If you are experiencing an issue with your Mounjaro®, this guide explains common causes, troubleshooting steps, and what support may be available.
Please ensure you carefully review the guidance for your specific medication, as Mounjaro® and Wegovy® pens work differently.
Mounjaro® Pen Support
Common Mounjaro® pen issues
Patients may experience:
Hard-to-press dose knobs
No medication flow during priming
Bent or blocked needles
Medication leakage
Burst or damaged red seal components
Blood visible inside the pen
Frozen pens
Damaged or contaminated pens
Lost doses
Important Mounjaro® priming guidance
Unlike Wegovy®, Mounjaro® pens should be primed before every injection.
Priming removes air from the pen and helps ensure the correct dose is delivered.
How to prime your Mounjaro® pen
Attach a new needle securely
Turn the dose knob until you hear 2 clicks and see the extended line in the dose window
Hold the pen upright with the needle pointing upwards
Tap the cartridge gently to move air bubbles upwards
Press and hold the dose button for 5 seconds to release a small amount of medication into the air
Confirm the dose window returns to “0”
A small droplet at the needle tip is normal and confirms successful priming.
Do not inject during priming.
Hard-to-press dose knob
A stiff dose knob is commonly caused by:
A blocked or bent needle
Incorrect priming
Turning the dose knob without a needle attached
Storage issues or contamination
What to do
Replace the needle with a new one
Reset the dose knob back to “0”
Repeat the priming process carefully
Using a new needle resolves many issues.
Red seal damage or leaking
If the red internal seal has burst, split, or the pen leaks significantly, the pen may no longer be usable.
Please stop using the pen and contact our team with:
A video or clear photographs of the issue
Confirmation of how many doses were successfully used
Blood inside the pen
Blood may occasionally enter the pen chamber during injection.
If this occurs:
Stop using the pen
Contact our team with photographs of the pen
Frozen, damaged, or contaminated pens
Do not use your pen if:
The medication has been frozen
The pen is cracked or damaged
The liquid appears cloudy, contains particles, or is discoloured
Mounjaro® solution should appear colourless to slightly yellow.
Lost Mounjaro® doses
If you believe a dose was lost due to a pen fault, our team may request photographs or video evidence to assess the issue.
If a confirmed pen fault is identified, compensation may be considered by our Customer Care Team.
Please note:
Replacement eligibility depends on the number of doses already used
Pens with 3 successful doses already used would not qualify for a replacement pen
Any compensation or credit is assessed on a case-by-case basis
If you have not successfully completed all 4 doses from your pen, you should remain on your current dose strength until you have completed 4 successful doses before increasing strength.
Please refer to the image below showing how the pen appears after each dose.
Preventing Mounjaro® pen problems
To help avoid issues:
Always use a new needle for each injection
Never store the pen with a needle attached
Always replace the pen cap after use
Store the pen within the recommended temperature range
Never press the dose button without a needle attached
Incorrect storage or use may damage the pen mechanism.
When to contact us
Please contact our Customer Care Team if:
Your pen is not functioning correctly
You believe your pen is faulty
You are unable to administer your medication
Your medication appears damaged or contaminated
You believe you have lost a dose due to a device issue
To help us assess the issue as quickly as possible, please include clear photographs or videos showing the pen and the issue experienced.
Important information
In some cases, we may need to arrange for the faulty or compromised pen to be returned to us for further investigation with the manufacturer.
For this reason, please do not dispose of your pen unless you have been advised by our Customer Care Team that it is safe to do so.
Where a return is required, our team will provide full instructions on how to return the pen safely.