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How to Inject Mounjaro Safely: A Complete Guide

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If you’re interested yes yes in Mounjaro, you’re probably already aware of its potential health benefits. Mounjaro is one of several weight loss injections licensed for prescription in the UK, and can promote significant weight reduction by reducing appetite and calorie intake. There’s no doubt that Mounjaro is a highly effective weight loss tool, but how do you inject it?

Deciding to use an injectable medication requires careful consideration. While Mounjaro is perfectly safe to inject at home, it’s important to understand how to do so correctly. Here, we’ll discuss how to inject Mounjaro, how to use Mounjaro pens, and potential injection sites.

 

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Injection Sites for Mounjaro

Mounjaro is injected subcutaneously (under the skin) of the upper arm, upper thigh, or stomach, at least 5 cm from the navel. If you plan to inject yourself, the stomach and upper thighs are usually the easiest places to reach. If you want to inject into your upper arm, you may need someone else to help you.

You can use the same body part every week if you like, but you’ll need to use a different Mounjaro injection site within that area. If you also inject insulin, choose a different injection site for your Mounjaro dose.

How to Use Mounjaro Pens: Instruction Video

For a step-by-step guide on how to inject Mounjaro, watch the video below. If you'd prefer written instructions, our guide has you covered. 

 

 

 

 

How to Prepare for Mounjaro Injections

Getting to grips with how to inject Mounjaro is a straightforward process when you prepare beforehand.

Before injecting Mounjaro, you should gather your supplies, choose your injection site, and wash your hands. You should also inspect the pen for signs of damage and ensure you have the correct dose. Here's how to prepare for Mounjaro injections:

Gather Supplies

 

 

First, gather all the necessary items to administer your injection. These include:

Wash Your Hands

 

 

Wash your hands thoroughly with soap and warm water before you inject Mounjaro. This will reduce your risk of infection.

Choose and Clean the Injection Site

 

 

You can inject Mounjaro under the skin of your stomach (at least 5 cm from your belly button), upper thigh, or upper arm. Once you’ve chosen your injection site, clean the area with an alcohol wipe to disinfect the skin and limit your risk of infection. You should rotate your injection sites with every dose to prevent hard lumps from developing under your skin. Here are some specific tips for each potential location:

  • Stomach: Avoid scar tissue and stay at least two inches away from your belly button.     
  • Back of your upper arm: You may need someone to help you reach.      
  • Thigh: Choose a different area for every dose to minimise the risk of scar tissue or injection. 

Don’t inject into areas where your skin is irritated or bruised.

Inspect the Pen

 

 

Inspect your Mounjaro pen carefully before you administer the injection. Do not use the medication if the:

  • Medication name or dose strength is incorrect
  • Product has expired
  • Pen has visible damage
  • Medication is frozen, cloudy, discoloured, or has bits in it (it should be colourless or slightly yellow)

Don’t worry if you see little air bubbles in the medication, as these are removed during the priming stage described below.

 

Mounjaro

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  • Approved Weight Loss Treatment
  • Suitable for adults with a BMI of +30kg/m²
  • Pre-filled injection pen

Prices from £159.99

 

How to Prime Mounjaro Pens

Once the necessary preparations have been made, the next step in our guide on how to inject Mounjaro is the priming phase. This process is crucial, as it removes air bubbles from the medicine and ensures the pen is working correctly. Here's how to prime Mounjaro pens:

Remove the Cap

 

 

Remove the pen cap by pulling it straight off, and clean the inner seal with a swab.

Insert the Needle

 

 

You’ll need to use a new pen needle for each injection to minimise your risk of infection or needle blockage. Once you’ve selected a needle, pull the paper tab off the outer needle shield (but leave the shield in place). Next, fix the needle to the pen by pushing it straight on and twisting until it’s securely attached.

Now that your needle is attached to the pen, you can remove the outer needle shield. Underneath, you’ll find a smaller, inner needle shield. Remove and discard this, but keep the outer needle shield, as it can be reused.

Prime the Pen

 

 

To prime the Mounjaro pen for injection, slowly turn the knob until you hear two clicks and the extended line appears in the dose window. Next, hold the pen with the needle pointing up and gently tap the cartridge holder. This will cause any air bubbles to rise to the top of the cartridge.

Finally, release some medicine from the pen by compressing the dose knob and slowly counting to five. This process removes air from the cartridge, ensuring the pen operates properly. You'll know your pen is primed when a small amount of medicine appears at the tip of the needle. The ‘0’ icon must also be shown in the dose window. Do not inject medication into your body at this stage. 

Select the Correct Dosage

 

 

To select your Mounjaro dosage, turn the dose knob until it stops and a ‘1’ appears in the dose window. This indicates a 0.6 ml dose of Mounjaro.

Mounjaro is administered according to a specific dosing schedule, and the amount of tirzepatide in each 0.6 ml dose varies depending on your schedule. Mounjaro pens are available in six dosages: 2.5 mg, 5 mg, 2.7 mg, 10 mg, 12.5 mg, and 15 mg.

 

Mounjaro

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  • Approved Weight Loss Treatment
  • Suitable for adults with a BMI of +30kg/m²
  • Pre-filled injection pen

Prices from £159.99

 

How to Use the Mounjaro Pen

The final stage in our guide about how to inject Mounjaro is administering the injection itself. Once the pen is primed, you're ready to inject the medication. Get into a comfortable position before following the steps below:

Position the Pen

 

 

Prepare to inject your Mounjaro by positioning the needle over the skin of your chosen injection site. If you are nervous about administering your injection, you may tense up. Try to do something to relax, such as listening to soothing music. Sitting rather than standing can also help to relax your muscles.

