Do Some People Respond Better to Semaglutide Than Tirzepatide? (October 2026)

01 · The short verdict

Who might do better on semaglutide, and who on tirzepatide?

On average, tirzepatide produced greater weight loss in the first large head-to-head trial, SURMOUNT-5. Both are effective, licensed treatments, and which suits you depends on your health profile, tolerance and prescriber advice, not the headline number alone.¹⁵

Semaglutide 2.4mg (Wegovy) is an effective licensed alternative, and your prescriber decides which suits you. The wider question of which medicine works better has the same honest answer: it depends on the person.

The trial columns come from SURMOUNT-5, 751 adults followed for 72 weeks.¹⁵ The table shows something important for your question: even in the group with the lower average, many people reached large losses. And in the group with the higher average, not everyone did.

02 · Decision factors

How to decide between them

Start with what you can actually tolerate and sustain. A medicine you can stay on for months at an effective dose will usually serve you better than one you stop after weeks. Talk through your medical history, previous experience with any GLP-1 medicine and your goals with a prescriber.

If you have not used either, the practical route is a free consultation, reviewed by a GPhC-registered prescriber, who can discuss which licensed option fits. You can start your free consultation with no obligation. If you are leaning towards tirzepatide, the Mounjaro pen starts at £169.99 per month for the 2.5mg strength, and your first 2.5mg pen costs £129.99 with code FIRST40. All six strengths are in stock, and the price shown is the price paid.

If Wegovy is the better fit, the Wegovy pen first order starts from £99.99 for the first pen. Prices were checked 10 October 2026.

03 · Honest limits

What the evidence cannot tell you

Trial results report group averages and the share of people passing weight-loss thresholds, not which characteristics make a person respond better to one medicine. Anyone claiming to know in advance, for example from a blood test or a social media post, is going beyond the evidence. Both are effective, results vary, and a prescriber reviews your response over time.

If you want to understand non-response in general, our guide on why some people do not respond to GLP-1 treatment covers the common reasons without overstating what is known.

04 · What the trials show

What the head-to-head trial actually shows

SURMOUNT-5 is the first large head-to-head trial of tirzepatide against semaglutide 2.4mg for weight management. It enrolled 751 adults who took either medicine for 72 weeks. Tirzepatide users lost 20.2% of body weight on average, versus 13.7% on semaglutide 2.4mg (Wegovy).¹⁵ In kilograms, the average loss was 22.8 kg on tirzepatide and 15.0 kg on semaglutide.

Those averages answer a population question: which medicine gave more weight loss across the group? They do not answer your question, which is whether you personally will do better on one. To see why, look at the threshold figures. At least 10% of body weight was lost by 81.6% on tirzepatide and 60.5% on semaglutide. At least 15% was lost by 64.6% versus 40.1%. At least 20% by 48.4% versus 27.3%, and at least 25% by 31.6% versus 16.1%.¹⁵

Read these the other way round. Since 81.6% of people on tirzepatide reached at least 10%, some did not. And on semaglutide, 27.3% lost at least 20% and 16.1% lost at least 25%, which is a very large response. The two groups overlap heavily. A person on semaglutide can outperform a person on tirzepatide, even though the tirzepatide average is higher.

Only SURMOUNT-5 supports a direct comparison of the two medicines. Other trials used different populations, different durations and different designs, so their numbers should never be set side by side as though they were head to head. For example, 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.⁹ That tells you semaglutide works against placebo, not how it ranks against tirzepatide.

STEP 1 also reports the spread: 86.4% of adults on semaglutide 2.4mg lost at least 5% of body weight, 69.1% lost at least 10% and 50.5% lost at least 15%, compared with 31.5%, 12.0% and 4.9% on placebo.⁹ Again, these are trial averages and proportions, and individual results vary.

The takeaway is not that semaglutide is the better medicine. It is that the higher tirzepatide average is real, the overlap between groups is also real, and neither fact settles what will happen for you. If you want the broader comparison, the page on whether semaglutide works better than tirzepatide approaches it from the other direction.

One further point on reading headline figures: they are measured at a fixed time point, 72 weeks in SURMOUNT-5. A person who loses more slowly early on may still arrive at a similar place, and a person who loses quickly may plateau. Judging a medicine on a few weeks of data is the most common way to misread it.

