How to Use Wegovy for the First Time: a Step-by-Step Guide

What the official guidance says about starting Wegovy

The NHS semaglutide guidance and Wegovy's Summary of Product Characteristics both confirm that treatment opens at 0.25 mg once weekly. That starting dose is not where the weight-management effect sits, it exists to let your digestive system settle before dose increases begin, typically at roughly four-week intervals, at your prescriber's direction. Clinical trial data from the STEP 1 study, published in the New England Journal of Medicine, involved weekly semaglutide 2.4 mg over 68 weeks and recorded an average body-weight reduction of around 15%, but that endpoint was reached after a structured titration starting exactly where yours will: 0.25 mg. Knowing that context helps first-time users resist the urge to rush. If you want a full walkthrough before you begin, our guide on how to take Wegovy for the first time covers every step from preparation through to aftercare. Your pen is pre-set at the prescribed dose; there is no dial to adjust and nothing to measure.

Keep the pen in the fridge (2–8°C) until you need it. Take it out roughly 30 minutes beforehand so it reaches room temperature, a cold injection is noticeably less comfortable. Check the liquid in the window: it should be clear and colourless. If it looks cloudy, has visible particles or has been frozen, do not use it; contact your prescriber or our support team for guidance.

The injection itself: site selection, preparation and technique

Wash your hands thoroughly first. Pick one of the three licensed sites (abdomen, front thigh, upper arm) and clean the area with an alcohol swab; let the skin dry completely before you inject, because wet skin can sting. Remove the cap from the pen, place the flat end firmly against the skin (no need to pinch), and press the button until you hear a click. Then count to six (a full six seconds) before lifting the pen away. That pause allows the full dose to be delivered; lifting early is the mistake our prescribers hear about most often from first-time users.

A small amount of liquid remaining in the pen window after injection is normal and does not mean the dose was incomplete. Note where you injected this week, because you should rotate sites to avoid skin changes over time. The used pen goes straight into a sharps container, not the household bin. If you are handling the device for the very first time, our dedicated page on getting your Wegovy pen ready for first use explains how to attach the needle and prime correctly before you start. If you are doing your first injection on a weekday morning before a busy day, the 12pm cut-off matters less for the injection timing itself than for practical things like having 30 minutes for the pen to warm up before you need to leave the house.

Side effects that commonly appear after the first dose

Gastrointestinal effects (nausea, constipation, loose stools, an uncomfortable fullness) are the most reported early reactions. They tend to peak in the first day or two after each injection and settle as the body adapts. Eating smaller portions and avoiding high-fat or spicy food around injection day helps many people. Staying well hydrated matters, particularly if nausea is reducing how much you want to drink.

Most first-time users find the GI effects manageable. Serious reactions are uncommon but worth knowing: severe, persistent stomach pain that radiates to the back (potentially a sign of pancreatitis) warrants urgent medical assessment. The MHRA's January 2026 Drug Safety Update highlighted acute pancreatitis as an infrequent but serious consideration for GLP-1 medicines; if this symptom appears, stop the injection and seek help promptly. You can report any suspected side effect directly at the MHRA Yellow Card scheme. Mild injection-site redness or itching usually resolves within a day.

What happens after your first injection

Your next dose is due seven days later, on the same day of the week. If you miss your window by up to five days, take it as soon as you remember, then resume your usual schedule. Beyond five days late, skip it and wait for your next scheduled day, your Patient Information Leaflet and prescriber are the definitive reference for missed-dose decisions, not general guidance you find online.

You can learn more about storing your Wegovy pen correctly after first use, including the room-temperature window once the pen has been opened. If the mechanism feels stiff or the pen does not fire as expected, the troubleshooting guide for a stuck Wegovy pen covers the most common causes. For a fuller picture of how Wegovy works and what to expect over the course of treatment, our Wegovy treatment overview brings together the clinical background and practical detail in one place. If you are still deciding whether Wegovy is right for you, or want to understand cost before committing, our Wegovy cost guide explains what a private prescription typically includes. When you are ready to find out whether you are clinically eligible, you can check your eligibility with our prescribers at no charge.