Weekly GLP-1 pens are injected into the fatty layer under the skin. For Mounjaro, Wegovy and Ozempic, the usual injection areas are the stomach, thigh or upper arm.
The site does not need to become a source of panic. Check your dose, read the instructions that came with your pen, choose a reachable area, and rotate the exact spot each week.
In this guide
The three places you can inject
GLP-1 injections go just under the skin, which is why they are called subcutaneous injections. The approved areas are simple:
- Your stomach
- The front of your upper thigh
- The back of your upper arm
The upper arm is harder to reach on yourself, so most people use the stomach or thigh. If you want to use the back of your arm, it is usually easier and safer to have someone else do it.
Does the spot change how well it works?
For most people, no. Semaglutide reaches similar levels in the body whether it is injected into the abdomen, thigh or upper arm. Tirzepatide also shows similar exposure across those areas.
That means choosing your site is mostly about comfort, reach and consistency. Switching between approved sites does not mean changing your dose.
Getting the right dose matters more than choosing between stomach and thigh. Check the dose window or pen strength before you inject, not after.
The things that do matter
Stay around 5 cm clear of your belly button if you are using your stomach. If your dose involves more than one injection on the same day, keep those injections at least 5 cm apart.
Move the exact spot each week. You can keep using the same broad area, such as your stomach, but avoid using the same point of skin every time. Skip any skin that is sore, bruised, broken, scarred or irritated.
Do not inject into a vein or muscle. The short needles used with GLP-1 pens make that unlikely when you choose a fleshy area, but it is still part of the reason not to pick somewhere with very little fat under the skin.
If you also inject insulin, use a different injection site for each medicine.
A quick practical checklist
- Check the dose is set correctly before you do anything else.
- Pick a spot with a reasonable layer of fat under the skin.
- Stay around 5 cm clear of your belly button if using your stomach.
- Move to a different point each week, even within the same area.
- Skip sore, bruised, broken, scarred or irritated skin.
- Get help if you want to use the back of your upper arm.
- Use a different site from insulin if you take it.
Not every injection follows these rules
The word injection covers very different routines. GLP-1 pens go into fat just under the skin. Some testosterone replacement therapy injections are intramuscular and may be given deep into the buttock by a clinician.
None of the GLP-1 site guidance transfers across automatically. If you use more than one injectable medicine, treat each one as its own routine with its own instructions.
Bottom line
For weekly GLP-1 pens, stomach, thigh and upper arm are the key injection areas. The medicine works similarly across those sites, so focus on checking the dose, rotating the exact spot, avoiding unhappy skin and following the instructions packed with your specific pen.
Medical disclaimer
This article is for general information only and is not medical advice. Always follow the instructions supplied with your medicine and speak to your prescriber if you are unsure how or where to inject.