Administer the Injection

 

 

Insert the needle into your skin and inject the medicine by pushing the dose knob until it stops. Slowly count to five while holding down the dose knob until a ‘0’ appears in the dose window. Don’t remove the needle until you see the ‘0.’

Remove the Pen

 

 

Gently remove the needle from your skin. Don’t worry if you see a drop of medicine at the tip of the needle; this is normal and won’t affect your dose.

Make sure you can see the ‘0’ in the dose window, as this indicates you have received the full dose. If you don’t see the ‘0’ icon, re-insert the needle and complete the injection. Don’t redial the dose or repeat the injection, as this could result in a larger dose than intended.

Once your injection is complete, you can carefully replace the outer needle shield. 

Check the Injection Site

 

 

Have a look at your injection site after you’ve administered Mounjaro. If you see a drop of blood, lightly press the injection site with a cotton ball. Finally, wash your hands again with soap and water.

How to Remove the Needle from Mounjaro Pens

You should always remove the needle from your Mounjaro pen before putting it away. Doing so helps prevent leakage and needle blockage, and stops air from entering the pen during storage.

To remove it, simply unscrew the capped needle from the pen and place it in a yellow sharps container. Never reuse needles. Your local council may be able to collect and dispose of used needles and other medical waste. Finally, replace the pen cap before storing your Mounjaro.

 

Mounjaro

Rated 0 out of 5 based on 0 reviews
Rated 0 out of 5 based on 0 reviews
  • Approved Weight Loss Treatment
  • Suitable for adults with a BMI of +30kg/m²
  • Pre-filled injection pen

Prices from £159.99

 

How to Inject Mounjaro: Frequently Asked Questions

Understanding how to inject Mounjaro is relatively straightforward once you are familiar with the procedure. However, you may still have questions, like ‘What if I forget to prime my pen?’ and ‘How do I know if I administered the dose correctly?’

We’ll discuss the answers to these questions and more below.

Do You Have to Prime Mounjaro Every Time?

It’s essential that you prime your Mounjaro pen before each injection. Completing this process removes air from the pen cartridge, ensuring you administer the correct dose. It also confirms that the needle is not blocked and the pen is working correctly. 

I Forgot to Prime My Mounjaro Pen. What Happens?

You should prime your Mounjaro pen before each injection to ensure the needle and pen are functioning properly. If you inject without priming the pen first, you may not receive the full dose of Mounjaro, or you could even end up breaking the pen itself. 

If you have concerns about any of your Mounjaro injections, reach out to our licensed clinicians for advice.

Can I Reuse Mounjaro Needles?

No, it’s not advised to reuse Mounjaro needles. Using a new needle for each injection reduces your risk of infection and needle blockage, things that can either impact your weight loss journey or your health. It’s therefore important to dispose of used needles in a sharps container after each use.

Can You Double Dose Mounjaro?

You must not take a double dose of Mounjaro. It won’t make the medication more effective, but it may lead to increased side effects. If you think you’ve taken too much Mounjaro, you should speak to a healthcare professional for advice.

For more information about the side effects of Mounjaro and how long they last, please check out our guides. 

How Do I Store Mounjaro?

Store any unused Mounjaro pens in the refrigerator (between 2°C and 8°C). Used pens, however, can be kept at room temperature (up to 30°C). You can store your Mounjaro pen at room temperature for up to 30 days after your first injection.

Keep your Mounjaro pen away from extreme heat or cold. If frozen, discard the pen. You should also store the pen in its original packaging to protect it from light exposure.

How to Know if I Injected Mounjaro Correctly?

Once you’ve primed your Mounjaro pen, you will turn the dosing knob until it stops and a ‘1’ icon appears in the dose window. This indicates a full 0.6 ml dose. After you inject Mounjaro, the dose window should show a ‘0’ instead. This indicates that you have successfully administered the full dose.

If you don’t see a ‘0,’ re-insert the needle and push the dose knob to inject the rest of the medicine.

Should You Let Mounjaro Warm Up Before Injecting?

You can inject Mounjaro straight from the refrigerator, if you like. However, allowing the medicine to warm up a little can make it more comfortable to inject. Don’t try to warm your Mounjaro pen by applying heat. Instead, let it sit at room temperature for 30 minutes before administering the injection.

Prescription Doctor: Your Reliable Weight Loss Partner

If you’re thinking about embarking on a weight loss journey, the good news is that you don’t need to go through it alone. Since 2013, we at Prescription Doctor have supported countless people in achieving their goals, and we stand ready to do the same for you. 

 

 

We understand that there’s no one-size-fits-all solution when it comes to weight loss. That’s why our team of expert clinicians take the time to understand your unique circumstances and recommend what they believe will be the best treatment options for you.

In addition, we offer a comprehensive weight loss consultation service designed to support you every step of the way. From providing guides on how to inject Mounjaro and suggested exercise routines, to recommending diet plans and tips and tricks for success, you can get it all with us.

But that’s not all. Our clinicians will also regularly check in with you to monitor your progress and help you stay on track. This even extends to recommending alternative solutions such as Wegovy and Nevolat if you’re not managing with Mounjaro. It’s all part of the service.

Ready to get started on your Mounjaro journey? Simply complete our online medical questionnaire, and our team will assess your suitability for treatment. If approved before 3pm on a weekday, your order will be dispatched for next-day delivery in discreet packaging. Begin your consultation today. 

 

Sources

Authored By

Kate Latham

Medical Content Writer
Kate has been a scientific content writer since 2017. With a BSc in Biology and a background in cancer research, she is adept at identifying the latest findings in medical research and utilising these

Published on: 01/05/2024 Re-Published on: 24/07/2025

Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist
Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Reviewed on: 24/07/2025
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