Injection Site Reaction

What is an injection site reaction?

An injection site reaction is a localised area of inflammation, irritation and or redness.

What does it feel like?

It is usually an area of skin described as warm, red, itchy and/or uncomfortable. This can occur at any of the areas a patient would be expected to inject their GLP 1 medication – abdomen, upper arm or thigh.

Why does it happen?

These reactions are common and usually temporary. They can happen at any time during your weight loss/maintenance journey.

There are a number of theories as to why they may occur including:

• Both Mounjaro and Wegovy are biologic, protein based natural hormones. When injected our immune system may identify them as foreign attacking them, releasing histamine and triggering a localised reaction.
• Many nurses, have suggested it may be secondary to injection technique causing local irritation to the skin – this can be in the form of injecting too quickly, too aggressively or not rotating injection sites.
• It may not be due to the active ingredient itself, but the other substances present in the treatment such as preservatives/buffers causing a localised reaction.
• It may also be due to the individual’s allergy status, where there may be a mild allergy to the active ingredient or the other substances mentioned.

What can I do to help it?

You can try the following to help alleviate symptoms:

• Try an oral antihistamine to ease symptoms, on our website we do have fexofenadine available to order which has proven to be helpful amongst our patients.
• An over-the-counter topical steroid such as 1% Hydrocortisone cream which can be used for short term relief of symptoms.
• Please also remember to rotate injection sites to minimise potential adverse effects.
• Try adjusting your injection technique - avoid pressing the plunger too hard onto the skin or too fast for example.
• You could also try a different brand of needles to see if it helps, although there is no evidence to suggest this would make a difference.

When should I be worried?

If despite al of the above your symptoms persist, change or worsen. This includes feeling systemically unwell – headache, fever, vomiting, dizziness with a spreading rash.

This then requires urgent medical attention and we advise this is sought ASAP.