Where to inject a GLP-1 — and why rotating sites matters

The body areas the labels list

GLP‑1 medications are given as a shot under the skin — what the labels call a subcutaneous injection. The MedlinePlus page for semaglutide describes it as a solution “in a prefilled dosing pen to inject subcutaneously (under the skin),” injected once a week.²

The labels list three body areas. For semaglutide (the medicine in Ozempic and Wegovy), the FDA label says to “inject subcutaneously in the abdomen, thigh, or upper arm,” and MedlinePlus echoes this: “Inject semaglutide in your upper arm, thigh, or stomach area.”^1,2

Tirzepatide (the medicine in Mounjaro and Zepbound) follows the same pattern. MedlinePlus notes it is “injected subcutaneously (under the skin)” once a week, and that it “can be injected in the abdomen, thigh or upper arm.”³

Why the labels say to rotate

The official instructions don’t just name where to inject — they say to keep changing the spot. The Ozempic Instructions for Use are direct about it: “Change (rotate) your injection site with each injection. Do not use the same site for each injection.” The label also tells users to “use a different injection site each week when injecting in the same body region.”¹

The other labels say the same thing in shorter form. MedlinePlus advises for semaglutide to “use a different site for each injection,” and for tirzepatide to “rotate injection sites with each dose.”^2,3

What rotation is meant to protect against

The reason most often given for rotating is to reduce skin problems from injecting the same patch too often. The most-discussed one is lipohypertrophy. Cleveland Clinic describes it as a lump of fatty tissue under the skin: “Repeated injections in the same area cause lipohypertrophy, which involves a lump of fatty tissue under your skin.” It happens, Cleveland Clinic says, “when a person injects insulin or another medication into the same patch of skin too many times.”⁴

Beyond being a lump you can see or feel, these patches can change how a medication is taken up. Cleveland Clinic notes that if you inject into an area with lipohypertrophy, “the insulin might be absorbed more slowly or quickly than expected.”⁴

The fix that’s generally recommended is exactly what the drug labels already ask for — rotation. Cleveland Clinic advises to “change injection sites each time” and to “space injection sites at least a finger width apart.”⁴

How Tonic fits in — and where to go for your technique

Because the labels ask people to keep moving the spot, it helps to have the last one written down. Tonic can log which site you used last, so that record lives in one place instead of in your memory. That’s a logging feature — Tonic is a companion app, not a medical provider, and recording a site doesn’t change anything about how a medication works.

For the parts that are personal — exactly how to give a shot, which area suits you, and what a rotation pattern should look like for your situation — the right sources are your clinician and the medication’s own Instructions for Use, which come with the pen and are written for your specific product. This guide describes what those documents say in general; it isn’t a substitute for them.¹