Should you take your Wegovy shot when you're sick?

When being sick probably doesn't change anything

A question our prescribers hear most weeks goes roughly: 'I've got a rotten cold, should I skip my injection?' For most people, the answer is no. Upper respiratory infections, sore throats, mild fever and similar illnesses don't interact with semaglutide in a clinically significant way. Your digestive system is largely unaffected, which means the risk of worsening your illness by injecting is low. You can read more about how Wegovy behaves in the body on the Wegovy overview page, but the short version is that its main effects operate on the gut-brain appetite axis rather than the immune system.

The practical question is whether you feel well enough to manage the routine: clean hands, swab the site, inject at the right depth. If you're genuinely prostrate in bed with a high fever and feel too unwell to concentrate, postponing by a day or two is reasonable. The licensed schedule permits this, the Patient Information Leaflet confirms that a missed dose can be taken up to 5 days late; after that, skip it and continue from your next scheduled day.

If fatigue is your main symptom on injection day, that's worth knowing about separately. Post-injection tiredness is common in its own right, as covered in detail for anyone trying to make sense of feeling tired after their Wegovy shot. Being under the weather can make that tiredness feel more pronounced than usual.

When you should seriously consider waiting

Gastrointestinal illness is a different matter. Wegovy's most common side effects are GI-led: nausea, vomiting, diarrhoea and indigestion are all listed by the NHS as typical responses, particularly after starting or after a dose increase. If you already have a stomach bug producing those same symptoms, injecting on schedule can compound them significantly. The concern isn't theoretical. Repeated vomiting or diarrhoea, combined with the gastric-slowing effect of semaglutide, raises a genuine dehydration risk. Kidneys need adequate hydration to function well, and GLP-1 medicines can intensify fluid loss in that context.

The January 2026 MHRA Drug Safety Update on GLP-1 medicines flagged acute pancreatitis as an infrequent but serious risk, severe, persistent stomach pain that reaches the back, with or without vomiting, is the symptom to watch for and requires urgent medical assessment. If you're not sure whether your stomach pain is a bug or something more significant, the full rundown of Wegovy injection side effects sets out what typically resolves on its own and what warrants a call to 111.

In practical terms: if you're vomiting on injection day or haven't been able to keep fluids down reliably, delay the shot. Use the 5-day window if you feel better within a few days. If you don't feel better within that window, contact your prescriber rather than guessing. You can also find broader guidance on what to do when you feel sick on Wegovy as a treatment in general.

Making the call: a practical framework

The clearest way to frame this decision is to separate symptom type from symptom severity. Cold-type illness (respiratory, no vomiting, fluids going in normally): carry on, or delay by a day purely for comfort. GI illness with active vomiting or diarrhoea: hold the injection, prioritise rehydration, and reassess once your gut has settled. GI illness severe enough that you can't keep fluids down after 24 hours: seek medical help regardless of whether you've injected or not, that's the dehydration threshold.

The NHS patient information for semaglutide reinforces that missed doses have a structured recovery route built into the schedule, so there's no need to force an injection when you're genuinely unwell. You can check the NHS guidance on semaglutide for the full missed-dose instructions as they appear in the official guidance.

One thing worth flagging: if you're on Wegovy and also taking other medicines for your illness (antivirals, antibiotics, or even over-the-counter remedies) some of those can interact with how your gut absorbs oral medications. The gastric-emptying effect of semaglutide is relevant here. Read more about what makes Wegovy safe to use in different circumstances, and always tell any prescriber treating you for a separate condition that you're on a GLP-1 medicine. For the full picture on how this medicine behaves over time, the Wegovy side effects guide covers the longer-term pattern beyond the first few weeks.

If you're not yet on Wegovy and are weighing up whether it's the right treatment for you, the cost and process of private treatment are outlined on the treatment page. And if you'd like a prescriber to look at your specific circumstances, that conversation starts with a free consultation, reviewed the same day by a real clinician.