Where to Inject a GLP-1, and Why Rotation Matters

Three places, and only three. Your abdomen, keeping clear of the navel by a couple of inches. Your thigh, on the front rather than the inner or outer side. Or the upper arm, around the back over the triceps. The needle goes into the fat layer just beneath the skin — subcutaneous — and never into muscle or a vein. Rotate with every dose. That last instruction is the one people skip, and it is the one with consequences.

This is the same guidance across every approved GLP-1: Wegovy, Ozempic, Zepbound, Mounjaro, Saxenda, Victoza and Trulicity all direct the same three sites.^[1] Compounded preparations are injected the same way, though they arrive as a vial and a syringe rather than a pen, which adds a step and a measurement.

The three sites, and how to pick

There is no evidence that one site works better than another for these drugs, and the label explicitly allows changing both the site and the time of day without altering the dose.^[1] Pick what you can reach comfortably and reliably.

Why rotation matters more than the site

Injecting the same spot week after week causes lipohypertrophy: the fat under the skin thickens and scars into a firm, sometimes visibly raised patch. It is common, it is painless, and that is precisely the problem — people carry on injecting into it because it does not hurt.

Scarred tissue absorbs erratically. The same dose delivered into a lipohypertrophic site reaches the bloodstream unpredictably, so appetite suppression turns inconsistent and progress stalls without the drug or the dose being at fault. ⚠ The way this usually presents is as a plateau — and a plateau is the moment sellers pitch a dose increase or an upgraded tier. Paying more to solve an injection-technique problem is a bad trade, and it is a common one.

1. Move at least two inches from your last injection, every time.
2. Cycle across regions, not just within one. A workable pattern is abdomen, thigh, upper arm across roughly eight weeks, moving to a fresh spot within each region each time.
3. Feel before you inject. Run your fingers over the site. Anything firm, lumpy or raised gets skipped until it resolves, which can take months of leaving it alone.
4. Keep a record. Weekly dosing is easy to lose track of. Our rotation calendar exists for this, and a note on your phone works as well.

Vials and pens are not the same job

An approved product comes in a pen that dials a dose in milligrams. Most compounded GLP-1s come in a vial you draw from with an insulin syringe, which moves a measurement step from a factory to your kitchen table.

That is where the errors happen. FDA has documented patients receiving five to twenty times their intended dose from compounded semaglutide, largely because a vial is labeled in milligrams while a syringe is marked in units, and the number that converts one to the other depends on the concentration your pharmacy chose.^[2] If you are drawing from a vial, our units-to-milligrams guide is the arithmetic you need before the injection technique matters at all.

The rest of the technique, briefly

• Room temperature stings less. Taking the pen or vial out of the fridge 15–30 minutes beforehand is the single easiest comfort improvement.
• Clean the site and let it dry. Injecting through wet alcohol is what makes it burn.
• Pinch or not, depending on your build. With a short needle and adequate subcutaneous fat, a pinch is often unnecessary. Ask whoever prescribed it what applies to you.
• Hold for the count the pen tells you. Pulling out early leaves part of the dose on your skin, and you will not reliably notice.
• Dispose in a sharps container. Not the bin. Pharmacies generally take them, and most states have a disposal program.

Common questions