Does Semaglutide Work Better Than Tirzepatide? (October 2026)

01 · The verdict

Does tirzepatide work better than semaglutide? The short verdict

On trial averages, tirzepatide produced greater weight loss than semaglutide 2.4mg. SURMOUNT-5 randomised 751 adults to either medicine for 72 weeks. Average loss was 22.8 kg on tirzepatide versus 15.0 kg on semaglutide.¹⁵

"Better on average" is not "better for you". Both are effective, licensed treatments, and which suits you depends on your health profile, tolerance and prescriber advice, not the headline number alone.¹⁵

If you would like a prescriber to look at your own situation, you can start your free consultation. It is reviewed by a GPhC-registered prescriber, with no charge and no obligation.

02 · Side by side

Tirzepatide vs semaglutide: comparison table

Prices were checked 10 October 2026.

03 · Choosing

How to decide between tirzepatide and semaglutide

Start with what you need. If the highest average weight loss is the goal, SURMOUNT-5 showed greater average loss on tirzepatide, but your prescriber decides what suits you. For a 100 kg adult, the SURMOUNT-5 averages equate to roughly 20 kg versus 14 kg, but those are averages, not forecasts.¹⁵

Next, consider tolerance. In STEP 1, gastrointestinal side effects were reported by 74.2% of people on semaglutide 2.4mg versus 47.9% on placebo, and 7.0% stopped because of side effects.⁹ Tolerance is individual, and a medicine you can stay on is worth more than one you cannot.

Finally, consider your history. A prescriber will weigh your conditions, medicines and previous response. You can see all weight loss treatments we supply to compare options.

04 · Why one works better for you

Why semaglutide can work better for some people

Trial averages describe groups, not individuals. In SURMOUNT-5 more people lost at least 10% on tirzepatide (81.6%) than on semaglutide (60.5%), yet a proportion on semaglutide still lost large amounts.¹⁵ Trial averages do not predict your own result.

In STEP 1, 69.1% of adults on semaglutide 2.4mg lost at least 10% and 50.5% lost at least 15% over 68 weeks, and the average was 14.9%.⁹ In SURMOUNT-1, tirzepatide averaged 15% on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks.² These are separate trials, so do not read them as a head-to-head. Only SURMOUNT-5 compares the two directly.

If semaglutide is working better for you, practical reasons are likelier than a mystery: how well you tolerated each, how far up the dose ladder you got, and whether you stayed on treatment consistently.

05 · Realistic pace of results

How quickly do these medicines work?

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, and trials measured results at 72 weeks.

Three months in, a sensible expectation on a standard titration is mid single digits as a percentage of body weight, with wide individual variation. Slower early progress does not predict failure, because the dose you respond to may still be ahead of you. Plateaus of a few weeks are normal. A plateau is not a reason to double doses or add unlicensed products.

Your prescriber reviews response. If you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, they will discuss whether continuing or stopping is right for you.

06 · Downsides and who should be careful

What is the downside of semaglutide?

The commonest downside is gastrointestinal side effects. In STEP 1 these were reported by 74.2% on semaglutide 2.4mg versus 47.9% on placebo, and 7.0% stopped treatment because of side effects versus 3.1% on placebo.⁹

Who should avoid it, or what not to mix with it, is a prescriber decision based on your full history and medicines list. The one firm rule is never to run two GLP-1 medicines together.

If you have a concern, raise it with your prescriber. Report any new symptom through the Yellow Card scheme.¹⁹

07 · Switching between them

Switching from semaglutide to tirzepatide

There is no licensed direct conversion between semaglutide and tirzepatide. Switching is done under prescriber supervision: typically the previous medicine is stopped, a washout interval is observed, and Mounjaro is started at a dose your prescriber judges appropriate, often 2.5mg.¹¹ Never run two GLP-1 medicines together.

A prescriber may consider switching to tirzepatide if semaglutide was not tolerated or not working for you. A doctor might instead keep you on semaglutide because you are responding well or tolerating it well.

For deeper reading, see our guide on who responds better to semaglutide, when semaglutide works better and whether tirzepatide is better overall.

08 · Ozempic, supplements, newer drugs

Ozempic, "poor man's Ozempic" and newer drugs

Ozempic is semaglutide licensed for type 2 diabetes. It is not a UK weight-loss medicine, and prescribing it privately for weight loss is off-label. The licensed weight-management options are Mounjaro (tirzepatide) and Wegovy (semaglutide 2.4mg), so "Mounjaro vs Ozempic" for weight loss is really Mounjaro vs Wegovy.¹⁸

The "poor man's Ozempic" label is marketing for supplements such as berberine. They are not medicines, are not regulated for this use and have no comparable trial evidence. They are low-cost supplements with no clinical oversight, and dosing is not standardised.

Newer drugs are a separate question. Retatrutide has no UK licence and must not be combined with Mounjaro or sourced as a "research" peptide.¹ Our pages on retatrutide vs tirzepatide and CagriSema vs tirzepatide explain where they stand. If something promises faster results outside a licensed pathway, that is the warning sign.

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 · Tablets and NHS access

Tablets, and NHS access

There is no tablet form of Mounjaro. Two GLP-1 weight-loss tablets are now licensed in the UK: Wegovy tablets (oral semaglutide), approved by the MHRA in June 2026, and Foundayo (orforglipron), approved in August 2026.²⁰²¹ They have their own dosing, eligibility checks and trial results, so do not compare them with Mounjaro's results as if head to head. See current Wegovy tablet prices on the Wegovy product page.

On the NHS, Mounjaro is available 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.⁵ Many people who meet the licensed criteria choose regulated private treatment rather than wait.