Reading the Wegovy leaflet before your first injection

You've just picked up your first Wegovy pen (here's where to start

Picture this: the DPD parcel arrives in plain packaging, you open it at the kitchen counter, and there are two things inside) the pen and a folded paper about the size of a broadsheet page. That paper is the patient information leaflet. A lot of people fold it straight back and reach for the pen. That's understandable, but the leaflet is genuinely worth ten minutes of your time before the first injection.

The leaflet is split into clearly numbered sections: what Wegovy is and what it's used for; what you need to know before using it; how to use it; possible side effects; storage; and the contents of the pack. The full Wegovy patient information leaflet is also available online if you want to read it before your treatment arrives or want a searchable version. Section three, which covers how to use the pen, includes a step-by-step illustrated injection guide, injection site rotation, needle attachment, how to confirm a dose has delivered, and what to do if you miss a dose. None of those steps should be improvised; they are exactly as Novo Nordisk designed the device to be used, and the diagrams are clearer than most written descriptions.

The licensing information in the leaflet is also useful background. Wegovy is licensed for adults with a body mass index of 30 or above, or from 27 with at least one weight-related health condition, used alongside a reduced-calorie diet and increased physical activity. That context matters because the leaflet was written for the licensed population, if you have any condition not mentioned in your consultation, raise it with your prescriber rather than relying solely on the leaflet to guide you.

Side effects the leaflet describes, and which ones need urgent action

The side effects section is the part most people skip to first, and it is worth reading carefully rather than scanning the list and feeling alarmed. The semaglutide overview on our site summarises the same information, but the leaflet gives it in the full regulatory context, including frequency classifications (very common, common, uncommon and so on) drawn from the clinical trial data.

Very common side effects (meaning they affected more than one in ten people in trials) are dominated by gastrointestinal effects: nausea, diarrhoea, vomiting, constipation, stomach pain and burping. These were the findings reported in the STEP 1 trial published in the New England Journal of Medicine, and the leaflet reflects that evidence base directly. For most people these effects are most noticeable in the first few weeks or after a dose increase, and they settle as the body adjusts. Staying hydrated and eating smaller meals helps.

The leaflet also lists signs that require stopping treatment and getting medical help without delay. Severe, persistent stomach pain that radiates toward the back (with or without vomiting) is one of them, because it can be a sign of pancreatitis. The MHRA reinforced this in a Drug Safety Update in January 2026, which is why the leaflet language on this point is unambiguous. Allergic reactions (swelling of the face, lips or throat, difficulty breathing), gallbladder symptoms, and signs of severe dehydration are also listed as urgent situations. The leaflet is not trying to frighten you; it is telling you the difference between the normal, expected adjustment period and the rarer events that need a clinician's eyes on them quickly.

Storage, handling and the details that catch people out

The storage section of the Wegovy leaflet is short but specific, and getting it wrong can mean a wasted pen. Wegovy pens must be kept in the fridge at 2–8°C. The leaflet states a maximum time the pen may be kept at room temperature, always read the leaflet for that exact window rather than relying on second-hand guidance, because the figure applies to an unopened pen in a specific temperature range and the conditions matter. If you're wondering whether a pen that's been out of the fridge is still usable, the guide on whether to let Wegovy warm up addresses that question directly.

The leaflet also covers disposal: used needles go into a sharps container, not the household bin. It explains that pens are single-patient use only and must not be shared, even if the needle is changed. And it tells you what to do if you miss a dose, the rule is time-dependent, so read it rather than guessing.

One practical note the leaflet does not cover is how long semaglutide stays in your system after you stop, that's relevant if you're planning surgery or considering pregnancy. Our page on how long Wegovy stays in your system covers that in detail, but always discuss timing with your prescriber rather than acting on general guidance alone.

For anyone comparing injectable semaglutide with other treatment options, the weight-loss treatment overview sets out what's currently licensed in the UK. If you'd like to understand the cost side of Wegovy privately, the relevant context is on the how to get Wegovy page, which covers what a legitimate private prescription route looks like and what to expect from the process.

The NHS also publishes its own semaglutide guidance at nhs.uk/medicines/semaglutide, which is a plain-English complement to the full leaflet and a good cross-reference if a specific term in the leaflet needs clarifying.

If you've read the leaflet and you're ready to explore whether Wegovy is clinically appropriate for you, our prescribers review every consultation the same day. Start your free consultation and a GPhC-registered prescriber (a real clinician, not an automated system) will assess your suitability and answer any questions the leaflet didn't cover.