How to inject Mounjaro
A doctor’s step-by-step guide
Time to read: 12 min
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If you’re about to take your first Mounjaro injection, it’s completely normal to feel a little unsure about how it works.
I understand that giving yourself an injection for the first time can feel a little intimidating. That’s a very common concern. The good news is that the Mounjaro pen is designed to be straightforward to use, and most people find the process much quicker and easier than they expected.
In this guide, I’ll walk you through the steps so you can feel confident giving your injection safely and comfortably.
If you prefer visual instructions, you can also watch our video showing exactly how the injection works.
Information on this page
Before you inject
Before taking your dose, there are a few simple things you should do to prepare.
First, wash your hands thoroughly with soap and water.
Next, check the injection pen. Make sure:
It’s important to take a moment to double-check your dose before each injection, as this can change over time as you move through your treatment plan.
If your pen has been stored in the refrigerator, allow it to reach room temperature for around 30 minutes before use to make the injection more comfortable.
Avoid heating the pen or placing it in hot water. If the medicine is frozen or cloudy, do not use it.
Storage reminder
Store Mounjaro in the refrigerator (2–8°C). Do not freeze it. If you need to carry it with you, it can be kept at room temperature (below 30°C) for up to 30 days, but avoid leaving it in a hot car or in direct sunlight.
Where to inject
Mounjaro is injected under the skin (subcutaneously).
The recommended injection areas are:
- the stomach (abdomen)
- the front of the thigh
- the upper arm
Most people find the stomach or thigh the easiest places to inject.
Try to avoid injecting into the exact same spot each week. Rotating your injection site can help reduce irritation or soreness.
Here I’ve illustrated the recommended Mounjaro injection sites.
Do not inject into skin that is:
- bruised
- tender
- scarred
- irritated
Priming your pen
Each pen needs to be primed before it can be used for the first time. Follow these instructions before your first injection:
- Attach a needle to the top of your pen.
- Remove both caps from the needle.
- Turn the dose selector at the bottom of the pen until you hear two clicks.
- With the needle pointed upwards, tap the pen a few times to collect air bubbles.
- Press the dose selector until it stops. If done correctly, you should see a small drop of liquid at the top of the needle and you should see ‘0’ in the dose window.
Once your pen is primed, you can safely inject the medicine.
Injecting Mounjaro: step-by-step instructions
Each pen contains four doses, and a new needle should be used for each one. To use the pen safely, make sure to follow these steps:
The injection usually takes around 10 seconds, and the process is easy once you know how to do it.
Remember
Mounjaro is taken once weekly. Try to take it on the same day each week to help keep your routine consistent.
What you might feel during the injection
The injection is most commonly described as feeling like a small pinch or mild sting that lasts only a few seconds. In my experience, most people are relieved once they've done it for the first time.
Some normal reactions after the injection may include:
- mild redness at the injection site
- slight swelling
- a small drop of blood
- minor bruising
These effects are usually mild and disappear within a short time.
What not to worry about
When people give their first weight loss injection, they often notice small things and wonder if they’ve done something wrong.
I hear this a lot, and I want to reassure you that in most cases, these are completely normal:
- a tiny drop of medicine on the skin after the injection
- mild soreness at the injection site
- a small air bubble in the pen
- a small red mark after removing the pen
If you are unsure about anything, contact your prescriber for advice.
If you miss a dose
If you miss a scheduled dose of Mounjaro, you can still take the injection if less than 4 days have passed since the missed dose.
If more than 4 days have passed, skip the missed dose and take your next injection on your usual scheduled day.
You should never take two doses at the same time, and do not take more than one dose within the same week.
When to contact a doctor
While some mild discomfort is usually nothing to worry about, some reactions may require medical help. Contact a doctor or healthcare provider if you experience:
- severe or persistent pain at the injection site
- signs of infection (such as warmth, pus, or increasing redness)
- severe allergic symptoms
- unusual or severe side effects
If you are unsure whether something is normal, it is always safest to seek medical advice.
Remember…
- Giving yourself an injection for the first time can feel unfamiliar, but most people quickly become comfortable with the process.
- Take your time, follow the steps carefully, and remember that the injection pen is designed to make the process as simple as possible.
- If you ever feel unsure about how to use your medication, you can always reach out to your healthcare provider for some additional assistance or advice. Remember, we’re here to help.
Also Read: Foods to Avoid During Weight Loss Treatment: A Practical Guide
Frequently asked questions
Does Mounjaro hurt?
How long should I hold the Mounjaro pen in place?
What if I inject incorrectly?
What if I see a small drop of blood?
What if liquid leaks out?
What if I hit muscle?
Can I inject it if the liquid is cold?
What if I feel anxious about needles?
Can someone else inject it for me?
Is there a secret 5th dose, or “golden dose”?
Further reading
Reviewed by Dr. Allyson Betts
Reviewed by Dr. Allyson Betts
Why you may not be losing weight on Mounjaro
Reviewed by Dr. Allyson Betts
Mounjaro side effects explained
Reviewed by Dr. Allyson Betts
Reviewed by Dr. Allyson Betts
Reviewed by Dr. Allyson Betts
Reviewed by Dr. Allyson Betts
Reviewed by Dr. Allyson Betts
Reviewed by Dr. Caroline Fontana
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