Where to Inject Tirzepatide and Semaglutide: What the Labels Actually Say

Almost every page answering this question gives you the same three body parts — abdomen, thigh, upper arm — for every GLP-1, as though the drugs were interchangeable on this point. They are not. Read the two labels side by side and tirzepatide's is narrower than semaglutide's in a specific, practical way that changes what you can do by yourself.

What each label actually says

Tirzepatide's label (Zepbound) states: "Inject ZEPBOUND subcutaneously in the abdomen, thigh, or another person should inject in the back of the upper arm."¹ That sentence is doing something easy to skim past. It lists three sites, but it attaches a condition to the third one. The patient-facing section of the same label makes the split explicit: "You or another person can inject into your stomach (abdomen) or thigh."¹ Two sites you can do yourself; the upper arm is written as a caregiver's job.

Semaglutide's label (Ozempic) states: "Inject OZEMPIC subcutaneously in the abdomen, thigh, or upper arm."² Three sites, no condition attached to any of them, and no self-versus-someone-else distinction anywhere in that instruction.

So if you are injecting yourself, with no one to help: tirzepatide's label gives you two sites, semaglutide's gives you three. That is not a nuance invented here — it is the difference between the two sentences.

Why the back of the upper arm is the one that gets the condition

The label does not explain its reasoning, so this section is anatomy rather than a quoted claim. The back of the upper arm is the one site on that list you cannot easily see, reach at a square angle, and pinch to raise a fold of fat at the same time — the other hand is doing the injecting and the arm being injected is the one you would need to pinch with. Abdomen and thigh are both in front of you and reachable with either hand. Whether that is the label's actual rationale, it is at least consistent with which site got the qualifier.

Rotation is an instruction, not a suggestion

Both labels require it, in similar words. Tirzepatide: "Rotate injection sites with each dose."¹ Semaglutide: "Change (rotate) your injection site with each injection."² Neither is phrased as advice. Repeatedly injecting the same spot is what produces local thickening and, over time, unpredictable absorption from that spot — which is the practical reason the instruction exists on a once-weekly drug where it would be very easy to fall into a habit of one favorite place.

Does the site you pick change how much drug you get?

For semaglutide, this was studied rather than assumed. A population pharmacokinetic analysis of once-weekly subcutaneous semaglutide evaluated injection site among the covariates tested against drug exposure³. That is the reason a label can list three sites and let you choose freely between them: if one site delivered meaningfully more or less drug than another, it would have to say so, and it would have to tell you not to switch mid-treatment. Neither label does. Both tell you the opposite — to keep changing.

What that does not mean is that technique is irrelevant. Site choice being interchangeable is a statement about three correct subcutaneous sites, not a statement that depth and angle do not matter.

The part that applies to a compounded vial and not to a pen

Everything above is quoted from the labels of the branded, FDA-approved products. If you are using a compounded tirzepatide or semaglutide from a telehealth provider, you are not using either of those products, and the instructions that came with your vial are the pharmacy's, not the label's. They may match. They may not. Nothing obliges them to.

That gap matters more than it sounds, because the same gap shows up in the dose itself — our units-versus-milligrams explainer covers why a syringe marking is a volume and not a dose, and why "40 units" means a different amount of drug depending on whose vial you are holding. If you want to know what you are actually buying before you get to that point, our compounded semaglutide explainer and our compounded tirzepatide explainer cover what compounding does and does not guarantee, and our tirzepatide provider comparison reads each provider's pharmacy disclosure off its own site.

What to take from this

Use the label for the product you actually have. If that is Zepbound or Mounjaro, the abdomen and thigh are yours and the back of the upper arm is written for someone else to do. If it is Ozempic or Wegovy, all three are yours. Either way, move the spot every week, and if your vial came from a compounding pharmacy, the instruction sheet in the box is the one that governs — not either of the labels quoted here.