What happens with your semaglutide first week dose?

Why does semaglutide treatment start at such a low dose?

A question our prescribers hear most weeks: "Is 0.25mg actually doing anything?" The honest answer is: yes, but not in the way most people expect. The 0.25mg dose activates GLP-1 receptors in the gut and brain, slowing how quickly the stomach empties and beginning to dampen appetite signals. The physiological changes are real. What the starter dose is deliberately not calibrated to do is produce the sustained appetite suppression associated with the maintenance doses used in clinical trials.

The reason for beginning here comes down to tolerability. GLP-1 receptor agonists produce gastrointestinal effects (nausea above all) that are most pronounced when the dose climbs quickly. Starting at 0.25mg for four weeks lets the body habituate gradually, so that when the dose increases, the side-effect burden is typically much lower than it would be at a cold start on a higher dose. The full semaglutide dosing pathway maps out how this escalation works at each stage.

The prescribing schedule that underpins this approach is described in the Wegovy Summary of Product Characteristics on the Electronic Medicines Compendium (eMC), which is the reference document for licensed UK prescribing. Any specific questions about your own titration schedule belong with your prescriber, not the leaflet alone.

What do people actually feel during the first week?

Week one is rarely dramatic. Some people notice a modest reduction in appetite, food feels less compelling, portions feel satisfying sooner. Others notice nothing at all beyond a slight tenderness at the injection site. Both responses are normal at 0.25mg.

The side effects worth knowing about are almost all gastrointestinal: nausea is the most frequently reported, followed by loose stools, constipation in some people, burping and a general sense of fullness that arrives earlier than usual at meals. Fatigue and mild headache appear in a smaller proportion of users in the first fortnight. These effects tend to be mild to moderate and settle as the body adjusts, typically within the first one to two weeks at each dose level. People sometimes also wonder whether Wegovy has any effect on liver enzymes, which is a reasonable question to look into alongside the standard side-effect profile. The NHS semaglutide medicines page sets out the full side-effect profile with guidance on when to seek medical advice.

One practical note: injecting into the abdomen, thigh or upper arm on a rotating basis each week reduces injection-site reactions. The exact instructions for administration are in the patient information leaflet that comes with your pen. If you have questions about side effects you are experiencing, our support team is available seven days a week.

Anything more serious (severe stomach pain, signs of an allergic reaction, or symptoms that worry you) warrants prompt medical attention, not a wait-and-see approach.

How does the first-week dose fit into the broader schedule?

Semaglutide (Wegovy) follows a defined escalation: 0.25mg for the first four weeks, then 0.5mg, 1.0mg, 1.7mg, and finally 2.4mg as the licensed maintenance dose for weight management, with the prescriber assessing readiness at each step. A week-by-week breakdown of the semaglutide dose schedule covers each stage in more detail.

The MHRA has also approved a higher 7.2mg maintenance dose, announced in early 2026 as the next step for eligible adults who reach 2.4mg. Whether that pathway is appropriate depends entirely on clinical review. The evidence base for semaglutide at maintenance doses comes from the STEP 1 trial, published in the New England Journal of Medicine, which reported an average weight reduction of around 15% over 68 weeks at 2.4mg. Week one at 0.25mg is a long way from that outcome, but it is the necessary first step toward it.

Thinking about the cost of treatment at this stage is reasonable. The Wegovy price page explains how private treatment is structured and what the single transparent price at nume includes.

What should you do if week one feels difficult?

Most people find week one manageable. If nausea is noticeable, eating smaller meals, avoiding very fatty or rich food, and staying well hydrated all help. Cold or room-temperature food tends to be easier to tolerate than hot dishes for some people in the first days. Timing the injection for an evening might mean the peak of any nausea passes during sleep, though this is a practical choice, not a clinical instruction.

If symptoms feel unmanageable or you are unable to keep fluids down, contact a healthcare professional. Severe dehydration from persistent vomiting or diarrhoea can stress the kidneys and should not be pushed through. Your prescriber and aftercare team are the right people to talk to, not a forum.

At nume, every repeat order is reviewed by a GPhC-registered Independent Prescriber before dispatch. If the first weeks raise questions, that review is where they get answered properly. You can also read about what to expect from your first semaglutide dose more broadly, or explore the full range of weight-loss treatment options we offer before deciding on next steps. If you are ready to get started, speaking to our prescribers is the natural next step.