How Do You Use Tirzepatide — and What Happens at Each Step

Step 1, Preparing your pen before the first injection

Before you pick up the pen, check the expiry date and inspect the solution through the clear window. It should look colourless to slightly yellow and free of particles. If anything looks off, don't use it, contact your pharmacy. Take the pen out of the fridge around 30 minutes beforehand; injecting at room temperature tends to be more comfortable than injecting cold.

Wash your hands thoroughly. Choose your injection site: the abdomen (at least two inches from the navel), the front of the thigh, or the outer upper arm. Clean the area with an alcohol swab and let it dry completely before you inject, wet skin can sting. Keep the pen cap on until you are ready.

A question our prescribers hear most weeks is whether it matters which site you choose first. It doesn't, what matters is that you rotate the site with every subsequent injection. Using the same spot repeatedly can cause lumps or changes in the skin that affect how reliably the medicine is absorbed.

For a fuller walkthrough of the injection technique itself, the step-by-step injection guide on our Mounjaro use page covers the KwikPen mechanism in detail, and if you want to brush up on the basics beforehand, our page on how you take tirzepatide is a good place to start. The Mounjaro KwikPen is the delivery device for tirzepatide in the UK, made by Eli Lilly.

Step 2, Giving the injection and what to expect immediately after

Remove the cap and press the pen firmly against your chosen site. Press and hold the button until you hear a click, then keep holding for a further ten seconds, this ensures the full dose is delivered. A small yellow indicator appears in the window to confirm the injection is complete. Do not rub the skin afterwards.

Dispose of the used pen in a sharps container, never in household waste. A 1-litre sharps bin is a practical choice for at-home use.

Some people notice mild discomfort, redness, or a small lump at the site. These are normal and typically resolve within a day or two. Nausea is the side effect people mention most often in the first days after starting or after a dose increase; it usually settles within a week or so. Eating smaller meals and avoiding rich or fatty food can help your system adjust. The tirzepatide overview page covers the full side-effect picture, and the NHS tirzepatide medicines page lists what to watch for in plain language.

Step 3, Sticking to your weekly schedule and managing dose increases

Choose a day of the week that suits your routine and keep to it. If you need to shift your injection day by a day or two, that is generally fine, but you should ask your prescriber rather than adjust unilaterally. If a dose is missed, check your Patient Information Leaflet for the guidance on what to do, do not double up on doses.

The dose ladder for tirzepatide runs from 2.5 mg through 5, 7.5, 10, 12.5, and up to 15 mg, typically moving up in four-week steps. The pace is your prescriber's call, not yours. Moving up too quickly is one of the most common reasons people experience unnecessary nausea. Your prescriber will review your weight, tolerance, and any side effects before recommending an increase, at nume, that review happens before every repeat order, not just at the start.

The goal of titration is to reach the highest dose you tolerate well. Some people do very well at 7.5 mg or 10 mg; others reach 15 mg over several months. SURMOUNT-1 (a pivotal clinical trial published in the New England Journal of Medicine) found an average body-weight reduction of around 20–21% at the 15 mg dose over 72 weeks, which gives a useful sense of what the use of tirzepatide at higher doses can achieve for people who reach and tolerate that level. Results in real life vary; a clinical trial provides a framework, not a guarantee.

For context on how this compares with other licensed options, the weight-loss treatment overview sets out the landscape. And if you're wondering about the cost of ongoing treatment, the Mounjaro cost and access page explains what a legitimate private price typically includes.

Step 4, Ongoing use, storage, and when to get medical help

Between doses, the pen lives in the fridge. The Patient Information Leaflet specifies the window during which it can be kept at room temperature, follow that, not a generalised number from the internet, because the exact figure can differ between dose strengths.

Tirzepatide carries a Black Triangle (▼), meaning it is subject to additional MHRA monitoring. That is routine for newer medicines and doesn't reflect a safety concern beyond what applies to similar drugs. You can report any suspected side effects via the MHRA's Yellow Card scheme, which is open to patients as well as clinicians.

Get urgent medical help if you develop severe stomach pain that radiates to your back, with or without vomiting, this can be a sign of pancreatitis, a known but uncommon risk with GLP-1 and dual-agonist medicines. Other reasons to contact a clinician promptly: signs of a serious allergic reaction, persistent vomiting that leaves you unable to keep fluids down, or gallbladder symptoms such as sharp pain in the upper right abdomen.

Tell any healthcare professional (including a surgeon or anaesthetist) that you are taking tirzepatide before any procedure, and if you have ever been unsure how to pronounce tirzepatide when speaking to a clinician, our guide on that is worth a quick look. For a broader picture of who is and isn't suited to this medicine, the Mounjaro information hub is a good next read. If you have already been assessed and want to know what the consultation process looks like at nume (sorry, at our pharmacy) the clinical team profile on our prescribers page explains who reviews your case.

Ready to talk through your suitability? Speak to our prescribers through a free consultation, reviewed the same day by a GPhC-registered Independent Prescriber.