The negatives of Wegovy: what you need to weigh up honestly

The side effects that most people actually experience

Gastrointestinal symptoms are by far the most commonly reported Wegovy negatives. Nausea is the one patients mention first, but the full picture includes vomiting, diarrhoea, constipation, burping, reflux and a general feeling of stomach heaviness that some people find hard to manage alongside daily life. In the STEP 1 trial, published in the New England Journal of Medicine, around 74% of participants on semaglutide 2.4mg reported nausea at some point, compared with about 31% of the placebo group.

For many people these symptoms are worst in the first couple of weeks after each dose increase and then settle. For others they persist longer or return. Fatigue, headaches and dizziness are also reported, though less frequently. Injection-site reactions — redness, mild bruising, localised discomfort — occur in a smaller number of users.

More serious, and less common, are the risks the MHRA Drug Safety Updates flag. In January 2026, the MHRA drew attention to acute pancreatitis as a known side effect of GLP-1 medicines including semaglutide. The signal here is severe, persistent stomach pain that may radiate towards the back, with or without vomiting. That warrants urgent medical attention, not watchful waiting. Gallbladder problems, including gallstones, are also recognised.

Skin reactions are less often discussed but can occur; our page on hives from Wegovy covers what an allergic-type reaction might look like and when to escalate.

Practical constraints that affect everyday life

Wegovy is a once-weekly injection, which suits most people once they are used to it, but the logistics are worth thinking through. The pen requires refrigeration between 2°C and 8°C. Travel, power cuts and prolonged room-temperature exposure all raise questions about storage; the exact permitted out-of-fridge window is set out in the Patient Information Leaflet and varies, so checking it before a holiday matters.

Speaking of holidays: if you typically order repeat treatment around a particular point in the month, a bank holiday falling on a Monday in August or a delivery delay during December can interrupt your schedule. That is worth factoring into planning from the start, not discovering when you are already mid-treatment.

Women using the oral contraceptive pill should be aware that starting tirzepatide (a different medicine, but relevant for comparison) affects pill absorption; current NHS guidance suggests no equivalent interaction for semaglutide, but this is worth confirming with your prescriber given the wider guidance on weight-management injections from NHS England. HRT users, people planning surgery and anyone trying to conceive all have specific conversations to have with a clinician before starting.

Wegovy is not recommended in pregnancy, during breastfeeding or if you are actively trying to conceive. It is not licensed for under-18s. These are firm boundaries, not cautions to weigh up.

Who can actually access it, and for how long

Access is one of the more uncomfortable Wegovy negatives because it collides with expectation. On the NHS, NICE guidance TA875 recommends semaglutide only within specialist weight management services, for a maximum of two years, for adults with at least one weight-related comorbidity and a BMI of 35 or above (lower thresholds apply for some ethnic backgrounds). Waiting times for specialist services can be long, and not everyone who would benefit clinically will qualify under current NHS criteria.

In the private market the medicine is available via a legitimate prescription route, but cost accumulates quickly over months. Our Wegovy price guide sets out the honest picture of what private treatment currently costs and what that figure should include, a clinical assessment, a prescription, dispensing, delivery and aftercare access. Providers who advertise only the headline pen price without those components attached are worth scrutinising.

Weight can return after stopping. This is not a failure of the patient; it is a feature of the medicine's mechanism. Semaglutide works while you are taking it. For people who cannot stay on treatment long-term, that biological reality is a significant limitation worth discussing before starting. Our wider overview of semaglutide and the dedicated Wegovy page go into the mechanism in more detail if you want to understand why that happens.

Weighing the negatives against the alternatives

Framing the Wegovy negatives in isolation is only useful up to a point. The more useful question is: how do they compare to your other options? Our page on Wegovy alternatives covers tirzepatide and other licensed UK routes. A separate page looks at the broader side-effect profile of semaglutide across both of its licensed forms, which is worth reading alongside this one.

There are also newer developments worth knowing about. The MHRA approved a higher 7.2mg dose of semaglutide in early 2026, and the evidence from trials at that dose shows average weight loss closer to tirzepatide's results; our report on the MHRA's approval of the stronger Wegovy pen summarises what changed and for whom it may be suitable. That does not eliminate the side-effect profile, but it changes the benefit side of the equation for some patients.

The decision about whether Wegovy's negatives are outweighed by its potential benefits is genuinely individual. It depends on your weight, your health conditions, your tolerance for GI side effects and your practical circumstances. A prescriber who reviews your full picture (not a short questionnaire scored by software, but a proper clinical assessment) is the person best placed to help you reach that decision. If you would like that conversation, you can check your eligibility with our clinical team.