Mounjaro and injection site reactions: causes, tips and when to get help
Injection site reactions on Mounjaro (tirzepatide): why it happens, self-care measures and the warning signs that need medical help.
Get urgent medical help if:
- you have signs of a serious allergic reaction, such as swelling of the face, lips or throat, difficulty breathing or a widespread rash (call 999)
Call 999 or go to A&E in an emergency. For urgent advice, call NHS 111.
About injection site reactions on Mounjaro
Redness, itching, swelling or bruising where you inject can occur with injectable GLP-1 medicines and usually settles on its own.
Injection site reactions is listed among the commonly reported side effects of Mounjaro in our reference data.
Things that may help
- Rotate injection sites (stomach, thigh or upper arm, as your instructions allow)
- Use a new needle for every injection where your pen requires one
- Follow the injection technique in the Patient Information Leaflet
A pharmacist can advise on suitable over-the-counter options.
Speak to your prescriber if
- a reaction is spreading, very painful, hot or does not settle
- you notice lumps that persist at injection sites
Report suspected side effects through the MHRA Yellow Card scheme. Reports help the MHRA monitor the safety of medicines.
Frequently asked questions
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