Red, itchy or bruised injection site

Why this page exists: this question comes up often in GLP-1 patient forums but rarely in search results. We sampled forum threads by title; we did not quote or identify any user.

What the labels report

On Wegovy, 1.4% had injection-site reactions (itching, redness, inflammation, hardening, irritation) against 1% on placebo.^[1] On Zepbound it was 6%, 8% and 8% at 5, 10 and 15 mg, against 2%, including bruising, redness, itching, pain and rash. Hypersensitivity reactions of any kind were 5% versus 3% on Zepbound.^[2]

Share with injection-site reactions, drug vs placebo.^[1][2]

What the labels say about sites

Both labels list the abdomen, thigh and upper arm as injection areas and say to rotate sites with each dose.^[1][2] How to inject is something the prescriber or pharmacist should show you; this page is not a how-to.

Signs of an allergic reaction

• Swelling of the face, lips, tongue or throat
• Trouble breathing or swallowing
• Severe rash or itching over the body, a very fast heartbeat, fainting

These are the signs of a serious allergic reaction listed in the label, and need emergency care.^[1] A spreading, hot, painful area with fever is a reason to be checked for infection.

The short version

Questions to bring to your prescriber

Print these or screenshot them. They are conversation starters, not a checklist of things to do.

• Can you or the pharmacist watch me inject once to check my technique?
• Is this reaction the kind that settles, or should we look at it?

Sources

Every number on this page traces to one of these. "Primary read" means the full paper or label was read; "abstract only" means only the abstract was available; "secondary" means the figure was taken from a named review.

1. Novo Nordisk / FDA. Wegovy (semaglutide) injection and tablets, prescribing information, revised 06/2026. label
2. Eli Lilly / FDA. Zepbound (tirzepatide) prescribing information, revised 08/2026. label

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