What actually happens in your first week on Wegovy

What the 0.25mg starting dose is actually doing

Wegovy's dosing ladder begins at 0.25mg weekly for a reason that has nothing to do with weight loss. At this concentration, semaglutide is settling into GLP-1 receptors involved in appetite signalling and gastric emptying, while your gut adapts to a slower rate of digestion. The prescriber-set titration schedule (rising through 0.5mg, 1.0mg and 1.7mg before reaching the 2.4mg maintenance dose) exists precisely because GI side effects are dose-dependent: starting low keeps them manageable. Think of week one as calibration, not treatment in the full sense.

For most people the physical experience in these early days is subtle. You might notice food feels more filling than usual, or that an afternoon snack you'd normally reach for simply doesn't appeal. That reduced drive to eat is the medicine working as intended. What you are unlikely to notice is the number on the scales moving dramatically, and that is normal. The week-by-week Wegovy progression explains how the picture changes as the dose rises.

Keep your pen in the fridge door where you'll see it on injection day; the SmPC specifies refrigerated storage at 2–8°C, and once you've connected a needle it should be used promptly. Small habits in week one tend to stick.

Side effects that commonly arrive in the first seven days

Nausea is the most reported first-week experience. It tends to arrive a few hours after the injection and, for many people, eases within a day or two as the body adjusts. Constipation, loose stools, mild indigestion and a general feeling of fullness are also common early on. The NHS semaglutide medicines page lists the full side-effect profile and is a practical first reference if you're unsure whether what you're feeling is expected.

A few practical adjustments help. Eating smaller portions, avoiding high-fat meals on injection day, and staying well hydrated all reduce the sharpness of GI symptoms. Symptoms that are severe, that prevent you keeping fluids down, or that include intense stomach pain radiating to the back should be assessed urgently, the latter can be a sign of pancreatitis, which, while uncommon, requires prompt medical attention. Report anything unexpected to your prescriber and, if you suspect a side effect, to the MHRA Yellow Card scheme.

Fatigue and mild headache occasionally appear in the first week too, often linked to eating less and drinking less than usual. Most people find both settle naturally as new routines form around the medicine.

What to realistically expect from the scales, and when to look

Clinical trial data makes this straightforward: meaningful weight reduction in the STEP programme accumulated over months, not days. Week one at 0.25mg is not the point at which semaglutide's full pharmacological effect is active. Some people lose a small amount of water weight in the first days, partly from eating less; others see no change at all. Both are normal, and neither tells you much about how treatment will go long-term.

The more useful thing to track in week one is tolerance. Did the injection go smoothly? Did side effects stay manageable? Are you eating a little less without feeling deprived? A positive answer to those questions is the real marker of a good start. The trajectory of results over the following weeks and months is covered on the Wegovy treatment overview page, and how things typically look by week five gives a more concrete sense of the timeline.

If you're considering starting and want to understand the full cost picture before committing, the Wegovy pricing guide sets out what to look for in a transparent private prescription service.

When to contact your prescriber, and how clinical oversight continues

A question our prescribers hear regularly is: who do I call if something doesn't feel right? The answer matters in week one, when most people are new to the medicine. Side effects that are severe, persistent or worrying (significant vomiting, signs of dehydration, an allergic reaction, or anything unexpected) should prompt direct contact with your prescriber or, in an urgent situation, NHS 111 or A&E. You can also read about what Wegovy results look like for real patients to get a clearer sense of what the treatment journey involves.

At nume, clinical oversight doesn't stop at the first prescription. A GPhC-registered prescriber personally reviews each patient before every repeat supply, checking that treatment is still appropriate and that any concerns are addressed. That review is carried out by a real clinician, not automated software. Many patients find it helpful to understand what to expect when they reach week six of Wegovy, as that milestone often marks a meaningful shift in how treatment feels. You can read more about how our clinical team approaches ongoing care on the clinical team page, or see common questions covered on the FAQs page. If you'd like to begin that process, the first step is a free consultation through our weight-loss treatments page.