Can Wegovy Give You a Fever?

Is fever an actual listed side effect of Wegovy?

The short answer is no. The NHS medicines guidance for semaglutide, which covers Wegovy, does not include fever on its list of recognised side effects. Neither does the UK Summary of Product Characteristics (SmPC). The commonly reported reactions in clinical trials were gastrointestinal in nature: nausea, diarrhoea, constipation, vomiting, and indigestion being the most frequent, particularly in the early weeks of treatment or after a dose step-up.

That does not mean nobody ever runs a temperature while on Wegovy. If you want to understand exactly why some people report feeling feverish after an injection, our semaglutide fever page looks at the possible explanations in detail, including how GI discomfort, dehydration from vomiting or diarrhoea, and unrelated illnesses can all play a role. The medicine slows gastric emptying and reduces appetite; neither mechanism has a direct pathway to raising core body temperature.

If you want a quick self-check habit, take your temperature before your next weekly injection and note the reading. You will then have a baseline that makes it far easier to interpret any temperature change that follows. It takes under a minute and gives you something concrete to share with a clinician.

For a broader overview of how semaglutide works and what its confirmed side-effect profile looks like, the semaglutide information page covers the mechanism and the trial evidence in plain language.

When should a temperature during Wegovy treatment concern you?

There is one scenario where a raised temperature alongside other symptoms must be taken seriously: acute pancreatitis. In January 2026 the MHRA issued a Drug Safety Update for GLP-1 receptor agonist medicines, highlighting pancreatitis as an infrequent but potentially serious adverse reaction. The warning signs are severe, persistent abdominal pain that may radiate through to the back, often accompanied by nausea and vomiting. Fever can be part of the clinical picture of pancreatitis, so if you experience those stomach symptoms alongside a raised temperature, seek urgent medical help rather than waiting to see whether it settles.

Gallbladder problems are another recognised complication with GLP-1 medicines, gallstones or gallbladder inflammation can also produce fever. Pain in the upper right abdomen, especially after eating, combined with a temperature, is a reason to contact your GP promptly rather than attributing it to Wegovy's usual GI effects.

Dehydration from prolonged vomiting or diarrhoea can itself cause a mild rise in temperature. If you have been struggling to keep fluids down for more than 24 hours, that alone is a reason to seek advice. You can read more about the specific guidance on fever while on Wegovy for a closer look at what the evidence says about temperature and this medicine.

What about injection-site reactions, can those cause a fever?

Local injection-site reactions are a known, listed side effect of Wegovy: redness, bruising, swelling, or mild discomfort at the injection site are all reported. These are typically minor and resolve quickly. A significant infection at the injection site (which is uncommon with proper technique) could theoretically produce a systemic temperature, but this would require clear signs of local infection: spreading redness, warmth, pus, or worsening pain beyond the first day or two.

Good injection practice reduces this risk considerably. Rotating between the abdomen, thigh, and upper arm with each weekly dose, and using a fresh needle each time, are the standard recommendations. The guide to injecting Wegovy correctly covers technique in full if you want to make sure your process is right.

If a site looks infected rather than just bruised, do not self-manage it. Contact your GP, and reach our clinical team through the aftercare line if you are a nume patient.

Should you stop Wegovy if you develop a fever?

Not automatically, no. A coincidental viral illness (a cold, flu, a stomach bug) is far more likely to explain a fever in any given week than the medicine itself. The NHS guidance for semaglutide on nhs.uk does not recommend stopping treatment for a mild, self-resolving temperature. Pausing your weekly injection while acutely unwell is sometimes sensible from a practical standpoint (GI illness on top of GI side effects can compound dehydration), but this is a decision to make with your prescriber rather than alone.

What you should not do is ignore a high temperature (above 39°C) combined with severe pain, rapid heart rate, or confusion. That combination, regardless of whether you take Wegovy, calls for 999 or A&E rather than a check of the medicine's leaflet.

For any questions about your individual treatment, including symptoms you are unsure about, the Wegovy treatment page explains the full clinical picture, and our aftercare team is available seven days a week. If you are still weighing up whether Wegovy is right for you, including practical questions such as whether you can give blood while on Wegovy, our prescribers can help, check your eligibility through a free consultation and have those questions answered by a real clinician.