What to do before taking Wegovy: preparing yourself properly

You've got your prescription, here's what the next 48 hours actually look like

Your pen arrives in plain packaging, tracked by DPD, and the first instinct for most people is to start immediately. Slow down for a moment. Before your first injection there are a handful of things worth doing, and doing in order.

First, read the Patient Information Leaflet inside the box. The Wegovy SmPC on the eMC contains the definitive storage and handling instructions, but the in-box leaflet is written for patients and covers the specific details you need: the room-temperature window if your fridge is temporarily unavailable, what a bent or blocked needle looks like, and when not to inject. These are not abstract warnings. The storage window in particular is a short one, and it matters.

Second, check your fridge. Wegovy pens are kept at 2–8°C. Not in the freezer, not in the door where the temperature fluctuates most. A pen that's been frozen or left at room temperature beyond the window described in the leaflet should not be used. It sounds basic. A question our prescribers hear most weeks is whether a pen that sat out overnight is still usable, the answer depends on the exact window and the manufacturer's guidance, so the leaflet is the right place to check, not a forum.

Third, plan your first injection day. Many people choose a day when they can take things gently if nausea hits. The timing of your injection relative to your routine can make a real difference to how you feel in the hours that follow. There's no universally correct time, but if you want a full rundown of what to do before starting Wegovy, reading through that guidance before the day itself means you're not making decisions under pressure.

Medicines, contraception and other things to raise with your prescriber first

Wegovy slows gastric emptying, which affects how quickly other medicines are absorbed. For most people this isn't a significant problem, but it's worth mentioning any regular medications when you complete your consultation, not because the combination is automatically unsafe, but because your prescriber needs the full picture.

Contraception deserves specific attention. For women taking Wegovy (semaglutide), the NHS notes there isn't currently the same evidence of reduced oral contraceptive absorption as there is for tirzepatide. That said, the guidance on NHS England's weight-management injections page recommends discussing contraception with your healthcare team before starting any weight-management injection, so raise it, even if the answer turns out to be that no change is needed.

Pregnancy, breastfeeding and trying to conceive are all contraindications. Wegovy is not used in these situations. Under-18s are not a licensed population either. If any of these apply, the conversation to have is with your GP, not a self-managed dose.

Some conditions prompt extra caution: a personal or family history of medullary thyroid carcinoma, MEN2, or previous pancreatitis all require a prescriber discussion before starting. These are picked up at the consultation stage through our clinical assessment process, but being prepared to answer questions about your medical history makes that review faster and safer for you.

Eating and drinking before your first dose matters more than people expect

Nausea is the most commonly reported side effect in the early weeks, and it's not random. What you eat in the 24 hours before and after your first injection has a measurable effect on how bad it gets. The pattern that tends to work: small meals, low in fat, modest portions, nothing heavy in the two hours before injecting.

Alcohol is worth cutting back before you start. It interacts poorly with the nausea profile and adds empty calories at exactly the point your appetite is adjusting. Keeping hydrated is straightforward but important, semaglutide can cause vomiting and diarrhoea in some people, and dehydration compounds both.

You'll also find it useful to know what Wegovy is actually trying to do to your appetite. Understanding the mechanism (it mimics a hormone that signals fullness to your brain and slows the rate at which your stomach empties) helps explain why eating to old portion sizes feels actively uncomfortable on treatment. Reading about how semaglutide works in practice before your first dose means the experience makes sense as it happens, rather than feeling alarming.

The broader picture of what life on Wegovy looks like (not just day one) is worth reviewing too. The ongoing habits that support treatment are different from the immediate pre-start checklist, but reading ahead gives you a realistic sense of what you're committing to.

A note on expectations before you inject for the first time

STEP 1 (the pivotal 68-week clinical trial of semaglutide 2.4mg) reported an average weight reduction of around 15% in participants without diabetes, alongside lifestyle changes. That's a meaningful result. It's also an average across thousands of people, and it took over a year to achieve. Starting Wegovy is starting a long process, not triggering a rapid event.

The starting dose of 0.25mg is low by design. Its job is to let your body adjust to the medicine, not to produce weight loss from week one. Some people feel frustrated by that. Knowing it in advance helps. The prescriber decides the titration schedule (when and whether to increase) based on how you're tolerating each dose, so keep notes on how you're feeling and flag anything unusual.

People often find it useful to read accounts of what others wish they'd known before starting. The things patients commonly say they'd have done differently include several that overlap with this page, but also some that only become clear after the first few weeks. Worth a read before dose one.

If you're still working out whether Wegovy or another licensed weight-loss medicine is the right fit (or how private prescribing compares on cost) those are questions to bring to a consultation rather than answer alone. When you're ready, speak to our prescribers through a free consultation and get a clinical view on your specific situation.