05 · Why responses differ

Why two people on the same medicine get different results

First, the medicines work differently. Tirzepatide activates two natural gut-hormone receptors at once, GIP and GLP-1. Together these help regulate appetite, slow how quickly the stomach empties and improve how the body responds to insulin. Semaglutide is a single-action GLP-1 medicine.¹ The dual action is what distinguishes tirzepatide from single-action GLP-1 medicines such as semaglutide. It does not mean every individual will respond more to the dual action.

Second, dose matters. In SURMOUNT-1, people taking tirzepatide alongside diet and exercise lost on average 15% of body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² Someone who stays on a lower strength because of side effects is not getting the same exposure as someone who reaches 15mg. The same logic applies to semaglutide, where the licensed maintenance dose is 2.4mg, reached from week 17 on the standard ladder.

Third, treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them. Two people on the same pen with different eating patterns and activity levels will see different results. That is not a failure of the medicine.

Fourth, consistency. Missed doses, long gaps and stopping early all change the outcome. People who cannot tolerate one medicine may stop it, and the averages then reflect that.

Fifth, pace. Weight loss is gradual by design, and early weeks are an adjustment phase. Someone who judges the medicine at four weeks will draw a different conclusion from someone who judges it at 16 or 72.

It is also worth remembering that comparing your result with another person's is rarely informative; different starting weights, doses and timescales make the comparison unreliable.

SURMOUNT-5 itself showed this overlap. Tirzepatide had the higher average and more people crossing every threshold, yet a sizeable share of people on semaglutide did very well.¹⁵ That is the honest answer to your question in one sentence: yes, individuals vary, and no, we cannot tell you beforehand which way you will fall.

If your first medicine has not worked as you hoped, the question to ask is not only whether the other medicine is better but whether the first was given a fair trial at an effective dose. Our guide to whether Wegovy works better than Mounjaro for some people takes a similar view of the brand-name comparison.

06 · Tolerance and side effects

Tolerance: will one make me less sick than the other?

In STEP 1, gastrointestinal side effects were reported by 74.2% of people on semaglutide 2.4mg, compared with 47.9% on placebo. And 7.0% stopped treatment because of side effects, compared with 3.1% on placebo.⁹ Different trials are not a fair comparison, so these figures should not be set against another trial's tirzepatide figures.

For the early weeks on tirzepatide, mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle. Experiences differ widely: some people notice appetite change and early loss in week one, others feel little until a higher dose, and both are normal.¹³

Why might someone tolerate one medicine better? If you have had a rough time on one medicine, that is a genuine reason to discuss the other with a prescriber. It is also a reason to discuss whether a slower step-up or staying longer on a lower strength is appropriate, which only a prescriber can decide.

Do not make changes on your own. The leaflet for your medicine lists the side effects to watch for and when to seek help. If you experience a new symptom, discuss it with your prescriber. You can also report any suspected side effect through the MHRA Yellow Card scheme.¹⁹

If you notice a mood change of any kind, mention it to your prescriber.

Tolerance is individual, so review your own experience over several weeks with a clinician. Some people find the first medicine they try suits them; others change. Changing is a normal part of treatment, not a sign that something has gone wrong.

Eating smaller portions and paying attention to how full you feel are sensible habits on either medicine.

07 · Why a prescriber may choose semaglutide

Why a doctor might prescribe semaglutide instead of tirzepatide

A prescriber may choose semaglutide for reasons that have nothing to do with which has the higher average, because the right medicine depends on your health profile, tolerance and the prescriber's clinical judgement. SURMOUNT-5 itself states that both are effective, licensed treatments and that the choice should not rest on the headline number alone.¹⁵

• Previous experience. If you have already been on semaglutide and responded well and tolerated it, there may be little reason to change.
• Tolerance. If another medicine caused problems for you, your prescriber may prefer the alternative.
• Your health history. Suitability checks look at your whole medical picture, and the answer can differ between people.
• Preference and availability. Some people simply prefer one product, and availability at the time of order can matter. Check availability when you order.

Licensing is a separate point. 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 a comparison of Mounjaro with Ozempic for weight loss is really a comparison of Mounjaro with Wegovy, and a regulated UK pharmacy will not supply Ozempic for weight loss.¹⁸ If you have seen advice about Ozempic, our page on whether Ozempic works better than Mounjaro for some people explains that licensing point in more depth.

The Wegovy dose ladder runs 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg once weekly. Titration steps up after at least 4 weeks and reaches the 2.4mg maintenance dose from week 17.¹⁸ The 2.4mg dose is the licensed maintenance dose for weight management.

