The difference between liraglutide and semaglutide — and what it means for weight loss

Picture yourself Googling this at 11pm after a GP appointment went nowhere

Your GP mentioned GLP-1 medicines. You've come home and found two names everywhere: liraglutide and semaglutide. Both seem to do something similar. Both seem to involve injections. And the internet isn't being especially helpful about which one is which or whether either one is actually available to you without a referral and a six-month wait.

Here's the short answer: liraglutide (sold as Saxenda for weight management) is a once-daily injection, and semaglutide (sold as Wegovy for weight management) is a once-weekly injection. A newer oral version of semaglutide (Wegovy tablets) was approved in the UK in June 2026. All three are licensed for weight management in adults. But the clinical evidence behind them, the dosing schedules and who can access them differ meaningfully. The NHS medicines page for semaglutide is a good starting point for the official patient-level picture.

One more thing worth knowing before we go further: Ozempic is also semaglutide, and Rybelsus is oral semaglutide, but both are licensed for type 2 diabetes management, not weight loss. If you've seen those names in articles about weight-loss jabs, that's a conflation the MHRA has specifically flagged. On this page we're talking about the weight-loss-licensed versions only.

How each drug works, and where they part ways

Liraglutide and semaglutide share a common mechanism: both activate GLP-1 receptors in the gut and brain, which slows gastric emptying, reduces appetite and helps regulate blood sugar. They are structurally different molecules, though, and those structural differences translate into practical ones.

Liraglutide has a shorter half-life, which is why it needs a daily injection. Semaglutide is engineered with a fatty-acid chain that binds to albumin in the bloodstream, extending its activity so a single weekly dose is enough. That half-life difference also explains the large gap in trial results.

In the STEP 1 trial (68 weeks, adults with obesity, no diabetes) semaglutide 2.4mg produced an average body-weight reduction of around 15%, as published in the New England Journal of Medicine. Liraglutide 3mg produced approximately 8% average weight loss in its pivotal trial (SCALE Obesity and Prediabetes). The semaglutide advantage is substantial, not marginal. NICE's appraisal of semaglutide for weight management (TA875) and its separate appraisal of tirzepatide (TA1026) both acknowledge this gap. Tirzepatide (a dual GIP/GLP-1 agonist) sits above both in the trial hierarchy, but that's a separate comparison.

For a deeper look at how semaglutide specifically stacks up against other GLP-1 agents, the page on the difference between GLP-1 medicines and semaglutide covers the broader class.

Side effects, dosing schedules and what 'titration' means in practice

Because both drugs work on the same receptors, their side-effect profiles are broadly similar: nausea, vomiting, diarrhoea, constipation and indigestion lead the list, and these are typically most noticeable at the start of treatment or after a dose increase. They generally settle. The NHS medicines pages for both drugs describe them in plain language and are worth bookmarking.

The dosing schedules differ more sharply. Liraglutide starts at 0.6mg daily and increases weekly until reaching the 3mg maintenance dose, six weeks of daily injections before you're at therapeutic levels. Semaglutide (Wegovy injection) starts at 0.25mg once weekly and escalates over roughly four-week steps to 2.4mg. Fewer injections, longer steps. A prescriber manages the titration in both cases; the pace is not something to self-adjust.

In January 2026 the MHRA issued a Drug Safety Update for GLP-1 receptor agonists covering acute pancreatitis, severe, persistent stomach pain that may radiate to the back is a reason to seek urgent medical attention. This applies across the class, including both liraglutide and semaglutide. Report any suspected side effects via the MHRA Yellow Card scheme.

If the idea of daily injections is a sticking point, the Wegovy overview explains the weekly injection and the newer tablet alternative in more detail.

What's actually licensed for weight loss in the UK) and where to go from here

Saxenda (liraglutide 3mg) is a licensed weight-management medicine in the UK. We don't stock it at nume, and this page won't point you toward ordering it from us. What we do dispense for weight management is Wegovy (both the weekly injection and the oral tablet approved by the MHRA in June 2026) and Mounjaro (tirzepatide), the only dual GIP/GLP-1 agonist currently licensed for weight management in the UK.

If you're trying to figure out whether semaglutide is the right choice over liraglutide, the honest answer is that the trial evidence consistently favours semaglutide for weight reduction. But trial averages are population figures; individual response varies, and there may be clinical reasons a prescriber would discuss a different option with you. The page comparing whether semaglutide outperforms liraglutide goes further into the evidence. And if you want to see where the newer agents fit in, the dulaglutide and semaglutide comparison, the liraglutide vs semaglutide deep-dive, and the page on how retatrutide differs from semaglutide are all worth reading alongside this one.

For anyone exploring private access, our treatment page shows what's currently available through nume, including current pricing, no subscription, no hidden fees. A real clinician reads your consultation form the same day. If you order on a Monday morning before 12pm, your treatment can be on the way to you before the end of the working day. Check your eligibility and start your free consultation there. Which medicine is appropriate is a clinical decision our prescribers make with you, not before they've spoken to you.