Liraglutide and Semaglutide: How They Compare and What the Evidence Shows

What the trial data actually shows when you put the two medicines side by side

The most instructive starting point is the evidence base. The STEP 1 trial enrolled 1,961 adults with obesity and followed them for 68 weeks; those taking semaglutide 2.4 mg lost around 15% of body weight on average, compared with roughly 2.4% in the placebo group. Liraglutide's pivotal SCALE Obesity and Prediabetes trial, run over 56 weeks, showed average losses closer to 8% at the 3 mg maintenance dose. Neither figure is a promise of what any individual will achieve, but the gap between them is consistent across multiple analyses and is one reason NICE, when it appraised semaglutide (Wegovy) for the NHS in Technology Appraisal TA875, considered it a clinically meaningful advance.

The mechanism behind the difference is partly pharmacological and partly practical. Semaglutide has a longer half-life, which is why one weekly injection maintains a steady level in the bloodstream. Liraglutide clears faster, requiring a daily injection and a more precise adherence routine. Missing a day of liraglutide has a more immediate impact on drug levels than missing a day of the weekly semaglutide schedule. That is not a trivial point: in real-world practice, adherence shapes outcomes as much as pharmacology does.

For a more detailed look at how the two medicines are structurally and clinically different, our page on how liraglutide differs from semaglutide goes deeper into the chemistry and half-life question.

Which is licensed for weight loss in the UK, and which is not available through nume

Both medicines hold UK licences for weight management, but the practical picture matters. Saxenda (liraglutide 3 mg) is licensed for weight management in the UK and is dispensed by some pharmacies. Wegovy (semaglutide 2.4 mg, and the newer 7.2 mg strength approved by the MHRA in January 2026) is licensed for the same indication. If you have ever wondered whether liraglutide is actually the same as semaglutide, the answer is no, and understanding that distinction also helps clarify why neither liraglutide nor Ozempic, which is also semaglutide but licensed specifically for type 2 diabetes, is the same product as Wegovy.

nume does not dispense liraglutide (Saxenda). The two weight-loss medicines available through our service are Wegovy (semaglutide) and Mounjaro (tirzepatide). If you have been researching liraglutide or semaglutide and want to understand your options, our weight-loss treatment overview sets out what is licensed, what the evidence says, and how the clinical assessment works.

A quick habit worth building: before ordering any prescription medicine online, take a minute to check the pharmacy on the GPhC register. A legitimate UK pharmacy will have a registered premises number you can verify in seconds. Ours is 9012878.

Side effects, safety signals and what to watch for on either medicine

The side-effect profiles of liraglutide and semaglutide overlap considerably because both act on GLP-1 receptors in the gut and brain. The most common complaints are gastrointestinal: nausea, loose stools, constipation and, for some people, reflux or burping. These effects tend to peak in the early weeks and settle once the body adjusts to treatment. Starting at a low dose and increasing gradually is the standard way to keep them manageable.

The NHS medicines page for semaglutide covers what to expect and when to seek help. The same principle applies to liraglutide. The signal that warrants urgent attention on either medicine is severe, persistent abdominal pain, particularly pain that travels towards the back: this can be a sign of acute pancreatitis, which the MHRA highlighted in a January 2026 Drug Safety Update on GLP-1 medicines. If that happens, stop the injection and go to A&E or call 111 rather than waiting for a routine appointment.

People researching whether liraglutide or semaglutide is the right fit often have practical questions about switching or combining them. Our page on taking semaglutide and liraglutide together addresses the clinical reasoning clearly. The short answer is that they are not taken at the same time; a prescriber manages any transition between them.

How to think about which medicine suits your situation

The evidence consistently favours semaglutide over liraglutide on average weight loss, and that advantage is recognised in UK clinical appraisals. But averages are not individual outcomes. The medicine that suits you depends on your medical history, other conditions, what other medicines you take, whether you have tried either previously, and how you feel about daily versus weekly injections. A prescriber weighs all of those factors; no comparison table can do it for you.

For adults wondering specifically whether one or the other is the better starting point, the full clinical comparison on our semaglutide or liraglutide for weight loss page covers the eligibility thresholds, trial data and practical differences in detail. If you are already considering Wegovy specifically, understanding what Wegovy costs privately in the UK is a natural next step, since cost is a real factor in treatment decisions and it is worth knowing what a legitimate private price includes before comparing services.

Whoever reviews your consultation at a regulated pharmacy should be reading your answers as a clinician, not processing them as a form. Our prescribers do exactly that. If you would like to explore whether Wegovy or Mounjaro is right for you, you can check your eligibility with a free consultation and hear back the same day.