Switching from Liraglutide to Semaglutide for Weight Loss

What the trial data shows about weight loss on each medicine

The published evidence places these two medicines in different performance brackets. The STEP 1 trial, published in the New England Journal of Medicine, found that adults taking semaglutide 2.4mg weekly lost an average of around 15% of body weight over 68 weeks alongside lifestyle support. Liraglutide 3mg daily, in its own phase 3 programme (the SCALE trials), produced average losses in the region of 5–8% over 56 weeks, broadly consistent with what prescribers see in practice.

A NICE appraisal of semaglutide (TA875) concluded it was clinically effective and cost-effective within specialist weight management services, in part because its effect size meaningfully exceeded what earlier GLP-1 therapies had achieved. That appraisal did not include a direct head-to-head trial between the two medicines, so the comparison relies on cross-trial data; nonetheless, the direction is consistent across independent analyses.

For people who have been on liraglutide and found the results modest, or who struggled with the daily injection burden, the switch to a once-weekly medicine with a larger evidence base is often worth exploring. If you are also considering how Wegovy compares with other weekly injectables, our Wegovy vs Trulicity comparison page covers that question in detail, alongside our liraglutide vs semaglutide comparison page.

What switching actually involves) dosing, timing and the wash-out question

Switching GLP-1 medicines is not simply a case of stopping one pen and starting another the next day. Liraglutide is titrated daily from 0.6mg up to the 3mg maintenance dose over several weeks; semaglutide starts at 0.25mg weekly and is stepped up by a prescriber over approximately four months to the 2.4mg maintenance dose. The titration schedules, injection timing and the question of whether a wash-out period is needed are all clinical decisions, not something to work out from a website.

The practical detail of how the dose ladder changes when moving between these medicines is covered on our liraglutide-to-semaglutide dosing page. What matters here is the principle: a prescriber needs to review your current dose, how well you tolerated liraglutide, any relevant medical history and your weight trajectory before recommending a switch. Restarting a titration from the beginning is standard, it keeps gastrointestinal side effects manageable as your system adjusts to a different molecule.

One practical note people often raise: liraglutide requires daily injections, which many people store in the fridge door and work around every morning. Moving to a once-weekly routine removes that daily step. The pen still needs refrigeration between uses, but the weekly rhythm is something most people find easier to sustain.

Side effects, eligibility and what stays the same when you switch

Both medicines share a GLP-1 mechanism, so the side-effect profile overlaps significantly. Nausea, loose stools, constipation, reflux and reduced appetite are common to both, typically most noticeable in the first few weeks of treatment or after a dose increase, and usually settling as the body adjusts. The NHS patient information for semaglutide sets out what to watch for in plain language.

Eligibility thresholds are broadly the same: a BMI of 30 or above, or 27 or above alongside at least one weight-related condition such as high blood pressure, type 2 diabetes, dyslipidaemia or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance. Pregnancy, breastfeeding and active plans to conceive are contraindications for both medicines; under-18s are not within the licensed populations for either.

If you were previously on liraglutide through an NHS pathway, it is worth knowing that Wegovy on the NHS requires referral into a specialist weight management service under NICE TA875, and waiting lists in many areas are long. A private route through a regulated online pharmacy (one you can verify on the GPhC register) is an alternative that does not require a referral, subject to clinical suitability assessed at consultation.

What IS available through nume, and how to explore it

Liraglutide (Saxenda) is not part of our formulary. Wegovy (semaglutide 2.4mg injection) is. So is Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist that produced average weight loss of around 20–21% at its highest dose in the SURMOUNT-1 trial, a larger effect than either liraglutide or the standard semaglutide dose. If you are weighing up the options across the newer medicines, our overview of semaglutide versus liraglutide and the main Wegovy treatment page cover the ground in more detail.

For context on what private treatment costs, our Wegovy pricing page sets out what is included in a single transparent price, consultation, prescription, delivery and 7-day aftercare, with no subscription and no auto-renewal. Every repeat order goes through a fresh clinical review before anything is dispatched.

Which medicine suits you is not a question this page can answer, that is genuinely a clinical decision made with a prescriber who knows your history. Our team at nume reviews every consultation personally the same day. If you would like to explore whether Wegovy is appropriate following your time on liraglutide, check your eligibility with a free consultation.