Injecting yourself for the first time feels daunting for almost everyone. By the second or third injection, most patients barely think about it. The Mounjaro KwikPen is specifically designed to be simple. You don't need to draw up a dose, attach a conventional needle, or see the needle at all during injection.

What you'll receive

Each Mounjaro KwikPen is a prefilled pen containing four weekly doses at your prescribed strength. It comes with single-use needles, attach a new needle for each injection. The pen should arrive cold-chain packaged. Check the packaging is intact before using.

Before your first injection

Read the patient information leaflet supplied with your pen. Wash hands thoroughly with soap and water. Gather: pen, one supplied needle, antiseptic wipe. Allow the pen to come to room temperature for 15 to 30 minutes before injecting, cold medication from the refrigerator is more likely to cause temporary stinging.

Choosing your injection site

Three suitable sites: the abdomen (stomach area, at least 5cm from the navel), the outer thigh, or the outer upper arm. Rotate your injection site each weekly dose, abdomen one week, thigh the next, for example. Within each site, choose a slightly different area each time to prevent lipohypertrophy (localised fat build-up from repeated injections). Avoid areas where skin is bruised, red, tender, scarred, or has stretch marks. Never inject into a vein or muscle, inject into the subcutaneous fat just beneath the skin surface.

Step-by-step injection guide

  1. Remove the pen cap and check the solution. It should be clear and colourless to slightly yellow. Do not use if cloudy, discoloured, or contains particles.
  2. Remove the paper tab from the outer needle cover. Screw the needle onto the pen until secure. Do not overtighten.
  3. Remove the outer needle cover and keep it nearby. Remove the inner needle cover and discard it.
  4. Dial the dose: turn the dose knob until you hear two clicks and the extended line appears in the dose window (prime position).
  5. Prime the pen: hold with the needle pointing upward, tap the cartridge holder gently to move air bubbles to the top, then press the dose button until it stops counting slowly to five. A small amount of liquid should appear at the needle tip. This confirms the pen is working correctly. The dose window will show zero after priming.
  6. Wipe the injection site with the antiseptic wipe and allow to dry fully.
  7. Turn the dose knob until it stops, the "1" icon should be visible in the dose window.
  8. Insert the needle into the skin at approximately 90 degrees. Push the dose knob firmly until it stops. Count slowly to five while holding the button. The zero icon must be visible in the dose window before removing the needle.
  9. Remove the needle from the skin. Do not rub the injection site.
  10. Replace the outer needle cover on the needle. Unscrew the needle from the pen and dispose of it safely in a sharps bin. Replace the pen cap.

After your injection

A small amount of blood or fluid at the injection site is normal. Mild redness, itching, or bruising typically resolves within a few days and is more common in the first few weeks of treatment.

Storing your Mounjaro pen

In the fridge: store between 2°C and 8°C. Keep away from the freezer compartment. Do not freeze. Keep away from direct light. Can be stored until the expiry date on the label.

Out of the fridge: once removed from the refrigerator, the pen can be stored below 30°C for up to 21 days. Avoid direct sunlight and heat. Do not return a pen to the refrigerator after it has been stored at room temperature.

After use: always remove and safely dispose of the needle after each injection. Do not store the pen with a needle attached.

What to do if you miss a dose

4 days (96 hours) or fewer since your scheduled injection day: inject as soon as you remember, then resume your normal schedule.

More than 4 days since your scheduled injection day: skip the missed dose entirely. Inject your next dose on the regularly scheduled day. Never take two doses in the same week. If unsure, contact your prescribing pharmacist.

Disposing of used needles

Used needles must be disposed of safely in a sharps bin, never in household rubbish. When your bin is full, seal it and arrange disposal through your GP practice or your local council's sharps collection service.

Common injection concerns

"I can't see the needle going in, is that normal?"

Yes. The KwikPen uses a very fine, short needle (typically 4mm to 6mm). Most patients cannot feel it entering after the first few injections. If the dose window does not show zero after injection, contact your pharmacist.

"I saw a bubble in the pen, is that a problem?"

Air bubbles are common in prefilled pens and do not affect the dose or safety. Priming the pen (step 5) removes air from the needle before injection.

"The injection site is painful, what should I do?"

Mild transient stinging is normal, particularly if the medication was cold. Allowing the pen to reach room temperature and using the antiseptic wipe correctly minimises this. Persistent or worsening pain at an injection site should be assessed by your pharmacist or GP.

When to see your pharmacist or doctor
  • Any doubt about whether your dose was delivered correctly
  • Injection site becomes increasingly red, warm, or swollen over several days, possible infection
  • Significant bruising or a lump that does not resolve within a few days
  • Struggling with self-injection, technique support is available; there is no need to manage this alone
  • Travelling internationally, advice on storing your pen without refrigeration for extended periods

References

  1. Mounjaro Summary of Product Characteristics, Eli Lilly, 2024.
  2. Mounjaro Patient Information Leaflet (PIL), UK version 2024.
  3. NHS England: guidance on self-injection technique for subcutaneous medications.

Reviewed by Jimah Alsaai MPharm, GPhC 2232652, Superintendent Pharmacist, Solira.