Mounjaro vs Saxenda: Which is right for you?

If you have been confused about choosing between Mounjaro and Saxenda for a while, that is completely normal.

Mounjaro and Saxenda are prescription weight loss medicines with real results and real side effects, and the honest truth is that the two are different enough that the comparison takes a bit of unpicking.

This article is not a recommendation.

Whether either treatment is suitable for you is decided by a GMC-registered prescriber after they have read your medical history.

What we can do here is lay out the evidence clearly so the conversation is easier when you get to it.

If you’re confused between Wegovy and Saxenda, our Wegovy vs Saxenda guide can be pretty helpful too.

Before you begin: A little bit about OnlineClinic

OnlineClinic has been operating since 2011 and has treated more than 2.1 million patients.

The pharmacy is registered with the General Pharmaceutical Council (GPhC), our prescribers are registered with the General Medical Council (GMC), and the service is regulated by the Care Quality Commission (CQC).

As of August 2026, on Trustpilot, the service rating is 4.6 out of 5 based on 6,703 reviews.

Three things have shifted recently with regards to Saxenda and Mounjaro, and these might change the direction of your decision entirely.

• Liraglutide came off patent, and generic versions have started arriving in the UK. At least four companies are expected to hold UK marketing authorisations covering obesity, diabetes, or both. This is the first time generic versions of any GLP-1 medicine have been able to reach the UK market, and one generic (marketed as Nevolat) launched in May 2026.
• Victoza, the lower-dose liraglutide product licensed for type 2 diabetes, has been discontinued. It has been unavailable in the UK since August 2023, and Novo Nordisk is winding down its European marketing. Saxenda, the higher-dose product licensed for weight management, remains licensed, but supply has been constrained.
• The gap at the top of the market has widened, not narrowed. Tirzepatide and semaglutide have both moved on since Saxenda's licence. Wegovy now goes up to 7.2mg in the UK, which puts two weekly medicines a long way ahead of daily liraglutide with regards to average weight loss.

None of that makes Saxenda a less ideal weight loss medicine.

It does mean the reasons for choosing it in 2026 are more specific than they used to be.

Both medicines mimic hormones your gut already makes after you eat.

Those hormones tell your brain you have had enough and slow how quickly your stomach empties.

When Mounjaro or Saxenda enters your body, you feel full sooner, you stay full for longer, and food stops occupying quite so much mental space. Plenty of patients describe the change as the background noise going quiet.

The difference between the two lies in how many hormones they mimic, and for how long.

• Saxenda mimics one hormone, GLP-1. Liraglutide stays in the body for about 13 hours, which is why it is injected daily.
• Mounjaro mimics two hormones, GLP-1 and GIP. Tirzepatide lasts in the body long enough for one injection a week, and the second hormone helps with higher average weight loss.

Here are the numbers, and the caveat that goes with them.

Mounjaro in the SURMOUNT-1 trial

The SURMOUNT-1 trial followed 2,539 adults with obesity for 72 weeks, comparing three tirzepatide doses against a placebo, with lifestyle support for everyone.

Average weight loss at 72 weeks:

• 5mg: 15.0%
• 10mg: 19.5%
• 15mg: 20.9%
• Placebo: 3.1%

Around 86% of people on the highest dose lost at least 5% of their starting weight.

Saxenda in the SCALE trial

The SCALE Obesity and Prediabetes trial followed 3,731 adults for 56 weeks at the 3mg daily dose.

Average weight loss at 56 weeks:

• Liraglutide 3mg: Roughly 8%
• Placebo: Roughly 2.6%

Why is there no head-to-head clinical trial for Mounjaro and Saxenda

There has never been a direct Mounjaro versus Saxenda trial, so anyone claiming a precise winning margin is filling in a gap that does not exist in the data.

What we do have is network meta-analysis, a statistical method for comparing treatments across separate trials.

A 2026 Bayesian network meta-analysis compared tirzepatide, semaglutide, and liraglutide in adults without type 2 diabetes.

Every tirzepatide 15mg dose came out statistically ahead of liraglutide 3mg on weight reduction.

An earlier network analysis of more than 12,300 patients reached the same conclusion.

This is the part patients underestimate, and it cuts both ways.

52 injections a year (Mounjaro) against 365 injections a year (Saxenda) . For most people, that is the deciding practical factor, and it is why weekly treatments have taken over. One appointment with yourself on a Sunday evening is easier to keep than a daily habit.

But a daily dose is easier to steer. If a weekly injection disagrees with you on Tuesday, you are living with it until the following Monday. With a daily medicine, your prescriber can hold you at a dose, step you back down, or slow the climb, and you feel the effect of that change within a day or two.

That responsiveness is the honest case for Saxenda, and it is a genuine one for people who have had a rough time with a weekly treatment.

Both medicines start on a low dose and then the doses are dailled up gradually, for the same reason: Your stomach needs time to adjust to the medicine, and going too fast is what makes people feel awful.

Nobody has to reach the 15mg dose.

Many people settle at 5mg or 10mg because that is where the balance of results and side effects lands for them.

Our Mounjaro dosage schedule explained walks through each step.

One practical consequence of the different schedules: Saxenda tells you fairly quickly whether it suits you, because you reach the full dose inside five weeks.

Mounjaro takes longer to show what it can do, which is worth knowing if you are the kind of person who checks the scales daily.

We cover that expectation-setting in how long until Mounjaro starts working.

Because both medicines have the same mechanism of action, their side effects are also teh same.

Gastrointestinal side effects are most common, and they are worst with every dose increase.

