Where to do your Mounjaro shot — and how to get it right

What official guidance says about injection-site choice

The Mounjaro SmPC, published on the electronic Medicines Compendium, names three acceptable sites: the abdomen (avoiding a two-inch radius around the navel), the front of the thigh, or the outer upper arm. All three deliver the medicine subcutaneously (into the layer of fat just beneath the skin) which is exactly where tirzepatide needs to go to be absorbed at the right pace.

Rotation is not optional advice. Injecting into the same small patch of skin repeatedly causes lipohypertrophy: a palpable lump of scar-like tissue that absorbs tirzepatide unevenly. Clinical data from the SURMOUNT programme found the medicine highly effective when used as directed; that consistency of absorption depends, in part, on disciplined site rotation. A simple habit that takes under a minute: before you inject, feel the area lightly with two fingers. If you notice any firmness or a small lump from last week, move at least an inch away, preferably to a different site entirely.

You can also alternate between sides. The left thigh one week, the right thigh the next, counts as rotation. Some people find it easiest to keep a simple note in their phone (the date, the site, and which side) so they never have to guess. For further detail on the licensed sites and the rationale behind each, our guide to every Mounjaro injection site goes through the anatomy in plain terms.

Choosing between the abdomen, thigh, and upper arm

Each site has practical advantages depending on your circumstances. The abdomen is the most commonly used: it offers a generous surface area, is easy to pinch and see clearly, and absorbs tirzepatide reliably. Avoid the strip of skin right at the belt or waistband, compression from clothing can affect the injection and increase bruising.

The thigh is a good option if you find it easier to sit down while injecting, the front or outer area, never the inner thigh. It can be slightly more tender at the starter dose, but most people find this settles quickly as their technique improves. The outer upper arm is the third option; many patients who self-inject choose it less often simply because it is harder to see, though it is perfectly valid. A carer or family member injecting on your behalf may find the upper arm the most convenient site.

None of the three sites is clinically superior. The guidance does not rank them. What matters is that you work through them in a consistent rotation rather than defaulting to whichever feels most familiar. If you are unsure which site suits your body composition or lifestyle best, our detailed guidance on where to take your Mounjaro shot covers the practical differences between the abdomen, thigh, and upper arm and can help you decide what works for your situation. Questions about your individual technique are best put directly to your prescriber, that is precisely what aftercare is for.

Preparing the site and completing the injection safely

Good preparation takes less than two minutes. Wash your hands thoroughly first. The skin at the injection site should be clean, an alcohol swab wiped across the area and left to dry for 10–15 seconds is the standard approach; if you need to restock, alcohol swabs are available from our pharmacy. Never inject into broken skin, a bruise, a rash, or an area that is inflamed.

Pinch a fold of skin, this lifts the subcutaneous layer away from muscle. Press the KwikPen firmly against the skin, press the injection button, and hold for the full count specified in your Patient Information Leaflet. Releasing early can mean an incomplete dose. Once done, lift the pen straight out; pressing or rubbing the site afterwards is not necessary and can cause irritation.

Needle change is non-negotiable: a fresh needle goes on before every injection and comes straight off into a sharps container immediately after. Reusing needles blunts the tip, increases pain, and raises infection risk. A one-litre sharps container handles roughly 50 used pen needles and meets UK disposal requirements. Your local council or community pharmacy will tell you how to return a full container. For a step-by-step walkthrough of the full injection process, our Mounjaro injection technique guide covers every stage.

Storage, timing, and a note on cost

The KwikPen is stored in the fridge at 2–8°C until you are ready to use it. There is a permitted window for room-temperature storage, the exact duration is stated in the Patient Information Leaflet and varies slightly by formulation, so check yours rather than relying on a number you read online. Injecting a pen that has been left out longer than the stated window is not recommended; if you are unsure, contact your prescriber before using it.

Injection day itself can be any day of the week. The only requirement is consistency: the same day, roughly the same time, every week. Most people pick a day that fits a natural routine, a morning before breakfast, an evening before a quiet half-hour. That rhythm supports adherence, which the clinical evidence from the SURMOUNT trials consistently shows matters for outcomes.

If you are weighing up the ongoing cost of private treatment, the Mounjaro price comparison page gives an honest picture of how UK private pricing works and what a full-service prescription should include. And for a broader look at what Mounjaro involves as a treatment, the Mounjaro treatment overview is a good place to start.