Wegovy is semaglutide, given as an injection once a week and licensed for weight management. The same active ingredient is also sold as Ozempic, which is licensed for type 2 diabetes rather than weight management, so the two products are not interchangeable even though they share an ingredient and both involve a weekly injection routine.

Reactions where the needle goes in are a recognised possibility with semaglutide injections. NHS guidance on semaglutide lists redness, itching, and swelling at the injection site among the side effects people may notice. Most descriptions of these reactions are mild and settle on their own, but that is a general statement about what has been reported, not a promise about what will happen for any one person, and it is not a reason to skip writing a reaction down just because it seems ordinary.

What an injection site reaction can look like

People describe a range of things: a small red patch, a raised or itchy bump, mild swelling, bruising, or a warm feeling around the area. Some notice it within minutes of injecting; others notice it hours later, sometimes the next day. The appearance can vary from one injection to the next, even at the same general site, and it can also vary between different sites you rotate between, which is one reason a single description like 'my usual reaction' is often less useful than it sounds.

Because the description matters more than a label like 'a bit red,' it helps to write down what you actually see and feel rather than deciding in advance whether it counts as normal. A reaction that looks similar to last week's but lasts twice as long, or one that appears in a place you have not injected before, is worth noting as its own entry rather than folded into a general impression.

A simple way to record it

  • The general site used (for example, abdomen, thigh, or upper arm), without needing exact coordinates
  • What you saw: redness, swelling, a bump, bruising, or a rash, and roughly how large it was, using something familiar like a coin or a fingertip for scale
  • When it appeared relative to the injection, and how long it lasted before it faded
  • Whether it was itchy, painful, warm, or otherwise uncomfortable, and whether that changed over the following day or two
  • Whether it happened after a specific pen or a new box, if you keep track of that, and whether the pen had been stored differently to usual

A dated note like this is more useful at a review appointment than trying to remember weeks later whether last month's reaction was worse than this month's. Memory tends to smooth out details like exact size and duration, which are often the details a prescriber actually wants.

What helps a prescriber, and what does not

A prescriber will usually want to know how often reactions happen, whether they are getting more or less frequent over time, and whether any single reaction has been unusually severe, spreading, or slow to settle compared with your earlier ones. Photos taken at the time, with a date attached, can be genuinely useful alongside written notes, especially if a reaction has already faded by the time you are next able to describe it in person.

This page cannot tell you whether to change how or where you inject, and it will not suggest a rotation pattern or technique adjustment. Those are questions for the person who prescribed or dispensed your Wegovy, or for the patient information leaflet that came with your pen, both of which are better placed to give guidance specific to your situation than a general recordkeeping page can be.

When to stop recording and get help

Seek urgent medical attention if a reaction spreads rapidly, is accompanied by fever, feels hot and increasingly painful, or if you notice signs of a severe allergic reaction such as facial swelling, difficulty breathing, or a widespread rash. Everyday soreness at an injection site is common enough to log calmly and mention at your next routine contact; a reaction that is getting worse quickly, spreading, or accompanied by feeling generally unwell is not something to wait out or simply add to next week's notes.