How Wegovy works across a week — and what to expect each day

What the drug is actually doing during those seven days

Semaglutide is engineered to last. Its molecular structure binds to albumin in the blood, stretching its half-life to roughly seven days, which is exactly why a once-weekly injection is enough. After you inject, levels climb over the first 24–48 hours and then hold relatively steady rather than spiking and crashing. This sustained exposure is the mechanism behind the consistent appetite reduction that the clinical weight-loss evidence for Wegovy points to.

At the receptor level, semaglutide activates GLP-1 pathways in both the gut and the brain, a process worth understanding in detail before you begin treatment. In the gut it slows gastric emptying, so food sits with you longer and fullness signals arrive sooner. In the hypothalamus it dials down hunger hormones and reinforces satiety signals. Neither effect is binary, they ramp up over the first week or two of treatment and build further as the dose is titrated upward. If you are curious about how Wegovy works at a biological level, reading through that before you start can make the early side effects much less alarming.

One practical point: the injection itself is subcutaneous, meaning just beneath the skin of the abdomen, thigh, or upper arm. You rotate sites each week. The NHS medicines page for semaglutide covers injection technique, storage and what to do if you miss a dose, always the right place to start for the practical detail, alongside your Patient Information Leaflet.

The day-by-day experience most people describe

Broadly, the week splits into three phases, though every person's pattern is different and the prescriber who reviews your case will know your history better than any general description can.

Days one and two tend to be the roughest. Drug levels are rising and the gut is adjusting. Nausea is the most frequently reported side effect, sometimes accompanied by a feeling of fullness even after small meals, burping, or a general queasiness that makes rich or fatty food unappealing. Most people find this settles by day three or four. Eating smaller portions, staying well hydrated, and keeping meals lower in fat during those first two days makes a real difference for many people, a question our prescribers hear regularly.

Mid-week, days three to five, is typically when Wegovy feels most comfortable. Levels are steady, appetite suppression is in full effect, and the GI symptoms have usually eased. This is the stretch where people tend to notice they simply stop feeling hungry at their usual meal times.

By days six and seven (particularly before the next dose) some people notice appetite beginning to creep back. This is normal. It reflects the gradual decline in semaglutide levels as the week closes out. Injecting on a consistent day, rather than letting the interval drift to eight or nine days, keeps that end-of-week dip as shallow as possible. If you want a broader picture of when the effects of Wegovy begin, early weeks look rather different from steady-state treatment.

Deciding whether this weekly pattern suits you, and what the evidence says about results

The decision to start Wegovy is partly a clinical one (eligibility, contraindications, other medicines you take) and partly a practical one about whether a weekly injectable fits your routine. On the practical side, the pen arrives by tracked DPD delivery in plain, unbranded packaging (there is no visible indication of what is inside) and it lives in the fridge door between uses.

On the clinical side, NICE's appraisal of semaglutide for weight management (TA875) sets out who qualifies under NHS criteria, which are stricter than the licensed criteria for private treatment. 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 2.4mg maintenance dose, a figure that builds over many months, not days. How well Wegovy performs for weight loss covers the full trial picture, including what influences individual results.

The weekly rhythm described above is just the start. Titration moves the dose upward over several months under prescriber supervision, and the response (both in terms of results and tolerability) shifts at each stage. If cost context is relevant to your decision, what to expect when getting Wegovy through a UK pharmacy covers pricing structure and what a legitimate private prescription should include.

If you have questions about how this fits your health picture, our prescribers review consultations personally (not via automated screening) and can talk through your specific situation. Start your free consultation to see whether Wegovy is clinically appropriate for you.