Tablets are now part of the picture too. There is no tablet form of Mounjaro, since tirzepatide is injection-only in the UK. Two GLP-1 weight-loss tablets are licensed: Wegovy tablets (oral semaglutide), approved by the MHRA in June 2026, and Foundayo (orforglipron), approved in August 2026. They are different medicines with their own dosing, eligibility checks and trial results, and both are prescription-only.²⁰²¹

What is not a good reason to choose a medicine is a search for something cheaper that skips clinical oversight. The phrase "poor man's Ozempic" is used online for supplements such as berberine. These 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 are not an alternative to a licensed treatment.

If you are unsure which suits you, the consultation exists for exactly this question. A prescriber reviews your answers rather than a scoring script, and unsuitable orders are refunded automatically.

08 · Switching and mixing

Switching between semaglutide and tirzepatide safely

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

Never run two GLP-1 medicines together. Mounjaro must not be combined with other GLP-1 medicines, with unlicensed "research" peptides such as retatrutide, which has no UK licence, or with compounded copies. These combinations have no safety data and no regulated supply chain. If something offers faster results outside a licensed pathway, that is the warning sign.⁷

This is also why we advise against trying to engineer a better response by stacking products. If one medicine has not worked as hoped, the answer is a prescriber conversation, not an extra product. Our page on retatrutide compared with tirzepatide explains why an unlicensed option is not a safe substitute.

If you take other medicines, tell your prescriber at consultation. Insulin and sulfonylureas, for example, may need dose adjustments because of the risk of low blood sugar. That does not mean they cannot be used alongside treatment, but a prescriber must plan it. Mounjaro can also reduce how well oral contraceptive pills are absorbed because it slows stomach emptying, so ask about this if it applies to you.⁷ The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹

What a switch looks like in practice

• You tell your prescriber why you want to change: tolerance, response, preference or availability.
• The prescriber reviews your history and your current dose.
• The earlier medicine is stopped and a washout interval is observed.
• The new medicine starts at a dose the prescriber judges appropriate, often the lowest.
• You are reviewed as the dose is stepped up.

Starting again at a low dose can feel like a step backwards if you had reached a high dose previously. It is a safety measure, and the early weeks are an adjustment phase. For a person moving to Mounjaro, a first order at any dose is £40 less with code FIRST40, and every later order is £25 off the standard price (code DOSE25). The dose chosen is always the prescriber's decision, not ours or yours.

Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹ If you are coming off Mounjaro in order to try Wegovy, your prescriber will take that into account.

If you are curious about newer combinations in development, for instance the one discussed on our page about whether CagriSema is better than tirzepatide, remember that unlicensed or in-development products are not options to self-source. Regulated supply is the line to hold.

09 · If it isn't working

Why tirzepatide may seem not to work, and what to do

Tirzepatide can seem not to work because weight loss is gradual by design, and the first weeks on 2.5mg are an adjustment phase in which losses are usually modest. Most measurable progress builds from 5mg onward, month by month. Trials measured results at 72 weeks, so think in months, not days, and judge progress by trend rather than individual weigh-ins.

A sensible three-month expectation on a standard titration is mid single digits as a percentage of body weight, with wide individual variation. In SURMOUNT-1, average weight loss built month by month, with the full 15–21% averages measured at 72 weeks, not at 12.² Slower early progress does not predict failure, because the dose you respond to may still be ahead of you.

The formal review point

Treatment response is reviewed by your prescriber. 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.¹¹ That conversation is the proper moment to ask whether semaglutide would suit you better.

Plateaus

Plateaus of a few weeks are normal and expected as the body adapts to a lower weight. Within the licence, the responses are:

• Review food intake honestly, because portions drift back up.
• Protect protein and activity.
• Check the basics, such as sleep and alcohol.
• Discuss with your prescriber whether a dose step-up is appropriate if you are not yet at maximum.

A plateau is not a reason to double doses or add unlicensed products.

What about muscle?

Protect protein and activity, whichever medicine you take.

Beyond the scales

Weight is not the only outcome. In trials, weight loss on tirzepatide came with average improvements in waist size, blood pressure, cholesterol and blood-sugar measures, and most participants with prediabetes returned to normal blood-sugar levels. These are trial-average secondary outcomes, and individual results vary.² They are why prescribers talk about weight management as health management.

