GLP-1 injection site reactions, and rotating sites
Redness, itching, bruising or pain where you inject. How often the labels report it for semaglutide and tirzepatide, and keeping track of where you injected.
What the labels report
In Wegovy's weight-loss trials, 1.4% of people on semaglutide had injection site reactions (itching, redness, inflammation, hardening, irritation) against 1% on placebo.
Zepbound's trials reported injection site reactions (bruising, redness, itching, pain, rash) in 6% to 8% across doses, against 2% on placebo. They were more frequent in people who developed antibodies to tirzepatide (11.3%) than in those who did not (1%).
Rotating sites
Both labels list the abdomen, thigh or upper arm (for Zepbound, the back of the upper arm when someone else does the injection). Keeping a record of where each dose went is the simple way to see whether reactions follow a particular spot.
Keeping a record
PepMe records the site with every dose you log, shows on a body map how long since each site was used, and suggests the next one in your rotation. A reaction can go in the Journal note, next to the dose it followed.
Sources
- Wegovy (semaglutide) prescribing information, revised 08/2025 (FDA)
- Zepbound (tirzepatide) prescribing information, revised 08/2026 (Eli Lilly)
Trial figures describe groups of people, not what will happen to you. PepMe keeps a record of what you log; it never suggests what to take. Talk to your prescriber about anything here.