Taking Mounjaro might feel daunting at first, but with clear steps and a little practice, it soon becomes a straightforward part of your weekly routine. This guide will walk you through every stage of the process, helping you feel confident and in control of your treatment.

The best Mounjaro injection sites

Selecting the best place to inject Mounjaro can help you feel more comfortable and make sure the medicine works as it should. 

The most popular areas are your stomach (keeping at least 5cm away from your belly button), the front of your thighs, or the back of your upper arms, though you may need someone’s help to inject into your arm. 

By changing your injection site each week, you can help avoid soreness and look after your skin.

How to inject Mounjaro

1. Wash your hands

Start by thoroughly washing your hands with warm, soapy water for at least 20 seconds, then dry them well. This simple step helps keep germs at bay and reduces the risk of infection.

2. Gather your supplies

Before you begin, make sure you have everything you need close at hand. The supplies you’ll need to inject are:

• Mounjaro pen
• New pen needle
• Alcohol swab
• Cotton ball or gauze

3. Check the pen

Take a moment to inspect your Mounjaro pen. Make sure it’s the correct medication and dose, and check the expiration date. Look through the pen window to ensure the solution is clear (or slightly yellow) and free from any particles or discolouration. If anything looks unusual, don’t use the pen and seek advice from your prescriber.

4. Choose where you want to inject

As we mentioned before, it’s time to pick the injection site. You don’t want to inject in the exact same spot every time, but it’s fine to stick to the same general area. This will be the stomach (keeping at least 5cm away from your belly button), the front of your thighs, or the back of your upper arms.

5. Prepare for injection

Clean your chosen injection site with an alcohol swab and let it air dry completely. Avoid blowing on the area, as this can introduce germs. This step helps keep your skin clean and reduces the chance of infection or irritation.

Begin by removing the protective cap from your Mounjaro pen. Next, use a fresh alcohol swab to gently clean the inner red seal of the pen. Always use a new needle with each injection; this helps prevent infections and keeps the needle from becoming clogged. Before you attach the needle, check it carefully to make sure it isn’t broken or bent. 

Remove the paper tab from the outer needle shield, but keep it aside for now. Take off the inner needle shield and safely dispose of it. Finally, screw the capped needle onto the pen by turning it clockwise until it feels completely secure and snug. 

6. Prime the pen

Your Mounjaro pen should be primed before every injection. 

Slowly turn the dose knob until you hear two clicks. You’ll see the extended line appear in the dose window, which is the correct position for priming. If needed, you can adjust the knob in either direction to line up the position you want with the dose indicator.

Hold your pen with the needle pointing upwards. Gently tap the cartridge holder to help any air bubbles rise to the top. Then, push the dose knob all the way in and hold it for a count of five to release a small amount of medicine into the air. Do not inject yourself at this stage.

Check the dose window to make sure the ‘0’ icon is displayed. If you don’t see a small drop of medicine at the needle tip after this step, repeat the priming process, but do not do this more than twice. 

If you still don’t see any medicine after two attempts, replace the pen needle and repeat the priming process once more.

7. Inject the medication

Turn the dose knob until it stops and the ‘1’ icon appears in the dose window. Gently insert the needle into your skin. To inject Mounjaro, push the dose knob all the way in until it stops, then slowly count to five while you keep holding the dose knob in place.

8. After the injection

After you have received your full Mounjaro dose, slowly pull the needle out of your skin. Always double-check your pen to ensure you have injected the dose fully. If the ‘0’ icon appears in the dose window, it means you have received the full dose of Mounjaro.

However, if this icon is not visible, you should carefully reinsert the needle into your skin and complete the injection without turning the dose knob again. If you are uncertain or have any concerns, it’s best to consult your doctor or pharmacist for guidance.

You may notice a little blood where the needle went in, or a drop of the medicine on the needle’s tip. Don’t worry – both of these are normal. 

Simply press a small piece of gauze or cotton wool gently onto the area for a moment. You might also see some slight bruising at the site, but this should fade within a few days. Both are common and nothing to be concerned about.

To remove the needle, gently place the outer needle shield back over the needle and dispose of it in your sharps bin.

Once done, put the cap back on your pen and store it safely until your next dose. If this is your fourth and final dose, discard your empty pen (without a needle!) in your regular household waste.

Mounjaro site reactions

Some people may notice a reaction at the spot where they inject Mounjaro, though this is not very common. In clinical trials, injection site reactions were reported in about 3.2% of people using Mounjaro, compared to just 0.4% of those given a placebo. 

These reactions are usually mild and may include redness, swelling, minor pain, or irritation. They typically resolve on their own within a day or two.

In addition to local site reactions, up to 1 in 10 people may experience hypersensitivity symptoms such as skin rashes, itching, eczema, swelling, or redness. 

If you notice any of these symptoms, it’s essential to let your prescriber know. They may recommend changing your injection site, lowering your dose, or using a soothing cream to help with irritation. Applying an ice pack after your injection or taking a mild pain reliever can also help ease discomfort.

Injecting Mounjaro should not be very painful. If you ever experience severe pain, significant swelling, or intense redness, seek medical advice, as this could be a sign of an allergic reaction that needs urgent attention.

What to do if you miss a dose

If you forget to take your Mounjaro dose, what you do next depends on how much time has passed. 

If it’s been four days or less since your scheduled injection, take the missed dose as soon as you remember. After that, continue with your regular weekly schedule, taking your next dose on your usual day.

However, if more than four days have passed since you missed your dose, skip the missed injection and take your next dose as planned on your usual day. 

Never take two doses close together or try to ‘catch up’ by injecting a double dose, as this can increase the risk of side effects. Always ensure there are at least three days between any two Mounjaro injections.

Once you’ve taken your next scheduled dose, you can resume your normal once-weekly routine. If you are ever unsure what to do, or if you have missed several doses, speak to your prescriber for advice.