How a Wegovy pen works: a step-by-step practical guide

Step 1: prepare, check, clean, choose your site

Before anything else, take the pen from the fridge and let it sit at room temperature for about 30 minutes. Cold semaglutide can sting more on injection. While you wait, do a quick visual check: hold the pen up to the light and look through the inspection window. The liquid should be clear or slightly yellow and free of visible particles. If it looks cloudy, discoloured or contains floating matter, do not use it, contact your prescriber or pharmacist. That 30-second habit catches a surprising number of storage or transit issues before they become a problem.

Clean the chosen injection site with an alcohol swab and let it dry completely, wet skin can introduce minor irritation. Abdomen (at least 5 cm from the navel), outer thigh and upper arm are all licensed sites; rotate each week to avoid localised tissue changes. Alcohol swabs designed for injection-site prep are available if you need to restock. Remove the pen cap only when you're ready to inject.

The mechanism behind Wegovy injections (why semaglutide is given subcutaneously rather than orally in its injection form) is worth understanding if you're new to this route of administration.

Step 2: inject, press, hold, listen for the click

Place the pen firmly and flat against the cleaned skin. You don't need to pinch the skin unless your prescriber has advised it for your particular site. Press the injection button fully and hold the pen in place. The device drives the needle in, delivers the dose and retracts, all in one motion. Most people describe it as a faint pressure rather than a sharp sensation.

Hold for a slow count of ten before removing the pen. This pause matters: lifting the pen too quickly can draw semaglutide back out before the full dose has dispersed into the tissue, which is exactly the kind of thing described on our page about liquid appearing after a Wegovy injection. A small dot of blood or a tiny bruise at the site is normal and not a sign of error.

For a sense of how the medicine starts working after the injection is given, the timeline for Wegovy's effects explains what to expect in the hours and days that follow, including why appetite changes are often gradual rather than immediate.

Step 3: after the injection, disposal and what to watch for

Once the pen has clicked and locked, it's spent. The needle is automatically covered, you won't re-expose it. Place the used pen in a sharps container rather than the household bin; local pharmacies accept these for safe disposal. Do not attempt to remove or recap the needle.

Common side effects in the days after injection are mostly gastrointestinal: nausea, loose stools, constipation, reflux or belching. These tend to be most noticeable early in treatment or after a dose step-up, and usually settle within a week or two as your system adjusts. Eating smaller, lower-fat meals and staying hydrated helps considerably. The NHS semaglutide patient information at nhs.uk/medicines/semaglutide lists the full side-effect profile clearly.

Seek medical help promptly for severe, persistent stomach pain that radiates toward the back, this can indicate pancreatitis, a known but infrequent risk the MHRA flagged in a 2026 Drug Safety Update for GLP-1 medicines. The MHRA Yellow Card service is the right place to report any suspected side effect, however minor it seems.

Dose steps and why the schedule exists

Treatment opens at 0.25 mg, a dose whose job is purely to let your body adjust, not to produce weight loss. Your prescriber then moves you up through 0.5 mg, 1.0 mg and 1.7 mg toward the 2.4 mg maintenance dose, spending roughly four weeks at each level. People who tolerate each step well tend to experience fewer side effects at the next. The 7.2 mg pen, approved by the MHRA in April 2026, follows the same staged philosophy with its own titration path.

How quickly semaglutide begins to affect appetite varies between individuals. This page on semaglutide's working timeline covers the pharmacokinetics in plain terms. And if you're comparing this injection format with Ozempic (which is also semaglutide but licensed for type 2 diabetes rather than weight management) the comparison page sets out the licensing distinction clearly.

Cost is a reasonable question once you understand the treatment itself. The Wegovy cost page covers what private treatment typically involves and why the price varies by dose and provider. If you're considering whether Wegovy is the right route for you, our weight-loss treatment overview sets out the options available, and you can check your eligibility with our prescribers at any point, free, with no commitment.