What happens with your first semaglutide injection?

Is the first injection actually doing anything, or is it just a starter dose?

This is probably the most common question our prescribers hear in the early weeks, and the honest answer is: both things are true at once. The 0.25 mg starting dose of semaglutide is genuinely the lowest rung on the titration ladder, it exists because jumping straight to a therapeutic level would leave most people fighting significant nausea from day one. Your prescriber will typically hold you at this dose for four weeks before considering an increase, and the schedule continues from there at roughly four-week intervals.

Weight loss during the first month tends to be modest. That is not a sign the medicine is not working; it is the dose doing exactly what it was designed to do. Some people do notice their appetite shifting even at this stage, but the bigger effects build as the dose rises over subsequent months. The Wegovy overview page covers how the full titration schedule unfolds and what the trial evidence shows at maintenance doses.

One thing worth knowing: semaglutide is a GLP-1 receptor agonist, which means it works partly by slowing gastric emptying and signalling fullness to the brain. Those mechanisms begin at 0.25 mg, the appetite change is real, even if the scale does not move dramatically in week one. Patience with the first pen is, genuinely, part of the process. The guide to your first Wegovy injection walks through what the pen looks and feels like in practice.

Where do you inject, and does the technique really matter?

Yes, technique matters, not because getting it slightly wrong will harm you, but because doing it consistently well reduces the chance of injection-site reactions and makes the weekly routine easier to keep up. The three licensed sites are the abdomen (at least a couple of centimetres from the navel), the front or outer thigh, and the outer upper arm. Rotating between sites each week is not optional advice; staying in the same spot repeatedly can cause localised lumps under the skin.

The Wegovy pen is pre-filled and pre-set to the correct dose, so there is no drawing up or dialling. Before your first use, read through the Patient Information Leaflet carefully, it contains the exact steps for removing the cap, checking the solution and pressing the injector. Cleaning the skin beforehand with an alcohol swab is standard practice. Inject at a 90-degree angle, press firmly, and hold for the count specified in the leaflet to ensure the full dose is delivered.

The pen should be stored in the fridge (2–8°C) until you need it. If it has been out of the fridge, refer to the Patient Information Leaflet for the exact window, that figure varies and is the definitive source, not any third-party estimate. For a step-by-step walkthrough of the physical process, this guide covers the pen's first use in detail.

What side effects are most likely after the first dose?

Gastrointestinal effects are the most commonly reported, particularly in the early weeks: nausea, loose stools, constipation, indigestion and burping. Fatigue and mild headache are less common but do occur. For most people these effects are mild to moderate and ease within a week or two as the body adjusts, they are also why the starting dose exists in the first place. Eating smaller, lower-fat meals and staying well hydrated tends to help.

A small number of people experience more persistent or severe symptoms. The NHS semaglutide medicines page lists the full side-effect profile and explains which symptoms need prompt medical attention. The one that is worth knowing before you start: severe, persistent stomach pain (especially if it radiates to the back) should be assessed medically the same day. Pancreatitis is a rare but serious risk with GLP-1 medicines and the MHRA has issued specific guidance on recognising it early; you can report any suspected side effect via the Yellow Card scheme.

Injection-site reactions (redness, itching, a small lump) are another possibility, particularly if you use the same site repeatedly. Rotating correctly, as above, is the most effective prevention. If a reaction does not settle within a few days, mention it to your prescribing team.

What does ongoing clinical support look like after the first injection?

Starting semaglutide is not a one-off transaction. Dose changes happen approximately every four weeks, each of which warrants a clinical review rather than an automatic step-up, your response and tolerability both matter. Good aftercare means someone is available when a side effect catches you off guard at 8pm on a Saturday, not just during a GP's office hours.

For people considering the private route, it is worth understanding what a service's support actually covers before you commit. Understanding Wegovy's costs in the UK explains what a transparent all-in price should include (consultation, prescription, delivery and ongoing clinical review) because a headline figure that strips those out can look cheaper and leave you without support when you need it. At nume, every repeat order goes back in front of a prescriber; nothing auto-renews.

Wegovy is a prescription-only medicine, and the legal route to it is a clinical assessment by a GPhC-registered prescriber. If you have questions about whether semaglutide is the right fit for your situation, our team is available seven days a week. More on what semaglutide injections involve may help if you are still weighing your options.