Wegovy vs Saxenda Side Effects Compared

The biggest misconception: Saxenda has 'fewer' side effects because it's older

It's a common assumption, Saxenda has been around since 2015, so it must be better understood and gentler. That's not what the clinical data shows. Both medicines are GLP-1 receptor agonists, which means they slow how fast the stomach empties and reduce appetite via the same hormonal pathway. The side-effect profiles are strikingly similar as a result. Nausea, vomiting, diarrhoea, constipation, indigestion and headache appear in both medicines' prescribing information and are reported at broadly comparable rates. The difference isn't really one medicine being milder than the other, it's about dosing frequency and how the titration schedule affects tolerability. Saxenda is injected daily; Wegovy is once weekly. Some people find that a daily small dose produces steadier, lower-peak drug levels and therefore slightly less pronounced nausea at any one moment. Others find the weekly rhythm of Wegovy easier to stick to, because side effects tend to cluster in the day or two after injection and then settle. The full side-effect picture for Wegovy is worth reading before drawing conclusions either way.

Side by side: what the evidence shows for each

The table below draws on data from the pivotal trials and licensed prescribing information for both medicines. Numbers are approximate and come from different trial designs, so direct comparison requires care.

The MHRA Drug Safety Update (January 2026) is worth reading if you want the regulator's current position on GLP-1 and pancreatitis risk, it covers both medicines.

Saxenda and weight loss licensing in the UK, and why it matters here

Saxenda is licensed for weight management in the UK, so it is a legitimate comparator. However, nume does not dispense Saxenda. That's not an arbitrary gap in our range: the evidence consistently shows Wegovy produces greater average weight loss than liraglutide, and the newer tirzepatide (Mounjaro) shows even larger reductions in head-to-head data. If you're researching Saxenda because a prescriber mentioned it, or because you've read about it online, the most useful thing this page can do is direct you toward the medicines we can actually offer. Both Wegovy and Mounjaro are licensed UK weight-management treatments available through a private prescription at nume. The treatment overview page sets out how the two compare on efficacy and how a prescriber decides between them based on your health picture. Worth a look before your consultation.

One practical note that often goes unmentioned: Saxenda requires daily refrigeration throughout, it lives in the fridge door between every injection. Wegovy also needs refrigeration but the once-weekly rhythm means you handle it far less often, and the NHS notes a limited period at room temperature for travel (always check the patient information leaflet for the exact window). For people whose routine makes daily fridge access tricky, that's a real-world consideration. If you're starting out on Wegovy, understanding what to expect from the 0.5mg starting dose can help you plan your routine and manage those early weeks with more confidence. The question of why some people experience very few side effects on Wegovy touches on this too, adherence to routine plays a bigger role than most people expect.

When to get medical help, whichever medicine you're on

Nausea and loose stools are expected. Severe, persistent stomach pain that radiates to your back is not, that warrants urgent medical attention because it can signal acute pancreatitis, a rare but serious complication flagged by the MHRA for all GLP-1 medicines. The same applies to signs of a serious allergic reaction (swelling of the face, throat or tongue, difficulty breathing), significant dehydration from prolonged vomiting, or any sudden changes in mood or thoughts of self-harm. The MHRA Yellow Card scheme lets patients report suspected side effects directly, and doing so genuinely helps regulators track real-world safety signals. Our prescribers are available seven days a week through aftercare if you have concerns about how a medicine is sitting with you. If something feels seriously wrong, call 111 or attend A&E, don't wait for an online reply. You can also read more on managing side effects from Wegovy for practical day-to-day guidance.

Which medicine is right for you (Wegovy, Mounjaro, or something else entirely) is a clinical decision that depends on your health history, current medicines and what your body is likely to tolerate. If you are weighing up your options, comparing how Mounjaro and Wegovy differ in their side-effect profiles is a good place to start that thinking before your consultation. Our prescribers work through that with you. Speak to our prescribers through a free consultation to start that conversation.