Is the Wegovy Shot Safe? What the Evidence Actually Shows

Step 1: What typically happens in the first few weeks of treatment

Wegovy (semaglutide) is introduced slowly, starting at 0.25mg weekly and moving up in stages (roughly every four weeks) toward the 2.4mg maintenance dose. That gradual titration exists partly for tolerability. The body's GLP-1 receptors take time to adjust to a medicine that slows gastric emptying and dampens appetite, and the most common side effects cluster around this early period.

Nausea is what people mention most often. It can also show up as bloating, burping, an upset stomach, loose stools or constipation, sometimes a mix that shifts from week to week. Headaches and low-grade tiredness are reported too. Our page on Wegovy's full side-effect profile goes through each one in detail. Most people find the worst of it settles within the first two to four weeks on a given dose, although that varies from person to person.

One practical check that takes under a minute: scan the batch number printed on your pen against the product details on the electronic Medicines Compendium, where the full Wegovy Patient Information Leaflet is published. Anything that doesn't match, don't use it and contact your prescriber.

If nausea is persistent, eating smaller meals, avoiding fatty or very spicy food and staying well hydrated all help. Your prescriber can also advise whether a slower titration would suit you better, that conversation is entirely normal and our clinical team welcomes it.

Step 2: Recognising the side effects that need prompt medical attention

Most Wegovy side effects are uncomfortable rather than dangerous. A handful are not. Knowing the difference matters.

Acute pancreatitis is a known, infrequent but serious risk with GLP-1 medicines. In January 2026, the MHRA issued a Drug Safety Update specifically highlighting pancreatitis as a risk requiring awareness: if you develop severe stomach pain that does not ease, especially pain that spreads into your back, with or without vomiting, stop treatment and get medical help the same day. Do not wait to see if it passes.

Other signs to act on quickly include: sudden or severe abdominal pain that could indicate a gallbladder problem, signs of a serious allergic reaction (swelling of the face or throat, difficulty breathing, rapid heartbeat), symptoms of dehydration from prolonged vomiting or diarrhoea, or any new or worsening low mood or thoughts of self-harm. The NHS medicines page for semaglutide lists the full urgent-care guidance in plain language and is worth bookmarking.

People with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2 should not use Wegovy at all, this is an absolute contraindication and is checked during the consultation.

Step 3: Groups for whom the Wegovy shot is not recommended

Wegovy is not licensed for people under 18, and it is not recommended during pregnancy, while breastfeeding, or when actively trying to conceive. Anyone in those situations should speak to their GP about alternative approaches to weight management. The MHRA advises using effective contraception while on treatment and for a wash-out period afterwards if pregnancy is being planned.

Women taking oral contraceptive pills alongside semaglutide should be aware that GLP-1 medicines can affect how quickly the stomach empties, which may reduce pill absorption. The NHS England guidance on weight-management injections recommends discussing contraception with your prescriber before starting. A non-oral backup method such as condoms is a sensible precaution during and shortly after dose changes.

If you are due to have surgery, tell your anaesthetist and surgical team that you take Wegovy. Delayed gastric emptying can affect anaesthetic risk, and your clinical team needs this information in advance.

Our detailed page on Wegovy's overall suitability covers these groups and the contraindication list in full. Questions about your specific situation are exactly what our prescribers are there for, and you can explore that through our free consultation.

Reporting side effects and where to get support

If you experience a side effect you are not sure about, the right first call is your prescriber. At nume, aftercare is available seven days a week precisely because side effects do not wait for office hours.

You can also report suspected side effects directly to the MHRA through the Yellow Card scheme. This is open to patients, not just clinicians, and the reports genuinely feed into post-approval safety monitoring. Wegovy's Black Triangle status means every report contributes to building the longer-term evidence base.

For broader context on what it's like to take semaglutide week to week, including the question of fatigue that many people raise, our page on semaglutide and tiredness is a good starting point. If you want a thorough rundown of what side effects the Wegovy shot can cause, from the mild and common to the rarer ones worth watching for, that page covers them in full. And if you're weighing up whether this treatment is the right fit overall, the Wegovy overview page covers the evidence, the eligibility criteria and how the private prescription route works.

Our prescribers go through side effects, contraindications and your medical history as a core part of every consultation, not as a box-tick. If you'd like a clear answer to the question of whether Wegovy is safe for most people to use, that page sets out the evidence and the key risk factors in plain terms. To explore whether Wegovy is suitable for you personally, start your free consultation and a GPhC-registered prescriber will review your answers the same day.