Liraglutide vs semaglutide: comparing two GLP-1 medicines for weight loss

You've heard that liraglutide and semaglutide do the same thing, here's where that gets complicated

The idea that all GLP-1 medicines are roughly equivalent is one of the most common assumptions people bring to this comparison. Both drugs activate GLP-1 receptors, slow gastric emptying, and reduce appetite. That much is true. The similarity mostly ends there.

Liraglutide (sold as Saxenda for weight management, or Victoza for type 2 diabetes) must be injected every day. Semaglutide, whether as Wegovy for weight loss or Ozempic for diabetes, is a once-weekly injection. The half-lives are simply different: semaglutide's longer half-life is what makes the weekly schedule possible. For most people managing a busy life, that practical distinction carries real weight.

Trial evidence reflects the gap too. The SCALE trial programme for liraglutide 3 mg reported average weight reductions of around 8% over 56 weeks alongside lifestyle changes. Semaglutide 2.4 mg, in the STEP 1 trial published in the New England Journal of Medicine, produced an average reduction of around 15% over 68 weeks in adults without diabetes. These aren't direct head-to-head comparisons, and individual results vary, but the direction of the evidence is consistent, and our page on how semaglutide and liraglutide compare across those trials sets out the numbers side by side if you want more detail. NICE's appraisals of each medicine reached similar conclusions about the relative magnitude of effect.

Neither result is a guarantee for any individual patient. What you'd actually lose depends on your starting point, your dose tolerance, and whether you sustain the lifestyle work alongside treatment.

What each medicine is licensed for in the UK right now

UK licensing matters enormously here, and it's often muddled online. Liraglutide 3 mg (Saxenda) is licensed in the UK for weight management in adults with a BMI of 30 or above, or 27 or above with at least one weight-related condition. That licence is real and current. Liraglutide 1.2 mg and 1.8 mg (Victoza) are licensed for type 2 diabetes only, not weight loss.

Semaglutide's landscape is broader. Wegovy (semaglutide 2.4 mg weekly injection, titrated from 0.25 mg) holds a UK weight-management licence for the same BMI thresholds. In April 2026, the MHRA also approved a dedicated 7.2 mg single-dose weekly pen for adults with a BMI of 30 or above, following the MHRA's announcement in April 2026. Ozempic (also semaglutide, but at 0.5 mg, 1 mg and 2 mg) is licensed for type 2 diabetes, prescribing it for weight loss is off-label and not what this comparison is about.

If a semaglutide-vs-liraglutide comparison is relevant to you, it's almost certainly the Wegovy vs Saxenda question you're actually asking. The page on the clinical differences between liraglutide and semaglutide goes deeper on mechanism if that's useful.

Side effects, tolerability, and what the profiles actually look like

Both medicines produce a broadly similar side-effect profile because they act on the same receptor. Nausea, diarrhoea, constipation, vomiting, and indigestion are the most common complaints with each. These tend to be most pronounced early in treatment or after a dose increase, then settle for many people over days to a few weeks. The NHS medicines pages for semaglutide cover the full detail.

One practical tolerability point: because liraglutide is dosed daily, its peak-and-trough pattern differs from weekly semaglutide. Some patients find daily dosing creates a more consistent low-level nausea; others find it easier to manage because each dose is smaller. Neither pattern is universally better.

For both medicines, pancreatitis is a known but infrequent serious risk. Severe persistent stomach pain, especially if it radiates to the back, needs urgent medical attention. The MHRA issued a Drug Safety Update on GLP-1 medicines and pancreatitis in January 2026, reinforcing that this should be flagged to any prescriber before treatment starts.

Contraception deserves a note specific to each medicine. Tirzepatide (not semaglutide or liraglutide) is the one that requires adding a non-oral contraceptive method for the first four weeks of treatment and after each dose increase, because it can affect pill absorption. The evidence for that same interaction with semaglutide is less established, but it's worth discussing with your prescriber regardless.

What's available at nume, and how the choice actually gets made

nume prescribes two weight-management medicines: semaglutide (Wegovy) and tirzepatide (Mounjaro). Liraglutide (Saxenda) is not part of our formulary. If you're exploring moving from liraglutide to semaglutide, that's a clinical conversation our prescribers are well-placed to have with you.

The comparison table below sets out the key factual differences. Numbers from trial papers are cited; anything not directly from a named source is described in general terms.

Which of these suits you is not a marketing question. It's a clinical one, answered by looking at your BMI, your health history, any medicines you already take, and how you'd realistically manage a daily versus weekly injection. If you're still weighing up the two options, our page exploring whether semaglutide is the better choice compared to liraglutide for weight loss may help you think it through before your consultation. Our prescribers make that assessment with you. To explore your treatment options and check your eligibility, a free consultation is the starting point, same-day clinical review by a GPhC-registered prescriber, and if approved, treatment dispatched the same day.

If you'd like to read more about semaglutide specifically before deciding, the Wegovy overview covers the full picture, and the cost context for Wegovy in the UK is worth a look if price is part of your thinking.