So, if you feel tirzepatide is not working, check four things first: how long you have been on it, which dose you reached, how consistently you take it, and whether food and activity have drifted. Then have the review. Only after that is it reasonable to ask whether a different licensed option would suit you better. Switching too soon, before a dose has had time to work, may mean you never learn what the first medicine could have done.

10 · Slower or faster results

Does semaglutide work slower than tirzepatide?

What SURMOUNT-5 measured was the total result at 72 weeks: 20.2% on tirzepatide versus 13.7% on semaglutide 2.4mg.¹⁵ That is a difference in the amount lost over the full period, and it does not describe the month-by-month path.

Both medicines use stepped dose ladders, and early results are limited on either because you start low. Tirzepatide begins at 2.5mg and moves through 5mg, 7.5mg, 10mg, 12.5mg and 15mg. Wegovy begins at 0.25mg and steps up after at least 4 weeks, reaching the 2.4mg maintenance dose from week 17.¹⁸ In both cases, you spend the early weeks below the full dose.

Because of this, comparing your speed to somebody else's is rarely useful. The person who seems faster may be on a higher dose, may have a different starting weight, or may be losing water weight early. Early loss includes water weight, so the trend over weeks matters more than any single weigh-in.

What to expect over the first year

A realistic picture: modest early progress, steadier progress through the middle doses, and the full trial averages measured at 72 weeks, not before. SURMOUNT-1 reported 5mg, 10mg and 15mg averages of 15%, 19.5% and 20.9% at 72 weeks, with 85%, 89% and 91% of participants respectively losing at least 5% of body weight. Half of participants on 10mg and 57% on 15mg lost at least 20%.² These are tirzepatide-only trial averages, and individual results vary.

For semaglutide, the STEP 1 figures were measured at 68 weeks.⁹ The time points differ, which is another reason not to read across the trials.

Instead of asking which is faster, ask which you can follow consistently at an effective dose, and whether your reviews show a trend in the right direction. That is a practical test, and it is the one your prescriber will use.

One caution on speed: nothing here supports shortcuts. If progress feels slow, discuss it rather than adjusting your own dose.

11 · 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 If you are pregnant or planning to conceive, Mounjaro must not be used during pregnancy and should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly.

12 · Costs and NHS access

What switching or starting costs, and what about the NHS?

Cost can reasonably influence your choice, so here is how our prices work, using live figures. A Mounjaro pen is a four-week supply. The standard price of the 2.5mg pen is £169.99, and the 5mg pen is £218.99. At the other strengths, the standard prices are £279.99 for 7.5mg, £290.99 for 10mg, £319.99 for 12.5mg and £329.99 for 15mg. Those are per month, which works out at £42.50 per week at 2.5mg and £82.50 per week at 15mg.

A new customer gets £40 off their first order at any dose with code FIRST40, including people switching to us at a higher dose. Your first 2.5mg pen therefore costs £129.99, and switching at 15mg, your first order is £289.99. After that, every later order is £25 off the standard price (code DOSE25).

For planning, if you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £959.96 at standard prices. A first year of 13 pens costs £2,711.88 if you stay on 5mg after your 2.5mg starting pen, up to £3,599.88 if you step up through every dose to 15mg. These totals are before discounts: a new customer's first order is £40 less and every later order £25 less. For 7.5mg, 10mg or 12.5mg, use that dose's monthly price rather than a year figure.

Across the UK pharmacies we track, the cheapest and dearest Mounjaro pens across all doses run from £143.96 to £339.00, and the gap between providers for the same dose ranges from £27 to £41 (checked 10 October 2026). Comparing providers dose by dose is worthwhile.

If you are weighing Wegovy, your first pen is £99.99 on a first order. If you want to compare every option, our overview of all weight loss treatments sets them out.

NHS access

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 NHS primary-care rollout began in June 2025 with the highest-need groups first, initially BMI 40+ with four or more qualifying conditions.⁴⁶ Full rollout is expected to take years, which is why 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 receive NHS prescriptions, the England charge is £9.90 per item, though the rules for these medicines depend on the service.

Private treatment through us involves a free consultation, review by a GPhC-registered prescriber, same-day dispatch when ordered by 3pm, and free next-day tracked delivery. If the prescriber decides treatment is not suitable, your order is refunded automatically in full. Official LillyDirect supply means genuine KwikPens straight from Eli Lilly's UK distribution. We also offer Klarna and pay-monthly options with no subscription lock-in. Repeat orders re-check suitability, with no auto-shipping.