Overview
Starting mid-2026, you may notice that your MedExpress Mounjaro® KwikPen® looks slightly different from previous versions — this is an official, expected cosmetic update from the manufacturer, Eli Lilly, that does not affect your medication, dose, or injection process.
Use this article when you want to:
Understand what visual changes to expect on your next Mounjaro® delivery from MedExpress
Confirm how the new plunger alignment looks before and after use
Learn how to tell a normal cosmetic update apart from a genuine device fault
What Has Changed in the Pen's Design?
During a temporary transition period, you may receive either the original pen design or the updated pen design, depending on stock availability. Both versions are fully approved, authentic, and completely safe to use.
If you receive the updated pen style, you will notice three main visual differences:
Initial Plunger Position: Before your very first use, the grey plunger may sit slightly lower in the glass window than it did on previous pens. This is part of the design change and does not mean your pen is missing medication — it still contains four full, accurate doses.
Internal Components: Certain moving parts inside the window mechanism, including a longer internal extension piece behind the plunger, have been altered.
Clearer End-of-Use Indicator: Once you have injected your fourth and final dose, the plunger will extend much further down, sitting near the very end of the cartridge. This provides a clear visual confirmation that the pen is completely finished and ready to be thrown away.
What Has NOT Changed?
Because this is purely a manufacturing update to the plastic pen casing and internal track system, there are no changes to your actual medical treatment.
No change to the liquid medication formulation or its effectiveness.
No change to your weekly injection process or priming instructions.
No change to the number of doses (each pen still holds exactly 4 doses).
No change to the safety profile of your treatment.
Is the Leftover Liquid in My Pen a "Fifth Dose"?
Some patients online refer to leftover medication visible in the glass window after the final injection as a "golden dose" or "fifth dose."
Please be aware that the Mounjaro® KwikPen® is manufactured to deliver four fixed doses only. Any residual liquid left in the chamber after your fourth injection is a safety buffer, is not a managed dose, and is not intended for use. You should never attempt to extract, siphon, or inject this leftover liquid. The updated pen design has been explicitly changed to help you see when your 4 legal doses are finished, so you can safely discard the pen.
How Do I Identify a Genuine Pen Fault?
While a change in the position of the plunger or a different look to the internal plastic parts is completely normal, you should still monitor your pen for operational defects.
Normal Appearance Changes (No Action Required):
The grey plunger looks lower down the window than usual before the first dose.
The internal tracking rod behind the plunger looks longer or different.
The plunger rests completely at the bottom of the glass window after the 4th dose.
Signs of a Genuine Product Fault:
The pen arrives with cracked plastic casing, a broken mechanism, or a damaged outer box.
The dose selector dial is jammed or will not turn.
The pen will not prime correctly during your initial flow check.
Liquid is leaking heavily from the side of the pen or failing to deploy from the needle tip.
If your pen appears physically broken or fails to deploy your dose correctly during injection, do not use it and leave it as it is — MedExpress can help resolve this for you. For all standard appearance variations, you can confidently continue your weekly dosing schedule exactly as normal.