What Are the Risks of Taking Wegovy, and When Do They Matter?

What side effects do most people actually get on Wegovy?

The majority of side effects with Wegovy sit in the digestive system. Nausea tops the list by some distance, followed by diarrhoea, vomiting, constipation, indigestion and stomach discomfort. Fatigue, headache and dizziness are also commonly reported. If you have started reading about Wegovy's side-effect profile and found the list daunting, you are not alone, it tends to look alarming on paper.

The practical reality is that these effects are usually mild to moderate, emerge after starting or stepping up the dose, and settle within days to a couple of weeks for most people. They are a signal that the medicine is doing something, not that something has gone wrong. Eating smaller portions, avoiding rich or fatty food and staying well hydrated are the measures prescribers most often recommend during the adjustment phase. The NHS semaglutide medicines page sets out the full list of known side effects alongside their approximate frequency.

Injection-site reactions (redness, bruising, mild swelling) can occur at the site of the weekly injection and usually resolve without any intervention. Rotating the injection site (abdomen, thigh, upper arm) from week to week reduces the likelihood of localised irritation building up.

Are there serious risks that people taking Wegovy need to know about?

Yes. Serious side effects are uncommon, but some carry enough weight that they should not be buried at the bottom of a long list. The most clinically significant are pancreatitis, gallbladder disease and severe allergic reactions.

In January 2026, the MHRA issued a Drug Safety Update specifically drawing attention to acute pancreatitis as a known but infrequent risk for GLP-1 medicines including semaglutide. This is the section to read carefully, symptoms of pancreatitis include severe, persistent abdominal pain that may radiate to the back, sometimes with vomiting. This is distinct from the ordinary nausea of early treatment. If it happens, stop your injection and seek urgent medical help.

Gallbladder problems, including gallstones and cholecystitis, have also been reported. Weight loss itself (through any method) can increase gallstone formation, and GLP-1 medicines slow gastric motility, which may compound this. Symptoms include sharp upper-right abdominal pain, sometimes spreading to the shoulder, often after eating.

Signs of a serious allergic reaction (facial or throat swelling, difficulty breathing, a spreading rash) require emergency attention. Rapid heart rate can occur; if it is sustained or distressing, contact a clinician. Anyone with a personal or family history of medullary thyroid carcinoma or MEN2 should not use Wegovy. These are absolute contraindications, and any prescriber assessing you for the risks of Wegovy specifically will cover them.

When should someone on Wegovy get medical help urgently?

The question every patient deserves a straight answer to. Seek urgent care (call 111 or attend A&E) if you experience any of the following while taking Wegovy:

Severe stomach pain that does not ease, particularly if it radiates to the back. Persistent vomiting or diarrhoea that is stopping you staying hydrated. Signs of kidney problems from dehydration: reduced urine output, dark urine, extreme thirst. Symptoms of gallbladder trouble: sharp right-sided abdominal pain. Any sign of a severe allergic reaction. Sudden changes in vision, which in people with type 2 diabetes may relate to diabetic retinopathy. Thoughts of self-harm or a significant low mood that feels new or unusual.

For anything that concerns you but does not feel like an emergency, our prescribers and aftercare team are available seven days a week, contact the team with any question. Do not stop your injections before speaking to a clinician unless a symptom feels immediately serious. The site FAQs also address common questions about managing side effects between appointments.

Who should not take Wegovy, and what does a proper risk assessment look like?

Wegovy is not suitable for everyone who meets the BMI threshold. Several circumstances make it inappropriate: pregnancy, breastfeeding, or actively trying to conceive. It is not licensed for anyone under 18. A history of pancreatitis, certain gallbladder conditions, medullary thyroid cancer or MEN2 syndrome are among the contraindications a prescriber works through. Some medicines interact with Wegovy or are affected by it, oral contraceptives and certain diabetes medicines require particular attention.

A thorough clinical assessment is not a formality; it is what turns an eligibility check into an actual safety decision. At nume, every consultation is read by a GPhC-registered Independent Prescriber, a real clinician who reviews your full history before any prescription is issued. They are also the right person to talk to about the broader picture: how semaglutide's side effects might interact with your specific circumstances, or whether the overall risk profile of semaglutide fits your situation. If you want to understand your options first, the weight-loss treatments page explains what is available and what the consultation involves. Check your eligibility there, and if you would like a fuller picture before you do, our dedicated Wegovy risks page covers everything a clinician would want you to consider. The conversation about risk is part of it.