Wegovy Warnings Explained: What Official Guidance and Trial Data Tell You

What the MHRA's 2026 safety update flags about pancreatitis

The most significant regulatory warning to emerge since Wegovy reached UK pharmacies came on 29 January 2026, when the MHRA published a Drug Safety Update confirming that acute pancreatitis is a known (and occasionally serious) risk across the GLP-1 class. The signal had existed in the original semaglutide trial data, but the 2026 update formalised prescriber guidance in the UK context. You can read the full communication through the MHRA Drug Safety Update index on GOV.UK.

The symptom to act on immediately is severe stomach pain that doesn't pass, particularly if it radiates towards the back, with or without vomiting. This is the pattern associated with pancreatitis, and the advice is unambiguous: stop the injection and get medical help the same day. It is an uncommon event, but uncommon is not the same as impossible, and waiting to see whether the pain settles is the wrong call here.

Two other abdominal warnings sit alongside this. Gallbladder problems (including gallstones and inflammation) appear at a slightly elevated rate in people taking semaglutide, probably because rapid weight loss itself affects bile composition. And because nausea, vomiting and diarrhoea are common early on treatment, dehydration is a real concern; severe or prolonged GI illness needs medical input to avoid kidney strain. A fuller breakdown of the GI side-effect picture is covered on the side effects of taking Wegovy page.

Warnings around pregnancy, contraception and reproductive planning

Wegovy carries a clear warning against use in pregnancy, and the NHS advises that the medicine should not be taken while breastfeeding or when actively trying to conceive. The MHRA guidance asks women to use effective contraception during treatment and for a wash-out period afterwards before attempting conception, the prescriber will confirm the timeline relevant to your situation, since it differs by medicine.

Contraception itself deserves a specific note for semaglutide. GLP-1 medicines slow gastric emptying, which can in principle affect how consistently oral contraceptives are absorbed. The NHS England guidance on weight-management injections addresses this directly for tirzepatide (where the evidence is stronger), and prescribers take the same cautious approach with semaglutide. If you rely on the pill, raising this with your prescriber before starting (or before a dose increase) is sensible, not overcautious.

For anyone who uses transdermal HRT (patches or gels), the oral-absorption concern applies similarly. Discussing your current hormone regimen with a prescriber before starting Wegovy is part of a thorough clinical assessment, not an optional extra. Under-18s: semaglutide for weight management is not licensed for people under 18 in the UK.

The side-effect warnings most patients actually encounter

The STEP 1 trial (68 weeks, 2.4mg semaglutide versus placebo, published in the New England Journal of Medicine) showed that gastrointestinal effects were by far the most commonly reported side effects. Nausea affected a substantial proportion of participants, particularly in the first weeks and after each dose step. Vomiting, diarrhoea, constipation, burping, and indigestion completed the picture, and if you want to understand why burping on Wegovy happens and how to manage it, the causes are more specific to GLP-1 mechanisms than most people expect. The Wegovy side effects overview goes into more detail on frequencies and management.

In practice, most people find these effects are worst on the day of injection and in the two to three days that follow, then fade as the dose settles in. Eating slowly, avoiding very fatty or large meals, and staying well hydrated all help. The dose-escalation schedule exists precisely to reduce this burden, the 0.25mg starting dose is not where any meaningful weight loss begins; it is four weeks for your system to adjust before the first increase.

A smaller number of people report headaches, fatigue, or dizziness, particularly early on. Injection-site redness or discomfort is possible but usually mild and transient. If you notice swelling of the face, lips or throat, a fast heartbeat, or difficulty breathing, these are signs of a possible allergic reaction and need urgent attention. The NHS semaglutide medicines page lists the full spectrum of known effects and sets out clearly when to call 111, when to go to A&E, and when to raise something at your next appointment.

How a clinical assessment handles these warnings before you start

Understanding the official warnings is only half the picture. The other half is knowing they are exactly what a prescriber works through before approving treatment, and reading through the full semaglutide warnings before your consultation means you can answer those questions more accurately and flag anything relevant to your own history. At a regulated UK online pharmacy, every new Wegovy consultation involves the prescriber checking your medical history for conditions (including a personal or family history of medullary thyroid carcinoma, MEN2 syndrome, pancreatitis, or significant GI disease) that would make semaglutide unsuitable or require particular caution.

That review is not a box-tick. A prescriber reading your answers can ask follow-up questions, flag something for GP input, recommend a different starting approach, or decline to prescribe where the risk-benefit balance doesn't stack up. If you're already on treatment elsewhere and considering switching, our guide to whether Wegovy is safe covers what transfer patients should expect from a responsible clinical handover.

It is also worth being aware that anyone who finds a supplier offering semaglutide without a prescription is being offered something that has bypassed this entire process, and the MHRA has linked such sources to counterfeit pens that have caused hospitalisations. For context on the broader safety landscape for buying GLP-1 medicines in the UK, the Wegovy access page explains the regulated route.

If you have read the warnings and want to understand whether you are a suitable candidate, the straightforward next step is a free consultation with a GPhC-registered Independent Prescriber. A real clinician reviews your answers (not software) usually on the same day you submit. Check your eligibility with the nume clinical team and get a clear answer before committing to anything.