Mounjaro injection sites: a complete rotation guide

Mounjaro (tirzepatide) is a once-weekly subcutaneous injection. You can inject it into three regions of the body: the abdomen, the front of the thigh, or the back of the upper arm. Where you inject affects how comfortable the shot is, how the medication absorbs, and — over months and years — the long-term health of the skin you’re using. Rotation isn’t optional. This guide walks through where to inject, why rotation matters, and a simple weekly plan you can actually stick to.

Why rotation matters

Injecting subcutaneous medication into the same spot week after week causes a condition called lipohypertrophy— firm, lumpy patches of fatty tissue under the skin. People with diabetes who self-injected insulin for decades taught the medical community a lot about this. Two practical consequences:

• Absorption changes.Medication injected into lipohypertrophic tissue can absorb erratically — sometimes slower, sometimes in a sudden release.
• The tissue stays changed for months. Once a patch becomes lumpy, it can take two to three months of complete rest to settle back down.

Rotation prevents the problem from starting. It costs nothing and takes a few seconds of planning per week.

The three approved Mounjaro injection regions

1. Abdomen (most common)

The flat area around the belly button is the most widely used Mounjaro injection site. Stay at least two inches (about a hand’s width) away from the navel itself. The abdomen has plenty of subcutaneous fat in most adults and is easy to see and reach.

2. Front of the thigh

The middle third of the front-outer thigh, roughly between hip and knee. Many people find the thigh slightly more uncomfortable than the abdomen, but it’s a useful second region for rotation.

3. Back of the upper arm

The fatty area at the back of the upper arm, between shoulder and elbow. This region is the hardest to self-inject because you can’t easily pinch up the skin one-handed. If you have someone who can help, it’s a good third option.

A simple weekly rotation plan

The plan below is what we recommend in Akoma. The principle is simple: change region every week, change quadrant within the region every injection.

1. Week 1 — Abdomen, 3 o’clock (right of navel)
2. Week 2 — Right thigh, upper-outer quadrant
3. Week 3 — Abdomen, 9 o’clock (left of navel)
4. Week 4 — Left thigh, upper-outer quadrant
5. Week 5 — Abdomen, 12 o’clock (above navel)
6. Week 6 — Right thigh, lower-outer quadrant
7. Week 7 — Abdomen, 6 o’clock (below navel)
8. Week 8 — Left thigh, lower-outer quadrant

After eight weeks you’ve used eight different spots and no individual spot has been injected twice. Rotate the cycle. If you have help with upper-arm injections, slot those in as well to extend the rest period further.

How to inject Mounjaro: six steps

These are the steps Akoma walks users through, distilled from the official pen instructions. Always follow the printed Instructions for Use that came with your pen — this is a summary, not a replacement.

1. 1. Pick this week's body region. Choose one of three approved Mounjaro injection regions: abdomen, front of thigh, or back of upper arm. Plan to use the same region for one full week, then move to a different region the following week.
2. 2. Subdivide the region into clock positions. Mentally split the chosen region into four quadrants — for the abdomen, think 12, 3, 6 and 9 o'clock around the navel, staying at least two inches from the belly button. For thighs and upper arms, use upper-outer, upper-inner, lower-outer, lower-inner.
3. 3. Use a different quadrant each week. Even within a single region, never inject into the exact same spot two weeks in a row. Move to a new quadrant on the next injection. Most people on Mounjaro inject once weekly, so this gives each spot a four-to-eight-week rest.
4. 4. Avoid skin that is bruised, hard, lumpy or recently shaved. Skip any patch that looks bruised, feels firm or lumpy, is broken, sunburnt, or was shaved in the last 24 hours. Lumpy patches may indicate lipohypertrophy from past injections — let them rest for two to three months.
5. 5. Pinch, insert, hold, withdraw straight. Pinch up an inch of skin and subcutaneous tissue. Insert the Mounjaro pen needle at 90 degrees to the skin. Press and hold for the full count specified in your pen instructions (usually six to ten seconds). Withdraw straight — do not rub the site.
6. 6. Log the exact site immediately. Open your GLP-1 tracker and record the exact site (region and quadrant) along with the dose and time. This is the only reliable way to plan next week's rotation — memory alone fails inside a month.

What to avoid

• Injecting through clothing. Always inject into clean, exposed skin.
• Reusing pen needles. Each Mounjaro pen is single-use.
• Massaging the site afterwards.Don’t rub. Press gently with a clean tissue if it bleeds, then leave it.
• Injecting on the same day of the week if you’ve moved a dose.If you skipped or shifted a dose, talk to your prescriber about the new schedule. Don’t double up.

When to call your prescriber

Rotation problems and injection-site issues are usually mild. Reasons to actually phone someone:

• A site stays warm, red, increasingly painful, or develops a discharge 24+ hours after injection (possible infection).
• A firm lump that doesn’t soften over the following weeks.
• A sudden, large bruise with significant swelling.
• A sense that your usual dose is suddenly behaving very differently — much stronger or much weaker side effects — with no other explanation. This can occasionally be an absorption issue related to where you’re injecting.

Tracking sites without thinking about it

Remembering “which quadrant did I use three weeks ago?” from memory is hopeless. This is the specific problem Akomawas built around: tap your last site on a body diagram, and the app shows you which quadrants are due, which to rest, and which to skip. There’s nothing magical about it — the magic is just that the diagram exists and the data doesn’t live in your head.

Akoma is free to download on the Apple App Store and works worldwide.

Related reading

• GLP-1 side effects: what to track and when to call your clinician
• Best GLP-1 tracker apps in 2026: an honest comparison