How to Inject Mounjaro with the Pen: a Step-by-Step Visual Guide

What do you actually need before you start the injection?

Before you pick up the pen, gather everything in one place: the KwikPen from the fridge, a fresh needle (the pack supplied with your treatment or a replacement needle pack if you've run low), an alcohol swab to clean the injection site, and a sharps container for the used needle afterwards. The pen itself does not come with a needle attached, you add one each time.

Take the pen out of the fridge a few minutes before you need it. Cold medicine injected straight from the fridge door can sting; letting it sit briefly at room temperature is the kind of detail that makes the second injection noticeably more comfortable than the first. Don't shake it, and don't remove the base cap until you're ready to attach the needle.

Check the liquid in the pen's window. It should be clear to slightly yellow. If it looks cloudy, discoloured, or contains particles, don't use that pen, contact your prescriber or our support team instead. Inspect the expiry date printed on the label. Satisfied on both counts? You're ready.

How do you attach the needle and prepare the pen correctly?

Peel the foil from a new needle. Screw it straight onto the pen's base, clockwise, until snug, but not so tight that you damage the thread. Pull off the outer needle cap (keep it for safe removal later) and then the inner needle cap. A small drop of liquid may appear at the needle tip; that's normal.

The KwikPen comes pre-set to your prescribed dose, so there's no manual dialling involved in the way some older insulin pens work. Confirm the dose indicator shows the correct strength for your current prescription stage, this is worth a second glance, especially during a dose-increase month. Our clinical team reviews each repeat order before dispensing and will flag any dose-change queries.

For a visual check of every step described here, the Mounjaro injection video guide on our site shows the pen preparation sequence in real time, which many patients find helpful before their first injection. If you'd like a more detailed walkthrough of the needle attachment stage in particular, our how to inject Mounjaro video guides you through the full process with close-up footage that's especially useful if this is your first time using the pen, and our Mounjaro how to use video is a great companion resource if you want a broader overview of the pen from start to finish.

Where exactly should you inject, and what does the technique feel like?

Choose one of the three licensed sites: the abdomen (at least two inches from the navel), the front of the thigh, or the outer upper arm. The upper arm is the trickiest to reach solo; the abdomen tends to be easiest for self-injection. Each week, pick a different spot, not just a different body part, but a slightly different point within that area. Giving the same patch of skin a break each cycle keeps it healthy.

Clean the spot with an alcohol swab and let it dry for ten seconds. Wet skin can sting. Then press the pen firmly against the skin, you don't need to pinch the skin up for these needles, though some people do by habit. Press the purple button and hold the pen still. You'll hear a click when the injection starts. Keep the pen pressed in place until the plunger has stopped moving, then count slowly to five before lifting the pen away. Rushing this step is the single most common cause of partial doses.

Withdraw the pen straight out. Don't rub the site. Replace the outer needle cap without touching the needle tip (scoop it on from the side), unscrew the capped needle and drop it directly into the sharps container. Then replace the pen's base cap and return the pen to the fridge. The how-to-take Mounjaro video includes a useful walkthrough of this post-injection routine if you'd like to watch the full sequence end to end.

What should you do if something goes wrong or the injection doesn't feel right?

A little bleeding or a small bruise at the site is normal and settles quickly. If you notice liquid on your skin after withdrawing the pen, it likely means the pen was moved before the count was complete, follow the guidance in your Patient Information Leaflet on what to do about a possible incomplete dose, and contact your prescriber if you're unsure. Don't re-inject without clinical advice.

Redness, itching or mild swelling at the injection site are listed side effects and usually resolve within a day or two. Persistent lumps under the skin are typically caused by repeatedly using the same spot, the rotation rule matters for exactly this reason. If you're curious about how much progress you might see early on, our page on Mounjaro injection weight loss in one month sets out what's realistic to expect as the medicine begins to take effect. For a broader overview of what to expect in the early weeks, the Mounjaro injection overview covers the full side-effect picture as well as how the medicine works once it's absorbed.

A small number of people experience a more significant local reaction or a systemic symptom (severe stomach pain that extends to the back, difficulty breathing, or signs of an allergic response) and those warrant urgent medical attention rather than a phone call to the pharmacy. The NHS tirzepatide patient information at nhs.uk/medicines/tirzepatide lists the full set of side effects and the thresholds for seeking help promptly. The MHRA's Yellow Card scheme at yellowcard.mhra.gov.uk is where you can report any suspected adverse effects, patients can use it directly, not just healthcare professionals.

If you have questions about your specific dose, timing or what to do after a missed injection, those are conversations for your prescriber rather than a general guide like this one. Patients treated through nume have priority aftercare seven days a week, so there's always someone to ask. For those still deciding whether Mounjaro suits their situation, checking your eligibility with our prescribing team is a good first step.