Wegovy starting dose: what happens in week one and why it matters

You've just been prescribed Wegovy, and your first pen feels almost too low to matter

It's a reaction our prescribers hear often. Someone has spent months reading about 15% weight loss in clinical trials, and then they're handed a 0.25 mg pen with instructions to inject it once and wait a week. That gap between expectation and reality can feel deflating.

Here's what the dose is actually doing. Wegovy is a GLP-1 receptor agonist: it slows how quickly food leaves your stomach and sends signals to the brain that reduce appetite. At 0.25 mg, those effects are present but mild. What the dose is really doing is training your gut to tolerate the medicine at all, starting high causes nausea in most people, so the stepped approach is built into the licence from the start. The full Wegovy dose schedule runs from this 0.25 mg opener through to 2.4 mg (and now up to 7.2 mg for some patients), but each rung earns the next.

You stay at 0.25 mg for four weeks. Then, assuming you're tolerating it reasonably well, the prescriber moves you to 0.5 mg. You can read more about what changes when you step up to 0.5 mg if that transition is what's on your mind right now.

The side effects are usually worst at the start, here's the honest picture

Nausea is the most commonly reported side effect of semaglutide, and it tends to peak in the first few days after an injection, particularly when the dose steps up. Other GI effects (loose stools, constipation, reflux, burping) appear in a meaningful proportion of people. Fatigue and mild headaches are also common early on. The good news is that these symptoms are usually mild to moderate and settle within days for most people, sometimes a little longer after a dose increase.

The NHS semaglutide medicines page lists the full side effect profile in plain language and is worth bookmarking. A few symptoms warrant prompt medical attention: severe, persistent stomach pain that radiates to the back can be a sign of pancreatitis, which the MHRA flagged in a safety update in January 2026 as an infrequent but serious risk with GLP-1 medicines. Don't sit on that symptom, contact a doctor the same day.

If side effects at 0.25 mg feel rough, tell your prescriber before moving to 0.5 mg. Staying at the starting dose a little longer is a recognised clinical option. You are not behind schedule if you do.

When does the starting dose actually start working?

Appetite suppression can begin even at 0.25 mg, some people notice they feel full sooner in the first week or two. But measurable weight change at the starting dose is modest. The STEP 1 trial, published in the New England Journal of Medicine, studied semaglutide 2.4 mg over 68 weeks and recorded an average body-weight reduction of around 15%; that result is built on reaching and sustaining the maintenance dose, not the opening weeks at 0.25 mg.

Think of the first month as groundwork. Practically, pick the same day each week for your injection (Monday morning before the school run, Saturday evening, whichever slot you'll actually stick to) because consistency matters more than which day you choose. Inject into the abdomen, thigh or upper arm, rotating sites each week.

For context on where semaglutide sits alongside other licensed options, the semaglutide starting dose page covers how the opening dose compares across different semaglutide presentations. And if you're curious about the newer higher-dose option that was approved by the MHRA in April 2026, the Wegovy 7.2 mg pen page explains what that approval means and who it's intended for.

Getting started privately: what the consultation involves

Wegovy is a prescription-only medicine. In the UK the only legal route to it is a clinical assessment by a registered prescriber, who confirms it is appropriate for you before any treatment begins. On the NHS, Wegovy is available through specialist weight management services under NICE's guidance (TA875), though waiting lists can be long and eligibility criteria are specific. Private treatment through a regulated online pharmacy removes the wait, subject to clinical suitability.

At nume, a GPhC-registered Independent Prescriber reviews your consultation personally, a real clinician reads your answers the same day, not a piece of software. Identity is verified, weight is confirmed on a live video call, and treatment is dispatched only once those checks are complete. The Wegovy cost page covers what the private price includes; one transparent fee covers the consultation, prescription, treatment and free next-working-day delivery. No subscription, no auto-renewal.

If you want to understand the full journey from 0.25 mg through to maintenance, the Wegovy overview is a useful place to read the broader picture. Or, if you're ready to see whether you meet the eligibility criteria for treatment, the free consultation takes a few minutes to complete.