When to take your first dose of Wegovy: what to expect

The pen is in your hand, what does 'first dose' actually mean?

You've just received your first Wegovy pen. It has been sitting in the fridge at 2–8°C, as the Patient Information Leaflet instructs. The question most people ask at this point isn't really about the medicine, it's about the practical reality of the moment: do I do this tonight, or wait until the weekend? Morning or evening? Does it matter?

The honest answer is that the timing within the day matters far less than consistency across the weeks. Wegovy's once-weekly dosing schedule means you need to choose a day you can reliably return to. Many people pick a day when they're at home (a Sunday evening, or a Saturday morning) so any early side effects from that first injection settle before a working week begins. That logic is sensible, though not a clinical requirement. If a Tuesday lunchtime is what you'll remember, that works just as well.

One thing worth setting straight early: a common belief is that you should inject on an empty stomach, as if timing around meals matters the way it does for some oral medicines. With Wegovy's subcutaneous injection, food timing is not a factor. You can inject after dinner, before breakfast, or mid-afternoon, and the effect on how the medicine is absorbed is the same. The injection goes under the skin of your abdomen, thigh or upper arm; the stomach contents at that moment are irrelevant. If you want to learn more about how semaglutide doses are structured across the full treatment course, our guide to the Wegovy dose schedule sets it out clearly.

Why 0.25 mg and not the dose that produces weight loss?

The 0.25 mg starting dose is a tolerability measure. Semaglutide works partly by slowing how quickly food leaves the stomach, which is why nausea is the most commonly reported early side effect. Beginning at the lowest available dose gives your digestive system time to adjust before the dose increases. It is not the dose at which most people see meaningful weight reduction, that becomes relevant at the higher maintenance doses, reached over several months of careful titration. Thinking of 0.25 mg as the therapeutic payload leads to disappointment; thinking of it as the system settling in tends to help people stay the course.

The standard titration pathway begins at 0.25 mg and moves upward (0.5 mg, then 1.0 mg, 1.7 mg and eventually 2.4 mg) with roughly four weeks at each level, guided by your prescriber. If you are unsure how many mg of Wegovy you should be taking at any point in that process, our dedicated page walks through each step in detail. The STEP 1 trial, published in the New England Journal of Medicine, found an average body-weight reduction of around 15% over 68 weeks at the 2.4 mg maintenance dose. That outcome is the cumulative result of sustained treatment, not the first pen. Questions about when to step up are a clinical conversation, our page on when to increase your Wegovy dose covers the principles, though the decision always belongs to your prescriber.

What to watch for in the days after your first injection

Most people find the first week unremarkable. Some notice mild nausea, a reduced appetite, or a little tiredness in the day or two following the injection, all of which fit the expected profile of semaglutide at 0.25 mg. These sensations, where they appear, tend to be lighter after the first dose than at later, higher doses.

A few practical points for those early days. Stay well hydrated, GI side effects, even mild ones, are more uncomfortable when you're not drinking enough water. Eat regular, reasonably sized meals rather than skipping food, which can make nausea feel worse. If you experience severe or persistent stomach pain, particularly pain that spreads to your back, seek medical advice promptly; MHRA Drug Safety Updates identify acute pancreatitis as an infrequent but serious side effect of GLP-1 medicines that warrants urgent attention.

If you are a woman using oral contraceptives and switching to Wegovy for the first time, note that no equivalent concern about pill absorption has been identified with semaglutide in the way it has with tirzepatide. Your prescriber can advise based on your full medication history. The same applies to any other regular medicines, bring a full list to your consultation. For a broader sense of how this medicine fits into private weight-loss treatment in the UK, the weight-loss treatment overview is a useful starting point.

Recording your injection day and building the habit

Regularity is the single most practical factor in those first weeks. Set a recurring reminder on your phone. Note the day in a journal if that helps. The reason this matters is straightforward: semaglutide's mechanism depends on a steady, once-weekly rhythm. Taking a dose a day early or late occasionally is unlikely to cause harm, but erratic timing makes it harder to track how your body is responding and complicates any prescriber review of your progress. Understanding when you should increase your Wegovy dose is also easier when you have a consistent record to look back on.

Keep a simple note of each injection, date, injection site, and any symptoms you notice. This is the kind of record that makes a follow-up conversation with a clinician genuinely useful, rather than a rough reconstruction from memory. If you have questions before your first dose or want to review the full dose options available, the dosage guidance page and the Wegovy treatment information page are worth reading alongside your Patient Information Leaflet. Our prescribers are also available through the contact page if a question comes up between reviews. When you're ready to discuss whether Wegovy is appropriate for your situation, you can start your free consultation with the nume team, a GPhC-registered prescriber, not an algorithm, reviews every submission the same day.