Saxenda vs Mounjaro vs Wegovy: UK Comparison (October 2026)

01 · The short answer

Saxenda vs Mounjaro vs Wegovy: which suits whom?

There is no single winner for everyone, because the right medicine depends on your health history, how you tolerate side effects and what a prescriber judges appropriate.

Saxenda (liraglutide) suits someone whose prescriber recommends a daily injection. It is a daily injection, unlike the two weekly medicines. Wegovy (semaglutide 2.4mg) is a weekly injection with a four-step titration to its 2.4mg maintenance dose. Mounjaro (tirzepatide) is also weekly, but it acts on two gut-hormone receptors rather than one.¹

If you want a direct, trial-based comparison, only Mounjaro versus Wegovy has one. Our guides on Wegovy versus Mounjaro and Saxenda against Mounjaro go deeper on each pairing.

02 · Side by side

Key differences at a glance

Different trials enrol different people, run for different lengths and are not comparable with each other. Only SURMOUNT-5 supports a direct comparison.

03 · Deciding

Decision factors to discuss with a prescriber

The first factor is injection frequency. A daily injection suits some people's routines and a weekly one suits others. Weekly treatments mean 52 injections a year instead of about 365.

The second is tolerance. Side effects are most likely when you start or step up a dose, and for most people they ease within days to a few weeks as the body adjusts. Your prescriber will ask about your medical history, other medicines and any conditions such as type 2 diabetes.

The third is the evidence. Mounjaro and Wegovy have been compared directly in one large trial; Saxenda has its own separate trial. Both Mounjaro and Wegovy are effective, licensed treatments, and your health profile matters more than a headline number.¹⁵

04 · Cost

What do they cost?

Compare first orders with first orders. Your first 2.5mg Mounjaro pen is £129.99 as a first-order price, and your first Wegovy pen is £99.99 as a first-order price. Both are starting-dose pens, and both step up in strength over time.

Standard prices apply to repeat orders: the 2.5mg Mounjaro pen is £169.99 per month at the standard price. Across the UK pharmacies we track, Mounjaro pens ranged from £143.96 to £319.99 per month at all doses (checked 24 October 2026). For a deeper look at cost across the three medicines, see our cost comparison and our monthly cost for Saxenda and Mounjaro. Saxenda needs a daily supply, so ask your pharmacy for its current price when you compare.

05 · Saxenda: the SCALE trial

Saxenda (liraglutide): what the SCALE trial found

In the SCALE trial, adults taking liraglutide 3.0mg (Saxenda) for 56 weeks lost on average 8.0% of body weight (8.4 kg), compared with 2.6% (2.8 kg) on placebo. Of those on liraglutide, 64% lost at least 5% of body weight (versus 27% on placebo), and 33% lost more than 10% (versus 10%).

These are trial averages, and individual results vary. Treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.

Saxenda is supplied at 6mg per millilitre and is a daily injection, unlike the weekly pens. That daily schedule is the practical difference most people notice first.

If you are on Saxenda and not losing weight, speak to your prescriber rather than changing anything yourself. They can review your dose, your diet and activity plan and whether another licensed treatment suits you. Our Saxenda and Mounjaro price guide covers the cost side of that decision.

06 · Wegovy: the STEP 1 trial

Wegovy (semaglutide 2.4mg): what STEP 1 found

In STEP 1, adults on semaglutide 2.4mg (Wegovy) lost on average 14.9% of body weight over 68 weeks, compared with 2.4% on placebo.⁹ Some 86.4% lost at least 5% of body weight (versus 31.5% on placebo), 69.1% lost at least 10% (versus 12.0%), and 50.5% lost at least 15% (versus 4.9%).⁹

Wegovy pens come as 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg once weekly. The dose steps up after at least 4 weeks and reaches the 2.4mg maintenance dose from week 17, which is the licensed maintenance dose for weight management.¹⁸

The same trial reported tolerability figures. 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

You can read more in our Wegovy and Mounjaro weight-loss guide.

07 · Mounjaro: SURMOUNT trials

Mounjaro (tirzepatide): SURMOUNT-1 and SURMOUNT-5

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. Most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.¹ This dual action is what distinguishes it from single-action GLP-1 medicines such as semaglutide.

In the SURMOUNT-1 trial of 2,539 adults, 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. The comparison group, on lifestyle changes alone, lost 3.1%.² At 72 weeks, 85% on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of body weight. Half of those on 10mg and 57% on 15mg lost at least 20%.²

For a worked example only: for someone starting at 100 kg, 20.9% is about 21 kg. Trial averages do not predict your own result, and individual results vary.

