What happens when you take your first dose of semaglutide

Step 1: preparing for the injection, the practical bit people ask about most

A question our prescribers hear most weeks is simply: where exactly do I inject, and does it hurt? The three licensed sites are the abdomen (at least two inches from the navel), the upper thigh, and the outer upper arm. Most people find the abdomen easiest to reach. The needle on a Wegovy pen is short and fine, and injection discomfort is usually minimal, a brief sting at most. Let the pen come to room temperature for around ten minutes before you inject; cold medication from the fridge is one of the more common causes of irritation at the site.

Inject once, on the same day each week if you can, the day itself does not matter, only the consistency. You can take it with or without food. Swab the skin with an alcohol wipe, pinch gently, inject slowly, hold for a few seconds, then dispose of the needle safely. If you are building your injection routine, the Wegovy first dose guide on our site walks through the physical steps in more detail.

Never re-use a needle. If you are unsure about technique, your prescribing team can talk you through it; that is precisely what aftercare is for.

Step 2: the first few days, what is normal, what is not

The most common side effects in the early weeks are gastrointestinal: nausea, loose stools, burping, or a feeling of fullness that arrives faster than usual at meals. These tend to peak in the day or two after each injection and then ease. Fatigue and mild headache are also reported by some people in the first week. For the majority, symptoms settle within two to three weeks as the body adapts to the 0.25 mg level.

Eating smaller meals, avoiding very fatty or highly processed food, and staying well hydrated all help. If nausea is significant, having a light meal before the injection sometimes takes the edge off, though the formal advice is in your Patient Information Leaflet, and your prescriber is the right person to call if symptoms are disrupting daily life.

What is not normal: severe, persistent stomach pain that spreads to the back, with or without vomiting, warrants urgent medical attention. The MHRA's Drug Safety Update published in January 2026 highlights acute pancreatitis as an infrequent but serious risk with GLP-1 medicines, and the guidance is clear that this symptom needs same-day assessment. Signs of an allergic reaction (swelling of the face or throat, difficulty breathing) also need emergency care immediately.

Step 3: what the 0.25 mg dose is actually doing

Very little in terms of weight loss, and that is intentional. The first four weeks on semaglutide are about settling your system, not shifting the number on the scale. The 0.25 mg starting dose sits below the level at which most people notice a meaningful reduction in appetite. After four weeks, the prescriber typically moves you to 0.5 mg, then 1.0 mg, 1.7 mg, and eventually the standard maintenance dose of 2.4 mg, each step approximately four weeks apart, though the exact schedule is set by the clinician reviewing your progress.

The weight-loss evidence for semaglutide comes from the maintenance phase. In the STEP 1 trial, published in the New England Journal of Medicine, participants on 2.4 mg achieved an average of around 15% body-weight reduction over 68 weeks. That figure reflects sustained treatment, not the first pen. Understanding the full dose schedule before you start helps set realistic expectations; the semaglutide dosing overview covers each step in context. For those who want detail on what happens specifically in that first week, this page on the first-week dose goes deeper.

It is also worth knowing that 0.25 mg is not a licensed treatment dose for weight management, it is purely the tolerability entry point. Remaining at 0.25 mg indefinitely would not be clinically appropriate, and a prescriber would review your progress before any continuation or change. If you want to understand the higher dose steps, the Wegovy doses page outlines what each level is intended to achieve, including what to expect when you reach the semaglutide 2 mg dose on the way to maintenance.

Step 4: setting yourself up for the weeks ahead

Semaglutide is a prescription-only medicine, which means clinical oversight does not stop after the first pen. At nume (at nume) every repeat order is clinically reviewed before it is dispensed. If something is not right at 0.25 mg, that is the moment to flag it to your prescriber rather than pushing through to the next dose.

A few practical things that make the early weeks easier: keep a brief note of any side effects and when they occur relative to injection day, that pattern is useful information for your prescriber. Prioritise protein at meals, since appetite suppression can mean eating less overall, and muscle preservation matters during weight loss. Alcohol can worsen nausea in the early weeks, so some people find it worth reducing temporarily.

For the cost side of private semaglutide treatment, the Wegovy pricing page explains what a legitimate prescription typically includes and why the headline figure varies between providers. If you are still weighing up whether semaglutide or another licensed option is the right fit, the weight-loss treatment overview sets out the options clearly. When you are ready to talk to a prescriber, starting a free consultation is the next step, a real clinician reviews your answers the same day.