Semaglutide vs tirzepatide — 7 proven differences.
Semaglutide vs tirzepatide is the comparison most people face when choosing a weight loss medicine in the UK. Both are weekly injections with strong results, but they work differently, cost different amounts and suit different people.
This guide compares semaglutide vs tirzepatide using the head-to-head SURMOUNT-5 trial, covering how each works, weight loss, side effects, doses, UK prices, heart benefits, diabetes and who each may suit.
See doses, pricing and support for licensed tirzepatide and semaglutide.
Explore Mounjaro → Explore Wegovy →Semaglutide vs tirzepatide: quick comparison
This table sums up the semaglutide vs tirzepatide comparison. The detail behind each row follows below.
| Feature | Semaglutide | Tirzepatide |
|---|---|---|
| UK brands | Wegovy, Ozempic, Rybelsus, Wegovy pill | Mounjaro |
| Hormones targeted | GLP-1 | GLP-1 + GIP |
| Head-to-head weight loss (SURMOUNT-5, 72 weeks) | 13.7% | 20.2% |
| Forms | Weekly injection or daily tablet | Weekly injection |
| Top weight loss dose | 2.4mg (7.2mg higher dose approved) | 15mg |
| Proven heart benefit | Yes (SELECT trial) | Outcome trials reporting |
| Manufacturer | Novo Nordisk | Eli Lilly |
In short, semaglutide vs tirzepatide usually comes down to more weight loss with tirzepatide versus more choice of forms, a longer track record and proven heart benefits with semaglutide.
How each medicine works
To understand semaglutide vs tirzepatide, start with the hormones. Semaglutide copies GLP-1, a gut hormone that signals fullness, slows stomach emptying and helps control blood sugar. It works through a single hormone pathway.
Tirzepatide activates GLP-1 and a second hormone receptor, GIP. GIP appears to add to the appetite and blood sugar effects, and may help the body handle fat differently.
The simplest way to see semaglutide vs tirzepatide: one hormone pathway versus two. That extra pathway is the main reason tirzepatide usually leads to more weight loss.
7 proven differences
1. Number of hormone targets
In semaglutide vs tirzepatide, this is the root difference: semaglutide targets GLP-1 only; tirzepatide targets GLP-1 and GIP.
2. Average weight loss
Tirzepatide produced 20.2% weight loss versus 13.7% for semaglutide in SURMOUNT-5.
3. Forms available
Semaglutide comes as injections and tablets; tirzepatide is injection only.
4. Dose schedules
Wegovy rises from 0.25mg to 2.4mg; Mounjaro rises from 2.5mg to 15mg.
5. Side effect tolerability
Both cause stomach side effects, but fewer people stopped tirzepatide for these reasons in SURMOUNT-5.
6. Heart evidence
Semaglutide has proven cardiovascular benefits from the SELECT trial; tirzepatide’s outcome data is still emerging.
7. UK price
Since September 2025, semaglutide is often cheaper than tirzepatide in the UK.
Head-to-head weight loss results
The clearest semaglutide vs tirzepatide evidence comes from SURMOUNT-5, a 72-week trial in 751 adults with obesity but without diabetes. People took the highest dose they could tolerate of each medicine.
| Result at 72 weeks | Semaglutide (1.7mg–2.4mg) | Tirzepatide (10mg–15mg) |
|---|---|---|
| Average weight loss | 13.7% | 20.2% |
| Average weight lost | 15.0kg | 22.8kg |
| Waist reduction | 13.0cm | 18.4cm |
| Stopped due to stomach side effects | 5.6% | 2.7% |
These results come from the SURMOUNT-5 trial summary (American College of Cardiology). They show a clear average advantage for tirzepatide, though many people do very well on semaglutide too.
Side effects compared
On side effects, semaglutide vs tirzepatide is closer than many expect. Both medicines share the same common side effects: nausea, diarrhoea, constipation, vomiting and indigestion. These are usually strongest when starting or increasing the dose and ease over time.
In SURMOUNT-5, fewer people stopped tirzepatide because of stomach side effects. Individual experience varies, and some people tolerate semaglutide better than tirzepatide.
Neither medicine is suitable during pregnancy or breastfeeding, or for people with a personal or family history of medullary thyroid cancer or MEN2. Seek urgent help for severe, persistent stomach pain. Tirzepatide can reduce how well the oral contraceptive pill works.
See our Wegovy side effects and Mounjaro side effects guides.