You can browse all six strengths on the Mounjaro pen page, where every dose is in stock.

08 · The head-to-head: SURMOUNT-5

Mounjaro vs Wegovy: the SURMOUNT-5 head-to-head

SURMOUNT-5 is the first large head-to-head trial of tirzepatide and semaglutide for weight loss. In it, 751 adults took tirzepatide or semaglutide 2.4mg for 72 weeks. Average loss was 20.2% of body weight on tirzepatide versus 13.7% on semaglutide 2.4mg (Wegovy). In kilograms, that was 22.8 kg versus 15.0 kg.¹⁵

The share of people reaching each loss threshold was also reported:

• At least 10% of body weight: 81.6% on tirzepatide vs 60.5% on semaglutide.
• At least 15%: 64.6% vs 40.1%.
• At least 20%: 48.4% vs 27.3%.
• At least 25%: 31.6% vs 16.1%.

Both are effective, licensed treatments. Which suits you depends on your health profile, tolerance and your prescriber's advice, not the headline number alone.¹⁵ Saxenda was not part of this trial. Our page on Wegovy strength versus Mounjaro covers the dose side.

09 · Side effects and safety

Side effects: what to expect and when to seek help

Digestive side effects are the most common with Mounjaro. The most common effects, affecting more than 1 in 10 people, are nausea, diarrhoea, vomiting, constipation and abdominal discomfort. Common effects (up to 1 in 10) include indigestion, reduced appetite, dizziness, reflux, burping, hair shedding and injection-site reactions. They are most likely when starting or moving up a dose, and for most people they ease within days to a few weeks.¹³

For Wegovy, STEP 1 recorded gastrointestinal effects in 74.2% of people on semaglutide 2.4mg versus 47.9% on placebo.⁹ For Saxenda's side effects, read the patient information leaflet supplied with it and ask your prescriber or pharmacist.

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 the skin or eyes (possible gallbladder problems);
• 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.¹³ You can report any suspected side effect through the Yellow Card scheme.¹⁹

If you use the contraceptive pill, Mounjaro slows stomach emptying and can reduce how well it is absorbed. The advice is to 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. Implants, coils and injections are unaffected.⁷

10 · Switching and combining

Switching between them, and why you never combine them

You should never run two GLP-1 medicines together. Mounjaro must not be combined with other GLP-1 medicines, unlicensed research peptides (such as retatrutide, which has no UK licence) or compounded copies. These combinations have no safety data and no regulated supply chain.¹

There is also no licensed direct conversion between semaglutide and tirzepatide. A switch 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. That is often the 2.5mg starting dose, sometimes adjusted based on your history.¹

Ozempic is sometimes mixed into these comparisons. It is semaglutide licensed for type 2 diabetes, not a UK weight-loss medicine. The licensed weight-management injections are Mounjaro and Wegovy, with Saxenda another licensed injectable. A regulated UK pharmacy will not supply Ozempic for weight loss.

11 · NHS access and tablets

NHS access, tablets and other options

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. The NHS primary-care rollout began in June 2025 with the highest-need groups first, initially BMI 40+ with four or more qualifying conditions.⁴ Full rollout is expected to take years, so many people who meet the licensed criteria choose regulated private treatment. NHS access to Wegovy runs through specialist weight-management services; ask your GP.

There is no tablet form of Mounjaro; tirzepatide is injection-only in the UK. Two GLP-1 weight-loss tablets are now 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 and eligibility checks. Orlistat is a tablet that blocks some dietary fat absorption and produces smaller average losses; see orlistat versus Wegovy and Mounjaro. Berberine and similar "natural GLP-1" supplements are not medicines and have no comparable trial evidence.

12 · Storage and getting started

Storing Mounjaro and how ordering works

Keep Mounjaro pens in a fridge at 2–8°C and never freeze them. Once in use, a pen can be kept out of the fridge not above 30°C for up to 30 days, then discarded. Keep the cap on to protect it from light, and never use a pen that has been frozen.¹³

Ordering from us takes three steps. First, complete a short, free online consultation with no obligation. Second, a GPhC-registered prescriber reviews it. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full. Third, our registered pharmacy dispenses it, with same-day dispatch when ordered by 3pm and free next-day tracked delivery in temperature-controlled packaging. We are GPhC registered (9012878), and our Mounjaro comes from official LillyDirect supply.

Ready to start? Start your free consultation, or see all weight loss treatments. Mounjaro is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. It is used alongside a reduced-calorie diet and increased physical activity. Individual results vary, and this page is information, not a substitute for medical advice.