Short answer: Weight-loss injections are given into the tissue under the skin (subcutaneously). There are three main approved injection sites: the abdomen, at least 5 cm away from the belly button; the front and middle of the thigh; and the outer back part of the upper arm.

Key takeaways

  • 3 main sites: the abdomen (right/left), thigh (right/left) and upper arm (right/left) give 6 rotation points.
  • Injecting into the same spot repeatedly leads to hardening of the tissue (lipohypertrophy) and disrupts absorption of the medicine.
  • The Haftra app remembers the previous site each week and shows the next rotation point visually.
  • Never inject into a muscle or a vein; inject only into the fatty tissue under the skin.

GLP-1 injections are given under the skin (subcutaneously). The sites listed in the product information are the abdomen, the front of the thigh and the outer upper arm. Choosing a different spot for each injection is recommended: this is called site rotation.

This page is for general information only and does not replace medical advice. The injection site, dose and duration are decisions for your GP or prescriber alone. The patient information leaflet for your own medicine takes priority over the general information on this page.

Which sites are used?

  • Abdomen: provided you stay about five centimetres away from the belly button.
  • Front of the thigh: the middle area, away from the knee and groin.
  • Outer upper arm: usually easier for someone else to inject.

The product information does not say that any of the three sites is more effective than the others. The choice largely comes down to which one you can reach comfortably.

Why is rotation needed?

Injecting into the same spot again and again can cause hardening and tissue changes under the skin. Absorption of the medicine can also vary in changed tissue; in other words, the same dose may behave differently from week to week. Rotation is there to prevent this.

Injection site reactions such as redness, bruising and tenderness also become more noticeable when the same spot is used all the time.

How do you plan rotation?

A common method is to go round the three sites in turn and pick a different spot within each site too. For example, moving from the upper right quarter of the abdomen to the upper left quarter the following week means several weeks pass before you return to the same site.

If you do not record your injections somewhere, after a few weeks it becomes hard to remember which spot you used and when. This is exactly where rotation falls down in practice.

What should you watch out for?

  • Do not inject into skin that is red, swollen, hard, tender or broken.
  • The site should be clean before you inject.
  • Use a new, sterile needle for every injection.
  • Mild redness at the injection site usually goes away on its own; for lasting hardening or spreading swelling, see a doctor.

Keeping track of the site

Haftra shows how many days it has been since each of the six sites was last used and reminds you which site is next. It does not decide which site is healthiest; it makes it easier to follow the rotation instructions in the product information. It is free and can be used without creating an account.

iPhone, iPad and Apple Watch. Free.

Frequently asked questions

Where are weight-loss injections given?

The sites listed in the product information are the abdomen, the front of the thigh and the outer upper arm. The injection is given under the skin. On the abdomen, you need to stay about five centimetres away from the belly button.

Why is it given in a different site each time?

Injecting into the same spot again and again can cause hardening and tissue changes under the skin. Absorption of the medicine can also vary in changed tissue; in other words, the same dose may behave differently from week to week. Rotation helps keep absorption consistent.

Can I inject into the same site two weeks in a row?

A common method is to go round the three sites in turn and pick a different spot within each site too. The aim is for several weeks to pass before you return to the same site.

Which site is more effective?

The product information does not say that any of the three sites is more effective than the others. The choice largely comes down to which one you can reach comfortably.

Where do weight-loss injections hurt the least?

Because the abdomen usually has the most fatty tissue, it is the site that hurts least for most users.

Can I inject into my arm on my own?

Injecting into the arm is usually easier with someone else's help; if you are injecting on your own, the abdomen or thigh is the better choice.

Sources

  • EMA: Mounjaro (tirzepatide)
  • EMA: Ozempic (semaglutide)
  • EMA: Wegovy (semaglutide)
  • NHS: Obesity treatment
  • MHRA (Medicines and Healthcare products Regulatory Agency)

Last reviewed: 4 August 2026