Dose schedules
| Weeks | Wegovy (semaglutide) | Mounjaro (tirzepatide) |
|---|---|---|
| 1–4 | 0.25mg | 2.5mg |
| 5–8 | 0.5mg | 5mg |
| 9–12 | 1mg | 7.5mg (if needed) |
| 13–16 | 1.7mg | 10mg (if needed) |
| 17+ | 2.4mg | 12.5mg–15mg (if needed) |
Both start low and rise every four weeks. See our Wegovy dosing schedule and tirzepatide dosage chart for full detail.
UK prices compared
Cost has become a bigger part of semaglutide vs tirzepatide in the UK. Since Eli Lilly raised Mounjaro’s UK list price in September 2025, semaglutide has often been the cheaper option. Typical UK private prices are about £186–£305 a month for Wegovy 2.4mg and about £130–£340 for Mounjaro depending on dose.
Compare the details in our semaglutide price and tirzepatide price guides. Value depends on results as well as cost.
Heart and health benefits
Heart evidence is one area where semaglutide vs tirzepatide favours semaglutide, for now. Semaglutide has the strongest heart evidence. In the SELECT trial, Wegovy cut heart attacks, strokes and cardiovascular deaths by about 20% in adults with heart disease and excess weight.
Tirzepatide has shown strong improvements in blood pressure, cholesterol and blood sugar, with cardiovascular outcome trials reporting. See our guide to GLP-1 and heart health.
Type 2 diabetes
For diabetes, semaglutide vs tirzepatide is a choice between two licensed options. Both medicines are licensed for type 2 diabetes: semaglutide as Ozempic and Rybelsus, tirzepatide as Mounjaro. In head-to-head diabetes trials, tirzepatide lowered HbA1c and weight more than semaglutide 1mg.
People using insulin or sulfonylureas may need dose changes to avoid low blood sugar. See our Mounjaro for type 2 diabetes guide.
Which may suit you?
Tirzepatide may suit you better if you:
- Want the largest average weight loss from a licensed medicine
- Have not reached your goals on semaglutide
- Have type 2 diabetes and want strong blood sugar and weight results
- Are comfortable with a weekly injection
Semaglutide may suit you better if you:
- Have heart disease and want proven cardiovascular benefits
- Prefer a daily tablet to an injection
- Want a lower monthly cost in the UK
- Tolerate it well and are losing weight steadily
Switching between them
Switching is common in semaglutide vs tirzepatide decisions. Many people move from semaglutide to tirzepatide when weight loss stalls, and some switch the other way for cost or side effect reasons. A prescriber should always guide the switch and choose the new starting dose.
Never take both at the same time. Our Wegovy vs Mounjaro and Mounjaro vs Ozempic guides cover brand-specific comparisons.
Brands and forms
Brand choice is another semaglutide vs tirzepatide difference. Semaglutide comes as Wegovy (weekly injection or daily tablet) for weight management and Ozempic or Rybelsus for diabetes. Tirzepatide comes as Mounjaro in the UK and Europe, and as Zepbound in the US.
Our semaglutide UK and tirzepatide UK guides explain each brand, and our Wegovy vs Zepbound guide covers the US comparison.
Semaglutide vs tirzepatide for different goals
The right answer to semaglutide vs tirzepatide often depends on what you want from treatment. For the largest possible weight loss, tirzepatide has the edge on average.
For people with heart disease, semaglutide’s proven cardiovascular benefit can matter more. For people who dislike injections, the semaglutide tablet is the only oral option.
Budget, side effects and how you responded to previous treatment all shape the semaglutide vs tirzepatide decision. A prescriber can help weigh these for your situation.
Appetite and food noise
Many people describe both medicines as turning down “food noise”, the constant background thoughts about eating. In semaglutide vs tirzepatide comparisons, users often report that tirzepatide feels stronger at higher doses.
Appetite effects are usually strongest in the first few days after each injection. Eating smaller, protein-rich meals helps on either medicine.
Real-world experience
Outside trials, semaglutide vs tirzepatide results vary widely. Some people lose more on semaglutide than average, while others find tirzepatide works far better for them.
In real-world semaglutide vs tirzepatide use, consistency matters as much as the medicine. Taking each dose on time, eating enough protein and staying active make a big difference to results.
Muscle and body composition
With any large weight loss, some of the weight lost is muscle as well as fat. This applies on both sides of semaglutide vs tirzepatide.
