What to Expect When You Start Wegovy: a Week-by-Week Reality Check

The first injection: what the next 48 hours look like

Picture this: it's Tuesday evening, your Wegovy pen arrived that morning in plain packaging, and you've just done your first injection into the top of your thigh. For most people, the first 24 hours feel unremarkable. The 0.25mg starting dose is a tolerability dose — its job is to let your system get used to the medicine, not to trigger dramatic appetite suppression straight away.

By the following afternoon, some people notice a faint queasiness, a heavy feeling in the stomach, or simply less interest in finishing their evening meal. Others notice nothing at all for the first week. Both are normal. Fatigue is reported by some patients in those opening days, often in tandem with the nausea rather than separately. The NHS guidance on semaglutide confirms that these GI effects (nausea, diarrhoea, constipation, bloating) are the most common early reactions and tend to ease as the body adjusts.

A practical point worth raising early: your pen needs to be kept in the fridge, ideally somewhere you'll see it on the same day each week. A consistent injection day matters more than most people realise; keeping it next to something fixed in your routine (the condiments shelf, the milk) makes the weekly habit stick. If you want a fuller picture of the early weeks, our guide covering what to expect when starting Wegovy walks through the experience in detail.

The first pen covers four weekly doses at 0.25mg. That's a month of settling in before your prescriber typically moves you up.

Weeks five to twelve: when the appetite shift becomes real

By the time you reach 0.5mg and then 1mg, most people describe something genuinely different in how hunger feels. The clinical mechanism is specific: semaglutide is a GLP-1 receptor agonist, it mimics a gut hormone involved in appetite signalling and slows gastric emptying, meaning food stays in the stomach longer and the sensation of fullness arrives sooner and lasts longer. The effect isn't a sudden switch. It builds gradually over this middle phase.

For many patients, week five is the first time the change feels noticeable in everyday life, which is why a closer look at week five specifically can be useful if you're trying to gauge whether the medicine is working for you. Reduced appetite, earlier satiety, and less preoccupation with food between meals are the hallmarks of this phase. Weight loss typically follows appetite change, not the other way around.

Side effects in this period are worth watching honestly. Most GI symptoms settle within a few days of each dose increase and are milder than they were at the very start. If they don't settle, or if you develop severe stomach pain that radiates to your back, that requires urgent medical attention, the MHRA highlighted acute pancreatitis as an infrequent but serious known risk in its January 2026 Drug Safety Update for GLP-1 medicines. If you're uncertain about a symptom, contact your prescriber or call 111. Suspected side effects can be reported at the MHRA's Yellow Card scheme.

It's also in this phase that some people find nausea has largely gone but that food preferences have shifted. Very rich or very fatty meals become less appealing. Alcohol often feels stronger. These are expected effects, not problems. Our dedicated guide on what to expect with Wegovy covers these changes across the full course of treatment if you'd like more context.

The maintenance phase: managing expectations around results

The licensed maintenance dose for Wegovy is 2.4mg weekly (with a higher 7.2mg dose now also approved for people with a BMI of 30 or above, subject to clinical assessment). Most patients reach 2.4mg at around the five-month mark, having moved through 0.25mg, 0.5mg, 1mg and 1.7mg in roughly four-week steps. After that, the focus shifts from toleration to sustained weight management.

The STEP 1 trial (68 weeks, semaglutide 2.4mg versus placebo alongside lifestyle changes) reported an average weight reduction of around 15% at the 2.4mg dose. That is an average across thousands of participants; some people lose more, some less. Progress is rarely linear. Weeks can pass with little change on the scales while body composition continues to shift. How quickly Wegovy works depends on individual metabolism, baseline weight, dietary habits and adherence, and a prescriber is better placed than any average to interpret your pattern.

At this stage, protein intake, hydration and physical activity matter more than they did before. Appetite suppression can reduce overall food volume to a point where protein adequacy becomes a real consideration; your prescriber or a dietitian can help you plan for this. Anyone thinking about the cost implications of staying on treatment over the longer term will find the context on Wegovy pricing in the UK a useful reference.

If you are approaching the six-month mark and have seen less than 5% weight loss at your highest tolerated dose, your prescriber will review whether continuing makes sense, that review is a normal part of clinical care, not a failure. What happens when you stop Wegovy is a separate question worth understanding before you reach that point.

Starting treatment with a clinically regulated service means every dose step is reviewed by a real prescriber, not processed automatically. At nume, a GPhC-registered Independent Prescriber reviews your case before each stage of treatment. If you're ready to find out whether Wegovy is clinically suitable for you, start your free consultation and have your questions answered the same day.