What are the common side effects of Wegovy?

Which side effects do most people on Wegovy actually experience?

The honest answer is that gastrointestinal symptoms are common. In the STEP 1 trial (68 weeks, over 1,900 adults with obesity) nausea, diarrhoea, vomiting, and constipation were the effects reported most frequently among participants taking semaglutide 2.4mg, as documented in the STEP 1 paper in the New England Journal of Medicine. The NHS semaglutide medicines page lists them clearly, and they map closely to what the trial recorded.

Beyond the gut, people also report headache, fatigue, dizziness, and burping. Injection-site reactions (mild redness or irritation where the pen is used) occur in some people too. Keeping the pen in the fridge door and rotating your injection site (abdomen, thigh, upper arm) each week can reduce localised irritation.

The good news about how common Wegovy side effects actually are in practice: most are mild to moderate in severity. They tend to cluster in the first few days after starting or stepping up a dose, then settle. Slowing down eating, staying well hydrated, and avoiding very fatty meals can all help, standard advice your prescriber will go through with you.

When do Wegovy side effects tend to peak, and do they go away?

Timing matters here. The titration schedule for Wegovy is structured precisely to reduce the impact of side effects: doses increase gradually over several months, giving your body time to adjust at each level. Most people find that the most common side effects of Wegovy are at their worst in the first one to two weeks at a new dose, then quiet down.

Nausea in particular tends to follow this pattern. It rarely disappears completely for everyone, but it typically becomes much more manageable over time. If symptoms remain severe or are affecting your ability to eat and drink normally, that is a conversation to have with your prescriber, not something to push through alone.

A small proportion of people do not tolerate semaglutide well and need to pause or stop treatment. That is not a failure; it is the clinical process working as it should. If you want a thorough overview of what the side effects of Wegovy are and which ones are most likely to affect tolerability, our dedicated page covers this in full. In the STEP 1 trial, discontinuations due to side effects were higher in the semaglutide group than placebo but affected a minority of participants overall.

When should you get medical help urgently?

Most side effects are an inconvenience, not a danger. Some are not. Knowing the difference is important before you start any GLP-1 treatment.

Call 999 or go to A&E immediately for: severe, persistent abdominal pain (especially pain that radiates through to your back, with or without vomiting) which can be a sign of acute pancreatitis. In January 2026, the MHRA issued a Drug Safety Update confirming acute pancreatitis as a known, infrequent but serious side effect of GLP-1 receptor agonists including semaglutide. It is rare; it is serious.

Also seek urgent help for: signs of a severe allergic reaction (swelling of the face, throat, or tongue; difficulty breathing), symptoms of severe dehydration from persistent vomiting or diarrhoea (very dark urine, dizziness on standing, inability to keep fluids down), or gallbladder symptoms such as sudden sharp pain in the upper right abdomen. Mood changes or thoughts of self-harm should also prompt immediate contact with a doctor or crisis line. For a fuller picture of Wegovy's side effects profile, including the less common ones, our clinical team has written a dedicated reference.

For anything that worries you but is not an emergency, contact your prescriber. If you are a nume patient, our support team is available seven days a week.

What about side effects specific to overeating or eating habits on Wegovy?

Wegovy reduces appetite substantially, and that change in how you relate to food can itself cause problems if eating habits shift in unhelpful ways. Eating too quickly, eating large portions despite reduced hunger signals, or eating very high-fat meals all tend to worsen nausea and reflux. Some people also notice that alcohol feels stronger or that certain foods they previously tolerated become less comfortable.

There is also a less-discussed pattern worth knowing: some people experience digestive discomfort specifically linked to overeating on Wegovy, the appetite suppression does not always come with an equal reduction in the urge to eat socially or emotionally, and the gut's response to a full meal on semaglutide can be more forceful than before treatment. Smaller, more frequent meals tend to be better tolerated. Our page on semaglutide common side effects goes into more detail on how the drug affects digestion and what practical steps can help manage these reactions day to day. Your prescriber or a registered dietitian can advise on practical adjustments; the frequently asked questions section on our site covers some of the common dietary queries too.

If you are considering Wegovy and want to understand the full suitability picture, including how side effects are managed, speak to our prescribers, the consultation is free and covers this in detail.