Eating enough protein and doing strength training two or three times a week helps protect muscle. Our GLP-1 and muscle loss guide has practical tips.
Stopping and weight regain
Both medicines work best long term. In the STEP-1 extension, people who stopped semaglutide regained about two-thirds of the weight they had lost within a year.
In SURMOUNT-4, people who switched from tirzepatide to placebo regained about 14% of their weight, while those who continued kept losing. On this point, semaglutide vs tirzepatide is the same: stopping usually means some regain.
When progress slows
Weight loss slows on both medicines after several months as your body adapts. On semaglutide, some people then switch to tirzepatide; see our Wegovy plateau guide.
On tirzepatide, reviewing dose, protein and activity usually helps; see what to do if Mounjaro stops working.
Day-to-day differences
Day to day, semaglutide vs tirzepatide feels similar: both injections are given once a week, on the same day, using a pen. In the UK, Wegovy FlexTouch pens and Mounjaro KwikPens each hold four weekly doses of one strength.
If you prefer tablets, only semaglutide offers that choice in the Wegovy pill. See our Wegovy pill vs pen guide.
Cost over a year
Looking at a full year gives a fairer semaglutide vs tirzepatide cost comparison. At average UK prices, a first year on Wegovy works out at roughly £2,450.
A first year on Mounjaro typically costs about £2,500 to £3,500, depending on which maintenance dose you reach. Staying on a lower dose that works keeps costs down on either medicine.
Alcohol on either medicine
Alcohol can worsen nausea and low blood sugar on both medicines, and adds calories that slow weight loss. In semaglutide vs tirzepatide terms, the advice is the same: keep it moderate and never drink on an empty stomach.
See our Wegovy and alcohol and Mounjaro and alcohol guides.
Who shouldn’t take either
Neither medicine is suitable during pregnancy or breastfeeding, or for people with a personal or family history of medullary thyroid cancer or MEN2. People with a history of pancreatitis or severe stomach conditions need careful assessment.
Whichever side of semaglutide vs tirzepatide you choose, a proper consultation is essential before starting.
Storage and travel
Both pens should be kept in the fridge between 2°C and 8°C before use and never frozen. Check each leaflet for how long a pen can be kept at room temperature.
When travelling, carry pens in hand luggage with a cool bag and your prescription. Our guide to storing GLP-1 medications covers both.
Getting the best results
Whichever way the semaglutide vs tirzepatide decision goes, lifestyle changes amplify results. Protein at every meal, plenty of water, regular walks and strength training all help.
Use the lower-appetite days after each injection to build lasting habits such as smaller portions and fewer snacks. Our best diet on Wegovy and best diet on Mounjaro guides have meal ideas for both sides of semaglutide vs tirzepatide.
Questions to ask your prescriber
- Which is more likely to help me reach my goal?
- Does my heart health make semaglutide a better fit?
- How will side effects compare for me?
- Which fits my budget over a year?
- If I have used one already, should I switch?
These questions help turn the general semaglutide vs tirzepatide comparison into a decision that fits you.
Key takeaways
- Semaglutide vs tirzepatide is one hormone pathway versus two
- In SURMOUNT-5, tirzepatide gave 20.2% weight loss versus 13.7% for semaglutide
- Fewer people stopped tirzepatide for stomach side effects in that trial
- Semaglutide has proven heart benefits and a tablet option
- Semaglutide is often cheaper in the UK since Mounjaro’s 2025 price rise
- Both lead to some weight regain if stopped
There is no universal winner in semaglutide vs tirzepatide. The best choice is the licensed medicine that suits your goals, health and budget, used alongside steady lifestyle changes.
Research and compounded versions
Some websites sell research semaglutide or tirzepatide, and compounded versions were common in the US during shortages. None of these are licensed medicines in the UK, and their dose and purity aren’t guaranteed.
For human use, choose licensed Wegovy, Ozempic or Mounjaro from a regulated pharmacy. Our research peptides UK legal guide explains why.
Beyond both: retatrutide
The semaglutide vs tirzepatide debate may soon have a third option. Retatrutide adds glucagon action to GLP-1 and GIP. In trials it produced even more weight loss than either, but it is not yet approved.
See our retatrutide vs tirzepatide and retatrutide vs semaglutide guides for the next step in the comparison.
Semaglutide vs tirzepatide isn’t about one drug being good and the other bad. Both are effective; the right choice depends on your goals, health and budget.
Mymetabolism TeamCommon questions — Semaglutide vs Tirzepatide
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