If the injection is the part of Mounjaro that worries you most, you are in very good company. Most people find the idea far more daunting than the reality, and after the first one or two they barely think about it again. This guide walks you through exactly what to expect and how to give your first injection calmly and correctly. For the wider picture of treatment, see our complete guide to Mounjaro.
Mounjaro is a once-weekly injection just under the skin of your stomach, thigh or upper arm. Let the pen come to room temperature, choose and clean your spot, press the pen against the skin and hold it until the dose finishes, then pop the pen in a sharps bin. It takes under a minute, and most people feel little more than a small scratch.
It is more nerve-wracking than it is hard
The Mounjaro pen is designed for people injecting themselves at home for the first time. You do not draw anything up or measure a dose; the pen is pre-filled and does the work for you. The needle is very short and fine, far smaller than the ones people picture, and it goes into the fatty layer just under the skin rather than into muscle. Nerves before the first go are completely normal, and they fade fast once you realise how simple it really is.
Before you inject: getting ready
A calm few minutes of preparation makes all the difference. Taking your pen out of the fridge a little while beforehand is the single biggest comfort tip, because an injection at room temperature stings far less than a cold one.
How to give your injection, step by step
Every pen comes with its own instruction leaflet, and you should always follow that, but the routine is much the same each time.
Where to inject
Mounjaro goes into the fatty tissue just under the skin in one of three places: the stomach (keeping a little away from the belly button), the front of the thigh, or the back of the upper arm. Rotate where you inject each week rather than using the same exact spot, which keeps the skin healthy and comfortable. Many people find the stomach the easiest to reach and the least sensitive.
What it actually feels like
Most people describe it as a tiny scratch or a brief pinch, and plenty feel almost nothing at all. Because the needle is so fine and the injection is shallow, it is very different from having blood taken or a vaccination in the muscle. Any sensation is over in seconds. If you tense up, try a slow breath out as you press the button, which relaxes the skin and makes it easier.
After your injection
There is very little to do afterwards. Do not rub the area; if there is a tiny spot of blood, a moment of gentle pressure with a tissue is all it needs. Your used pen goes straight into a sharps bin, never the household rubbish, and your pharmacy can advise on returning a full bin. Then simply carry on with your day. Mounjaro works gradually in the background, so you will not feel anything dramatic straight after the injection itself.
Frequently asked questions
Does the Mounjaro injection hurt?
For most people it is a small scratch or brief pinch, and some feel nothing at all. The needle is very short and fine, and the injection is just under the skin. Letting the pen reach room temperature first makes it more comfortable.
Which injection site is best?
The stomach, front of the thigh, and back of the upper arm are all suitable. Many people find the stomach easiest and least sensitive. Rotate the exact spot each week to keep the skin healthy.
What if I see an air bubble in the pen?
Small air bubbles are normal in pre-filled pens and are not dangerous with an under-the-skin injection. You do not need to remove them. Just follow the pen instructions as usual.
What if a little blood appears afterwards?
A tiny spot of blood or a small bruise is common and harmless. Press gently with a tissue rather than rubbing. If bleeding or bruising is heavy or keeps happening, mention it to your prescriber.
Do I have to inject at the same time of day?
No. Mounjaro is once weekly on the same day each week, but the time of day is up to you, with or without food. If you need to, the day can be shifted as long as it is at least three days since your last dose.
What if I am frightened of needles?
This is very common and rarely a barrier. The pen hides the needle, the injection is quick and shallow, and a slow breath out as you press the button helps. Tell us at your assessment and we will talk you through it.
How do I dispose of the pen?
Used pens go into a sharps bin, never the normal bin or recycling. Your pharmacy can advise on obtaining a bin and returning it once full. Never try to remove or recap the needle.
This guide is general information and not a substitute for personal medical advice, and you should always follow the instruction leaflet supplied with your own pen. Mounjaro (tirzepatide) is a prescription-only medicine supplied after an online assessment and approval by a UK-registered independent prescriber.