What Happens to Your Body in the First Month on Wegovy

Step 1: Week one, your first injection and the adjustment window

Most people give themselves their first Wegovy injection and feel broadly fine for the first day or two. Then, somewhere around day three or four, the gastrointestinal effects tend to arrive. Nausea is the one patients mention most often, sometimes alongside loose stools, burping or a heavy, full feeling after small amounts of food. This is your gut responding to semaglutide slowing gastric emptying, food is moving through you more slowly, which is part of how the medicine works.

It is completely understandable to feel anxious at this point, wondering whether every queasy hour means the treatment is wrong for you. For most people it isn't. The side effects in week one are usually at their sharpest and then begin to soften. Staying well hydrated, eating smaller portions and avoiding fatty or spicy food can take the edge off. The NHS semaglutide patient information page has practical guidance on managing these early effects.

Medically, week one is a holding pattern. Your dose is low enough that therapeutic weight-loss effects are minimal. The goal right now is simply tolerability. You can read more about what Wegovy is and how it works on our Wegovy treatment overview.

Step 2: Weeks two and three, appetite changes arrive before the scales move

This is the phase that tends to surprise people most. By the second or third week, many people notice they are stopping mid-meal because they feel genuinely full, not because they are trying to. Food noise (the background mental chatter about what to eat next) quietens. Some people describe it as the first time eating has felt uncomplicated.

And yet the scales may barely have shifted. That is not a sign the medicine is failing. Appetite suppression and early metabolic changes are happening before they register as measurable weight loss. Water retention, hormonal fluctuations and bowel habits all affect what you see on a given morning. Weighing once a week rather than daily tends to give a clearer picture.

If you are thinking about the cost of continuing beyond the first month, our Wegovy pricing page sets out what to expect transparently. Understanding the full picture early can help you plan.

Step 3: The four-week mark, what your prescriber looks at before your first dose increase

Around the four-week point, your prescriber will review how you have responded to the starter dose before deciding whether to move to 0.5mg. This is not a rubber-stamp step. They are looking at tolerability: were the side effects manageable? Are there any new health changes to factor in? Is there anything in your history that would favour staying at 0.25mg a little longer?

At nume, every review at this stage is carried out by a GPhC-registered Independent Prescriber, not an automated system. A real clinician reads your update before anything changes. This matters more than it might sound, because the titration schedule exists precisely to balance effectiveness against tolerability, and that balance is individual.

The STEP 1 trial, published in the New England Journal of Medicine, reported an average weight reduction of around 15% over 68 weeks at the 2.4mg maintenance dose. Month one sits at the very beginning of that curve, and if you are curious about the kinds of changes patients typically notice by the end of it, our page on what to expect from Wegovy after one month covers this in detail. If you are also weighing up whether to continue, our guide on stopping Wegovy after the first month explains what your options are and what your prescriber will consider. If you are curious how results tend to develop from here, our page on Wegovy after two months picks up the next stage of the journey.

When to contact your prescriber or seek medical help

Most of what happens in the first month is uncomfortable rather than dangerous. But there are signs that warrant prompt medical attention. Severe, persistent stomach pain that spreads to your back (with or without vomiting) can indicate acute pancreatitis, which the MHRA highlighted in a Drug Safety Update in January 2026 as an infrequent but serious risk with GLP-1 medicines. Signs of a serious allergic reaction, extreme dehydration from persistent vomiting or diarrhoea, and any thoughts of self-harm should all be taken seriously and assessed urgently.

For anything less acute, our prescribers offer priority aftercare seven days a week. If you have questions about what is and isn't normal in your first month, you can reach our clinical team directly. You can also find answers to common first-month questions on our FAQs page. And if you are already wondering how month one compares to what comes next, take a look at what patients typically notice by month three.

If you haven't yet started treatment and are weighing up whether Wegovy is right for you, check your eligibility with our prescribers, the consultation is free, and there's no obligation.