Red, itchy or sore where you inject
The NHS lists itchy or red skin where you inject as a common side effect, and Mounjaro’s and Wegovy’s leaflets call injection site reactions common, up to 1 in 10 people. The NHS lists an allergic reaction as serious, with symptoms such as a swollen throat or tongue, a raised, itchy rash or difficulty breathing.
In their own words
What each source lists as injection site reactions, and how often it says they happen.
| Source | What it lists | How often |
|---|---|---|
| Mounjaro | Injection site reactions (e.g. itching or redness)Mounjaro KwikPen patient leaflet | Common (may affect up to 1 in 10 people)Mounjaro KwikPen patient leaflet |
| Wegovy | injection site reactionsWegovy FlexTouch patient leaflet | Common: may affect up to 1 in 10 peopleWegovy FlexTouch patient leaflet |
| Ozempic | such as bruising, pain, irritation, itching and rashOzempic patient leaflet | Uncommon (may affect up to 1 in 100 people)Ozempic patient leaflet |
| NHS | itchy or red skin where you injectNHS: Semaglutide | Common for both |
Worth knowing
A new spot each week
The NHS says change the place you inject each week; the same area is fine, just not the exact same spot each time.
On darker skin
The NHS lists itchy or red skin where you inject, and notes redness may be harder to see on brown or black skin.
A little blood
If blood appears where you injected, Wegovy’s and Ozempic’s patient leaflets say press lightly on the spot.
Pain where you inject
Mounjaro’s leaflet lists injection site pain as an uncommon side effect, which may affect up to 1 in 100 people.
Questions
Is a red, itchy patch normal?
The NHS lists itchy or red skin where you inject among the common side effects, and says speak to a pharmacist or doctor if a side effect bothers you or does not go away.
When is it something more serious?
The NHS lists an allergic reaction among the serious side effects, with symptoms such as a swollen throat or tongue, a raised, itchy rash or difficulty breathing. The NHS says call 111 if you think you might be having serious side effects.
Does moving the spot help?
The sources don’t say it prevents reactions. They do say to change the spot each time: the NHS each week, Mounjaro’s leaflet, if you use the same area, a different spot within it, and Wegovy’s not the same spot as last time.
Injection areas
Jabwise suggests where to inject next.
Log the area with each jab and Jabwise suggests the one you’ve used longest ago, on a simple body map, so moving the spot each week takes no remembering.

Sources
- Mounjaro KwikPen patient leaflet
- Wegovy FlexTouch patient leaflet
- Ozempic patient leaflet
- NHS: Semaglutide
- NHS: Tirzepatide
General information, not medical advice. Follow your prescriber’s guidance.
Getting real advice
We’re not doctors. This page sums up what the NHS and the official medicine information say, and can’t tell you what’s right for your body: your prescriber’s instructions and the leaflet in your box come first. More in our terms.
- Quoted from official sources, each one linked
- Sources checked 12 October 2026
- No dosing advice; your prescriber comes first
- A pharmacist, your doctor or NHS 111If you’re not sure how to use your medicine, or a side effect bothers you or won’t go away. NHS 111 if you think you might be having serious side effects, or you’ve used too much.NHS: SemaglutideNHS: TirzepatideNHS 111 online
- Report a side effectAnyone can, not only doctors.Yellow Card (UK)MedWatch (US)