet qualify for, NHS treatment.

14 · Stopping treatment

What happens when you stop either medicine

Weight tends to come back after either medicine is stopped, because the appetite effect wears off. In SURMOUNT-4, people who stopped tirzepatide after 36 weeks regained on average 14% of body weight over the following year, while those who continued treatment lost a further 5.5% on average.¹⁵

That is why the choice between Mounjaro and Wegovy is also a choice about what you can stay on. Think about cost over a year or more, how well you tolerate it and whether you would prefer a tablet later. Building habits around food, activity and sleep while you are on treatment makes it easier to keep weight off if you stop or reduce your dose.