The Real Risks of Taking Wegovy — and How to Spot Them Early

You've just started Wegovy and your stomach is in revolt. Here's what's normal

For a lot of people, the first few weeks on Wegovy feel like a negotiation with their digestive system. Nausea is by far the most frequently reported effect, not in a dramatic way for most, but enough to notice, especially on the day of or day after an injection. Loose stools, constipation (sometimes both at different points), indigestion, burping, and a general feeling of fullness that sits slightly wrong are all part of the same pattern. These effects are the body adjusting to a medicine that slows how quickly food leaves the stomach.

The NHS medicines page for semaglutide sets out this profile clearly: GI effects are common, tend to be most noticeable after starting or after a dose step up, and often settle over a couple of weeks. They're uncomfortable, not dangerous in themselves. Staying hydrated helps. Eating smaller portions, avoiding fatty meals, and not lying down straight after eating all make a practical difference. One simple habit worth building: before each weekly injection, take thirty seconds to note how you've felt that week (any symptoms, any patterns) so you can discuss them accurately at your next clinical review. If the nausea is severe enough to prevent you eating or drinking, contact your prescriber or a pharmacist rather than waiting.

Headache, fatigue, and dizziness also appear in the common side-effect data. For most people these are brief and mild, but they're worth tracking, particularly if they persist beyond the initial adjustment window. You can read a more detailed breakdown of what to expect from the side effects of taking Wegovy on our Wegovy side effects page.

When the risks of Wegovy become something you shouldn't sit with at home

Serious side effects from Wegovy are uncommon, but they exist, and recognising them matters. In January 2026, the MHRA issued a Drug Safety Update for the class of GLP-1 medicines (including semaglutide) specifically drawing attention to acute pancreatitis. It is rare, but it can be serious. The symptom to know: severe, persistent pain in the middle or upper abdomen that may spread through to the back, with or without vomiting. That's not garden-variety nausea from your injection. If that happens, stop eating and drinking and go to A&E or call 999. Don't wait to see if it passes.

Gallbladder problems (gallstones or inflammation) are another known risk with GLP-1 medicines, more so when weight loss is rapid. The signs overlap with pancreatitis to some degree: upper abdominal pain, particularly after eating, sometimes with a fever or jaundice. Again, these need prompt medical assessment. Severe dehydration from prolonged vomiting or diarrhoea can strain the kidneys, so if GI symptoms are bad enough that you can't keep fluids down, get advice that day rather than managing it alone.

Allergic reactions are rare but possible: swelling around the face, throat, or tongue, difficulty breathing, or a widespread rash should prompt calling 999. For a fuller picture of the specific risk landscape, the risks of taking Wegovy page goes deeper on each category, and our page covering the risks of taking Wegovy for weight loss looks specifically at how those risks apply in a weight-management context.

The risks that are easy to overlook (contraception, pregnancy, and interactions

Because Wegovy slows gastric emptying, it can affect how reliably oral medicines are absorbed) and that includes the contraceptive pill. NHS England's weight-management guidance is explicit: women taking oral contraceptives should discuss switching to a non-oral method (such as an implant, coil, or injection) or using additional barrier contraception while on Wegovy. This is an easy thing to forget when the conversation is focused on weight loss, but it has real consequences.

Wegovy is not recommended during pregnancy, while breastfeeding, or when actively trying to conceive. If your circumstances change, talk to your prescriber promptly. The same applies if you are scheduled for surgery: anaesthetists need to know you are on a GLP-1 medicine because of the aspiration risk linked to slowed gastric emptying. Carry the name of your medicine and dose with you if you're heading into hospital.

The picture is slightly different from tirzepatide in one respect: for semaglutide (Wegovy), there isn't the same established evidence of reduced oral contraceptive absorption that exists for tirzepatide, but the precautionary advice still stands, if in doubt, discuss with your prescriber before your first dose rather than after. Our semaglutide risks page covers the wider semaglutide risk profile if you want to read further, and you can also find a focused overview of the Wegovy risks most relevant to new starters on its dedicated page.

Reporting a side effect, and getting support through a regulated service

Any suspected side effect from Wegovy can be reported to the MHRA directly, by you, through the Yellow Card scheme. You don't need a doctor to do it. Reporting matters, it's how regulators spot signals that don't show up in clinical trials, and how guidance like the January 2026 pancreatitis update comes to exist.

Through a regulated online pharmacy like ours, you also have access to clinical aftercare throughout your treatment, not just at the point of prescribing. That means questions about side effects don't have to wait until your next appointment. Wegovy is a prescription medicine that requires proper clinical assessment, a prescriber reviews your full picture before any treatment is issued, and that conversation covers your individual risk profile, not just the average from a trials population. If you're weighing up whether the risks are right for your situation, that's exactly what the consultation is designed to help you decide. You can read about our clinical team on the prescriber profile page. When you're ready, start your free consultation and speak to our prescribers about whether Wegovy is suitable for you.