How to take semaglutide: the complete UK guide to using Wegovy correctly

What the trial guidance and the SmPC actually say about injection technique

The NHS semaglutide medicine page sets out the basics clearly: each Wegovy pen is pre-filled and pre-set to one dose. There is no dial to turn. You press the pen firmly against clean skin, press the button, and hold it in place for the seconds stated in the leaflet — the click you hear is the injection starting, not finishing. That detail trips people up on their first attempt.

Rotating your injection site matters. Abdomen, thigh and upper arm are all suitable. If you always use the same spot, the skin can thicken over time, which affects absorption. Moving even a few centimetres from last week's site is enough. Some people find it helpful to keep a rough mental note (left thigh, right thigh, abdomen) rather than tracking it precisely.

The needle should go straight in, at a 90-degree angle to the skin. There is no need to pinch the skin unless you are very lean and injecting into the abdomen. If you see a small red mark afterwards, that is normal. Blood means you caught a superficial vessel, it is not harmful, but reinjecting at a slightly different spot is fine. If you want to understand how semaglutide works once it enters the body, that page explains the mechanism of action in detail. For a closer look at what the injection process actually involves, the step-by-step guide to injecting semaglutide covers each stage in detail.

Dispose of used needles in an approved sharps container; never recap and discard loose in household waste.

When to inject, and what to do if life gets in the way

Picking a fixed day and sticking to it is the simplest habit most people can build. Sunday evenings, Monday mornings, whichever fits your week. If you want to understand why timing consistency affects how the medicine builds in your system, the guide to when to take your semaglutide injection explains the pharmacokinetics in plain language.

If you miss a dose, the Patient Information Leaflet is the authority on what to do, not a forum, not a search engine. As a general principle, the SmPC states that a missed dose can be taken up to five days after the scheduled day; if more than five days have passed, skip it and resume on your next scheduled day. Never double-dose. Decisions about adjusting your schedule belong to your prescriber.

Nausea is most common in the first week or two after starting or after a dose increase. It usually settles. Many people find taking the injection in the evening means any queasiness passes overnight. That said, if side effects are persistent or worrying, contacting your prescriber is the right move, not waiting to see what happens. Semaglutide is a GLP-1 receptor agonist that slows gastric emptying, which is partly why the early weeks feel different.

Storage: what happens between the fridge and the injection

Wegovy pens are refrigerated at 2–8 °C. They must not freeze; a pen that has frozen should not be used. The exact window for how long a pen can be kept at room temperature before use is stated in the Patient Information Leaflet that comes with your medicine, and that is where the definitive answer lives, not here, because the window can differ between pen formats and lot conditions. What is consistent: keep the pen in the fridge, take it out shortly before use, and check the leaflet for the specifics.

The pen should not be exposed to direct sunlight or heat. Leaving it on a sunny windowsill or in a hot car voids the guidance. If you travel frequently, the practical guide to using semaglutide day-to-day covers travel storage in more detail.

A word our prescribers hear regularly: people worry that a slightly warm pen means the medicine is ruined. In most cases it is not, but the leaflet thresholds are there for a reason. When in doubt, contact your prescriber or pharmacist rather than guessing. It is not a question worth skipping.

Side effects to know about, and when to get medical help

The most common side effects of semaglutide are gastrointestinal: nausea, diarrhoea, constipation, indigestion, vomiting and burping. These are most pronounced after starting treatment and after each dose increase, and they typically ease within a couple of weeks. Eating smaller meals, avoiding high-fat foods and staying hydrated all help.

More serious effects are less common but need prompt attention. Severe, persistent abdominal pain that radiates to the back, with or without vomiting, can be a sign of acute pancreatitis. Get medical help quickly if that happens. The MHRA's Yellow Card scheme is the place to report any suspected side effects, and patients can use it directly, not only clinicians.

If you feel anxious about injecting for the first time, that is completely understandable. Most people find the auto-inject mechanism far less uncomfortable than they anticipated. The concern beforehand is usually worse than the injection itself. Detailed injection guidance is also available on the how-to-take-semaglutide-injections page.

Semaglutide is not recommended during pregnancy, whilst breastfeeding, or if you are actively trying to conceive. It is not licensed for under-18s. Anyone considering treatment should discuss their full medical history with a prescriber. If you are thinking about whether this treatment suits your situation, speaking to our prescribers is the right starting point.