Common for both, affecting more than 1 in 10 people:

• Nausea, usually heaviest in the first few weeks
• Diarrhoea
• Constipation
• Vomiting, less common but real
• Reduced appetite, which is partly the point, but it can feel odd at first
• Tiredness
• Headache

Get medical help the same day

Both medicines carry rare but serious risks. Contact a prescriber or seek urgent medical advice if you have:

• Severe stomach pain that does not settle, which can indicate pancreatitis
• Pain under the right ribs, fever, or yellowing of the skin or eyes, which can indicate gallbladder problems
• Signs of low blood sugar, particularly if you also take insulin or a sulphonylurea
• Swelling of the face, lips, or throat, or difficulty breathing, which needs immediate attention

On tolerability, the above-mentioned network meta-analyses point in a consistent direction: Liraglutide was associated with a higher rate of stopping treatment because of side effects than tirzepatide. That is partly the daily exposure and partly the faster climb to full dose.

Our Mounjaro side effects week by week guide covers the timeline in detail, and most of the practical advice in it (smaller meals, less fat early on, plenty of fluids) applies to Saxenda too.

This is a real difference between the two, and it surprises people.

Saxenda's licence contains a formal stopping rule.

If you have not lost at least 5% of your starting body weight after 12 weeks on the full 3mg daily dose, treatment should be stopped and reassessed, because continuing is unlikely to give you enough benefit to justify it.

Mounjaro's UK licence does not carry an equivalent fixed rule, although your prescriber will still review how you are getting on and will not keep you on something that is not working.

There is a reasonable way to read this.

Saxenda has a built-in checkpoint that stops people from spending money on a medicine that is not doing anything for them. Some patients find that reassuring.

Liraglutide's product information asks prescribers and patients to keep an eye on mood and behaviour during treatment, and it is not generally recommended for people with a history of depression or thoughts of self-harm.

If any of that applies to you, tell the prescriber during your consultation.

It does not automatically rule out treatment, but it changes which medicine makes sense and how closely you are monitored.

And if your mood shifts noticeably once you have started the treatment, contact your prescriber or GP rather than to wait it out.

Both are biological medicines, so both need to be refrigerated at 2°C to 8°C, and neither can be used if it is frozen.

• Saxenda pens last for 30 months unopened if refrigerated. Once you have taken the first dose, the pen must be used within 30 days and can be kept below 30°C during that time.
• Mounjaro pens are multi-dose. Once opened, they can be kept at room temperature of upto 30°C for upto 30 days in its original packaging.

No single answer covers everyone. The decision usually falls out along these lines.

The prescriber's judgement is the part that actually matters here.

They see your full medical history, your current medications, your BMI, and any other conditions, and they can explain why one fits your situation better than the other.

Neither Mounjaro nor Saxenda is suitable if you:

• Are pregnant, planning a pregnancy, or breastfeeding
• Have had a serious allergic reaction to either active ingredient

Tell your prescriber, and expect a longer conversation, if you have:

• A history of pancreatitis or gallbladder disease
• Severe kidney or liver problems
• Diabetic retinopathy
• A history of an eating disorder
• Other diabetes medication, especially insulin or sulphonylureas
• A history of depression or thoughts of self-harm, which is particularly relevant to liraglutide
• Oral contraception, since GLP-1 medicines can affect how it is absorbed. Our guide on Mounjaro and contraception goes into detail about how contraceptio affects GLP-1 medicines.

To be eligible for treatment, you also need to be aged 18 or over with:

• A BMI of 30 or above, or
• A BMI of 27 or above alongside a weight-related condition such as type 2 diabetes, high blood pressure, sleep apnoea, fatty liver disease, PCOS, osteoarthritis, or heart disease

If neither applies, this class of medicine is not the right treatment, and our prescribers will say so and explain what else might help.

Switching in either direction is common and manageable, but it is a prescriber-led decision rather than something to do on your own.

Going from Saxenda to Mounjaro. Liraglutide clears quickly from the body, within a few days, so no long gap is usually needed during the switch. You would normally start Mounjaro at the 2.5mg starter dose regardless of the Saxenda dose you were on, and increase the dose from there.

Going from Mounjaro to Saxenda. Less common, but it happens when someone cannot tolerate weekly dosing or wants finer control. You would restart the liraglutide from the 0.6mg dose rather than jumping to the 3mg dose.

Either way, expect the early side effects to reappear briefly while your body adjusts to the new medicine. That is normal and not a sign the switch has failed.

If you are switching because your weight loss has stopped rather than because of side effects, read our guide on Mounjaro weight loss plateau first. A plateau does not always mean the medicine has stopped working.

At OnlineClinic, the prices for Mounjaro starts at £139.99 for the 2.5mg starter injection pen.

We do not prescribe Saxenda at OnlineClinic.

Every price includes the prescription, the consultation, the packaging, the needles, a sharps bin, and next-day delivery.

There are no hidden fees, and no charge at all if the prescriber decides the treatment is not suitable for you.

Our process is straightforward. From start to finish, this is what happens when you order with us:

1. Fill in the medical questionnaire. It takes 5 to 10 minutes. The questions are thorough on purpose.
2. A GMC-registered prescriber reviews your answers. If they need more details or want confirmation from the clinician managing your heart, they will message you through your account.
3. If treatment is approved, it is dispensed and dispatched. Next-day delivery, with needles, a sharps bin, and the full patient information leaflet included.
4. If it is not approved, the prescriber explains why. You are not charged for treatment that is not issued.

Our Mounjaro prices start at £139.99, and every price includes the prescription, the consultation, the packaging, and delivery. There are no hidden fees.

We do not prescribe Saxenda at OnlineClinic. We prescribe Mounjaro for weight management following an online consultation.