If you have noticed a small amount of liquid left in your Mounjaro pen after taking your four prescribed doses, this can be normal. The UK patient information leaflet states that a small amount of medicine may remain after all four doses have been correctly given and should not be used as an additional dose. If you are using a Mounjaro pen and wondering whether the pen is finished, whether the remaining liquid can be used, how the pen works, or how to dispose of it safely, this guide explains these points in plain language. It also explains when remaining liquid can be expected and when the appearance of the medicine or pen may indicate a problem.
Yes, Liquid Left in the Pen Is Normal
First, some reassurance. Seeing a small amount of liquid remaining in your Mounjaro pen after all four doses have been correctly given can be normal. The UK product information states that a small amount of medicine may remain in the pen after all four doses have been correctly given. The remaining medicine should not be used.
This does not necessarily mean that you have done anything wrong or missed part of your dose. To understand why liquid can remain, it helps to know how the pen works.
How the Pen Works, and Why Liquid Remains
The Mounjaro KwikPen is a multi dose pen. It contains four once weekly doses, so the same pen is used for four weekly injections before it is discarded. It is not a single use pen.
Before each injection, you follow the flow check procedure described in the Instructions for Use. Each Mounjaro KwikPen contains four doses of 0.6 ml that can be administered. The UK product information also states that some excess solution may remain in the pen after use. This remaining solution should be discarded and must not be used as an additional dose.
Once you have taken the four scheduled doses, any liquid still visible in the pen is not a fifth dose waiting to be used.
Can You Use the Liquid Left in the Pen?
No. The liquid remaining after your four doses should not be used as another dose. The UK patient information leaflet specifically states that a small amount of medicine may remain after all doses have been correctly given and instructs patients not to use the remaining medicine.
That means you should not try to use the leftover liquid as an additional dose. You should also not try to extract it with a syringe or use the pen in a way that is different from the Instructions for Use.
The mounjaro golden dose is not an additional dose recommended in the UK product information. After the four prescribed doses have been given, the remaining medicine should be discarded with the pen.
How Much Liquid Should Be Left?
There is no recommended amount of remaining liquid that you need to measure or check after the four doses have been given. The pen contains four doses that can be administered, and some excess solution may remain afterwards.
The amount left can look more noticeable than you might expect. You do not need to measure it or judge your treatment by how much liquid you can see in the pen. What matters is following the prescribed dose and the Instructions for Use.
If it looks like a large amount is left and you are not sure whether you have completed all four injections, check your injection record. If you are still unsure, speak to your pharmacist or prescriber rather than trying to use the remaining liquid.
How to Know When Your Pen Is Finished
Because some liquid can remain after the four doses, you should not use the visible liquid level to decide whether your pen is finished. Instead, keep track of the doses you have taken and follow the storage and disposal instructions.
- Count your injections. After four weekly doses have been given, the pen should be discarded, even if you can still see some liquid inside.
- Follow the four dose and 30 day instructions. The UK Instructions for Use states that a used pen should be discarded after 4 weekly doses or 30 days after first use, whichever comes first.
Keeping a simple note of your injection dates can help you keep track of your doses. If you are unsure whether you have completed all four doses, ask your pharmacist or prescriber for advice.
How to Dispose of Used Mounjaro Pens in the UK
Used Mounjaro pens should be disposed of according to local requirements and the advice of your healthcare professional or pharmacist. The UK Instructions for Use advises patients to dispose of the used pen as instructed by their healthcare professional.
A few simple points can help:
- Do not try to empty the pen. Do not remove the remaining liquid or attempt another injection from it.
- Dispose of used needles correctly. If you have used a separate pen needle, remove it after the injection and place it in a sharps disposal container as instructed.
- Follow local disposal advice for the pen. Your pharmacist, prescriber or healthcare professional can tell you how to dispose of the used Mounjaro pen in your area.
If you are not sure whether you need a sharps container or how to dispose of your used pen, ask your pharmacist or healthcare professional for advice.
When Liquid Might Signal a Problem
The presence of some liquid after the four doses can be expected. However, you should check the medicine before use and should not use the pen if the medicine appears abnormal or the pen is damaged.
Contact your pharmacist or prescriber for advice if:
- The medicine is cloudy, discoloured or contains particles.
- The pen appears to be damaged or is leaking.
- The medicine has been frozen.
- You are unsure whether the correct dose was given.
Mounjaro should normally appear clear and colourless to slightly yellow. If the medicine does not look as expected, do not use the pen until you have received advice.
If you think you did not receive the full dose, do not try to make up the dose using the leftover liquid or by changing your next dose yourself. Speak to your pharmacist or prescriber about what to do next.