How to Self-Inject Mounjaro Safely

Starting a weekly injection can feel daunting at first, but a calm, simple routine makes it much easier. With Mounjaro (tirzepatide), the pen is designed to be straightforward, and most people find their confidence grows after the first couple of doses. This guide walks you through a safe, steady method you can follow every week.

Mounjaro is given as a once-weekly injection just under the skin (a subcutaneous injection) using a multi-dose KwikPen that contains four weekly doses per pen. You’ll choose a day of the week, prepare your pen, pick a site such as your tummy or thigh, and give the dose in a few simple steps. We’ll cover where to inject, how to prepare, and little tips that make it smoother and more comfortable.

Where and how Mounjaro is injected

Mounjaro is injected into the fatty layer just beneath your skin, not into muscle. The usual sites are the abdomen (tummy), the front of the thigh, or the upper arm (if someone else is giving the injection). Rotating sites each week helps prevent soreness and skin changes.

• Abdomen: Anywhere around the belly button, but avoid the belly button itself and any irritated skin.
• Thigh: The front/outer area, roughly between one hand above the knee and one hand below the groin.
• Upper arm: The outer area, best if a carer injects.

Short pen needles are designed for the subcutaneous layer; keep the pen at 90° to the skin and avoid pressing so hard that you dent the skin, which can push the needle deeper than intended.

Get set: build a simple weekly routine

A calm, consistent routine reduces errors and makes injections feel ordinary. Before starting, wash your hands with soap and water and gather what you need: your KwikPen, a compatible new needle, an alcohol swab, and a sharps container.

• Check the pen label, strength, and expiry; the liquid should be clear, colourless to slightly yellow, and free of particles.
• The four-dose KwikPen delivers one fixed weekly dose; after the fourth dose, dispose of the pen.
• Never share your pen or needles with anyone.

If your pen looks damaged, the liquid is cloudy, or it’s past expiry, don’t use it.

Step-by-step: priming and injecting

Most people find the steps feel natural after a couple of weeks. Follow these in order, and try not to rush.

1. Prepare the pen and needle

   • Remove the cap and wipe the red inner seal with a swab.
   • Attach a new pen needle straight on and twist until tight; remove and keep the outer needle shield; remove and discard the inner needle shield.

2. Prime the pen (first use and as instructed)

   • Turn the dose knob slowly to the prime position as specified in the instructions for use.
   • Hold the pen with the needle pointing up, gently tap to move any air bubbles to the top, then press the dose knob until it stops and count to five.
   • You should see a small drop at the needle tip and the window should show “0”. If no drop appears, repeat priming as directed or change the needle and try again.

3. Choose and clean your injection site

   • Rotate sites each week; clean the skin with an alcohol swab and let it dry.

4. Dial and give the dose

   • Turn the dose knob until it stops at your weekly dose setting (the pen provides one fixed weekly dose per label).
   • Place the pen at 90° to the skin and insert the needle; press and hold the dose knob until it stops, then count slowly to five.
   • Check the window shows “0” before removing the needle. If it doesn’t show “0”, re-insert and finish the injection—do not redial the dose.

5. After the injection

   • Carefully recap with the outer needle shield and unscrew the needle; dispose of it in a sharps bin.
   • Replace the pen cap and store as directed for your next dose.

If vision problems make it hard to read the window or align the dose, ask a trained person to help with the pen.

Tips for comfort and confidence

A few small tweaks can make injections gentler and more reliable.

• Rotate sites: tummy one week, thigh the next, then the other side—keep a simple note so you don’t repeat the same spot.
• Skin fold: if you have very little subcutaneous fat or are using longer needles, gently lift a skin fold and inject at 90° to stay in the fatty layer.
• Steady pace: press the dose knob smoothly and keep the needle still while counting to five before removing it.
• Don’t rush priming: it helps clear air and ensures an accurate first dose.

Expert insights

“Getting the technique right—clean hands, a fresh needle each time, and rotating injection sites—prevents most issues and helps the medicine work as intended.” UK diabetes education resources also emphasise keeping the needle at 90° and waiting a few seconds before withdrawing to ensure the full dose is delivered.

Real-world experiences

Many users describe feeling nervous at the first try but say the steps quickly become second nature. After priming and counting to five with the pen pressed in, seeing the window show “0” can be reassuring that the full dose has been delivered. By week two, the routine often takes only a couple of minutes.

What to do if something doesn’t go to plan

• If the window doesn’t show “0”: re-insert and finish the dose without redialling.
• If no liquid appears during priming: repeat the priming steps as directed, change the needle if needed, and try again; if it still doesn’t work, contact a clinician or pharmacist.
• If the pen is damaged, expired, or the liquid looks cloudy/coloured: don’t use it; obtain a replacement.

Brief safety notes

Key Takeaways

• Use the abdomen, thigh, or upper arm (with help), rotating sites weekly to protect the skin and ensure consistent absorption.
• Prepare and prime the KwikPen as instructed; always attach a new needle and check the liquid is clear and in date.
• Inject at 90°, press and hold while counting to five, and confirm the window shows “0” before removing the needle.
• If the window doesn’t show “0”, re-insert and finish the dose without redialling; dispose of needles in a sharps bin.
• Each pen contains four weekly doses; after the fourth dose, discard the pen and start a new one as prescribed.

For pricing and availability, check our price comparison tool.

Sources

• Four-dose Mounjaro KwikPen approved for diabetes and weight management — MHRA
• Mounjaro (tirzepatide): Public assessment/background information — MHRA
• Mounjaro (tirzepatide) Patient Information Leaflet — Medicines.org.uk (emc)
• How to Use the Mounjaro (tirzepatide) KwikPen — Lilly UK
• Mounjaro Instructions for Use (US) — Eli Lilly
• How to Use Mounjaro: Official Consumer Guide — Mounjaro (Eli Lilly)
• Subcutaneous Injection: Self-Administration Guide — South Tees Hospitals NHS Foundation Trust
• Subcutaneous Injection Sites: Abdomen, Thigh, Upper Arm — York and Scarborough Teaching Hospitals NHS Foundation Trust
• Giving Subcutaneous Injections: Patient and Family Guide — Great Ormond Street Hospital (NHS)
• Forum for Injection Technique UK (5th Ed.) — FIT UK / Diabetes Specialist Nurse Forum