Wegovy and Ozempic side effects: what's the same, what's different

The misconception worth clearing up first: same drug doesn't mean identical experience

A lot of people assume that because Wegovy and Ozempic are both semaglutide, taking one or the other feels exactly the same. That's not quite right. The molecule is identical (a GLP-1 receptor agonist that slows gastric emptying and reduces appetite signals) but the doses are different, and dose is probably the biggest driver of how pronounced the side effects are.

Ozempic's maintenance doses for diabetes management run up to 2mg weekly. Wegovy's standard maintenance dose is 2.4mg, and the MHRA approved a 7.2mg maintenance dose option in early 2026. Higher doses mean stronger appetite suppression, but they also mean the gastrointestinal system is working harder to adapt. The NHS patient information on semaglutide notes the same core side-effect categories across formulations, with severity linked to how quickly the dose climbs.

This matters practically: someone who took Ozempic for diabetes and found it tolerable shouldn't assume Wegovy at 2.4mg will feel identical. The biology is shared; the intensity can differ. That's not a reason to avoid either medicine, it's a reason to titrate carefully and to have a prescriber who actually checks in.

Ozempic is licensed in the UK for type 2 diabetes, not weight loss. If you want to understand what side effects Ozempic and semaglutide can cause, our dedicated page covers the full documented profile. If you're looking at weight management options, our overview of Wegovy for weight loss covers what the licensed treatment actually involves.

What the shared side-effect profile looks like day to day

Because both medicines work through the same receptor, the side-effect categories are largely the same. Nausea is the one most people mention first, often strongest in the first few days after a new dose, then settling. Diarrhoea, constipation (sometimes alternating), indigestion, reflux, burping, and fatigue are all in the documented profile for semaglutide across its formulations.

Headache and dizziness appear less often. Injection-site reactions are usually minor: mild redness or itching that clears quickly. Most of these effects are most noticeable after a dose increase and tend to fade within days to about two weeks as the body adjusts.

What's different is the frequency and intensity data. Trial populations, doses, and follow-up periods differ between the Ozempic trials (SUSTAIN programme) and the Wegovy trials (STEP programme). In STEP 1, published in the New England Journal of Medicine, GI side effects were the most common reason for discontinuation at the 2.4mg maintenance dose. That's context, not a deterrent, most participants continued and the effects were generally transient.

For a fuller look at what Wegovy's documented side effects involve, if you're asking whether Wegovy has side effects and what they actually are, that page goes into detail on each category, including the Wegovy side-effects page and the less-discussed effects some people notice in their face.

When to get medical help, the signs that need more than waiting

Most GI side effects are unpleasant rather than dangerous. A few signs warrant prompt medical attention.

Severe, persistent stomach pain that spreads toward the back, with or without vomiting, can indicate acute pancreatitis. In January 2026 the MHRA issued a Drug Safety Update for GLP-1 medicines specifically flagging this: it's infrequent but serious, and the right response is to stop the medicine and seek urgent medical help rather than wait it out. The MHRA Drug Safety Updates page holds the full communication.

Other situations that need a clinician rather than reassurance: signs of an allergic reaction (swelling of the face, lips or throat, difficulty breathing), symptoms of dehydration from persistent vomiting or diarrhoea (dark urine, dizziness on standing, inability to keep fluids down), or gallbladder symptoms such as pain in the upper right abdomen. Low mood or thoughts of self-harm should also prompt contact with a doctor, not just a pharmacy.

If you're on Wegovy and something doesn't feel right, our aftercare team is available seven days a week. And patients can report suspected side effects directly to the MHRA via Yellow Card, the link is in the safety facts above.

What is actually licensed for weight loss in the UK, and how to access it safely

Ozempic is not licensed for weight management in the UK. Prescribing it for that purpose is off-label, and the MHRA has been clear that it is not assessed for quick or cosmetic weight loss. Any seller offering it specifically as a weight-loss treatment is working outside the licensed indication.

The two medicines licensed for weight management in the UK are Wegovy (semaglutide at 2.4mg and now up to 7.2mg) and Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist with a different mechanism and a separate side-effect profile. Our weight-loss treatments overview explains both.

Both are prescription-only medicines. The legal route is a clinical assessment with a GPhC-registered prescriber who reviews your health history, confirms eligibility, and can answer questions about what the side-effect experience actually looks like for someone with your particular profile. Prices vary by dose and provider; a realistic overview is on the Wegovy pricing page.

If you'd like to discuss suitability (including questions about side effects) our prescribers cover that as part of the free consultation. Check your eligibility to get started.