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Weight loss injections/treatments

Discuss weight-loss injections and treatments, including personal experiences. Mumsnet hasn't checked the qualifications of anyone posting here. You may wish to speak to a medical professional before starting any treatments.

Original poster

Faulty Mounjaro pen from MedExpress, anyone got replacement or refund?

18 replies

Scarlettpixie · 14/03/2026 15:37

Has anyone had a faulty pen and managed to get a refund from the supplier - in my case MedExpress?

I am on 15mg. I have been taking MJ since Oct 2024. I have never had a faulty pen before.

I came to jab yesterday, 2 clicks to prime and press - nothing came out. Tried again and it turned a little way but this time no clicks and the plunger is stuck. I have tried another needle and it's no different.

I messaged Med Express on their chat and they sent me a trouble shooting guide and said if it didn't work to send them a video which I did - showing the box and where the lines are and that the plunger won't move. This was yesterday morning.

I messaged again in the afternoon saying I was worried as obviously I was due to jab that day and they said they understood and would pass the case on to a senior team member. Then nothing and I don't know if they work weekends.

What do I do? I could try to extract some with a needle but I don't know if it will work as the red bit (where the needle goes in) is bulging slightly? I don't know if Med Express will want the pen back and be grumpy if I have tried this.

I also have a 12.5mg pen in the fridge. I could start that one but I don't want to inject 12.5mg when I am finding it hard enough on 15mg. I was saving that one for when I start to titrate down.

What will Med Express do? Will they replace the pen, will they want to see the faulty one first/at all? Are they good about this type of thing?

Arghhh - what to do! I don't really want to do nothing until Monday. Thoughts?

OP posts:
QueenOfHiraeth · 14/03/2026 16:29

Have you got any needles from a different batch? If you tried 2 that came in the same order I guess they could be a faulty batch.
I don't know what your options are here tbh. The half life is 5 days and, after some time on it, it takes quite some time to fall measurably so you could wait and chase again on Monday. Was the red bit bulging before you started the pen, if so, do not use it.
MedExpress are not the best company for customer service from what I've read online so good luck

Original poster
Scarlettpixie · 14/03/2026 16:58

I don’t know if the red bit was bulging before I started yesterday. I suspect trying to press the plunger may have caused it. This would be dose 2 from the pen so it worked fine last week.

OP posts:
AmandaBrotzman · 14/03/2026 17:00

I had a faulty pen, just used insulin needles to extract it. Annoying but not the end of the world. I don't see why a needle wouldn't work?

wizzywig · 14/03/2026 17:08

Hi. Ive had this (my pens through juniper). It was fixable but you go through your supplier and they'll tell you how to fix it

openall · 14/03/2026 17:14

When I was going away I extracted the first dose of a new pen to take with me in a syringe rather than the whole pen. I don't know if doing this prevented the pen from working but I couldn't get any more doses from it using needles and wasted a few trying. I did wonder if it was faulty from the outset but carried on with syringes until it was empty. I wouldn't have known who supplied it as I'd got a small stockpile in the fridge.

CandiedPrincess · 14/03/2026 17:25

AmandaBrotzman · 14/03/2026 17:00

I had a faulty pen, just used insulin needles to extract it. Annoying but not the end of the world. I don't see why a needle wouldn't work?

That’s what I did too.

Wildgoat · 14/03/2026 17:39

It’s nearly always the needle. You need to put a new one on. Thid morning It worked on the third, it’s unusual it happens, but it does happen, suspect it’s as it’s not on quite right,

Purplepixiedust · 14/03/2026 19:06

Thank you so much! I decided to try again. I forced the dial back to zero, added a new needle from another supplier and yay clicks!!! It worked perfectly and I am duly jabbed

VimtoDemon · 14/03/2026 19:11

I got a replacement pen for a faulty one like yours but I had to return mine and get another sent out and it took WEEKS.

In the meantime I ordered a new 15mg from them and got it first. I was about to take dose 3 of the new pen by the time the replacement arrived!!

If it was me I'd get some syringes and DIY. I couldn't believe they refused to send me a replacement before they even received the faulty one THEY supplied! I'd been a customer for over a year at the time so had spent thousands with them!

hoarahloux · 14/03/2026 22:50

The red bung bulging means that the pen is working - the pressure is building as you press the plunger down. The needle is the issue, it hasn't penetrated the red bung properly.

Use a different needle, and expect a spray of wasted medication as the pressure is released. Hopefully not much!

Lacee222 · 15/03/2026 05:52

How long can you keep the golden doses for?ivd got quite a few left in my fridge just relised about this didnt no you can extract whats left

AmandaBrotzman · 15/03/2026 05:55

Lacee222 · 15/03/2026 05:52

How long can you keep the golden doses for?ivd got quite a few left in my fridge just relised about this didnt no you can extract whats left

Umm well the pens are supposed to be discarded after 30 days so using the bonus dose makes it 30 days exactly. Lots of us use lower doses from higher dose pens meaning we use them for longer than 6 weeks with no adverse effects but it's a risk you need to decide on. Nobody knows if the medication degrades over time and becomes less effective, so if you inject any of the ones you've been storing you're running a small risk of it being less useful and also of infection due to the pens being open too long. However if they've been in the fridge that's a low risk. Why have you been keeping them in the fridge instead of binning them if you didn't plan to use the extra dose?

Lacee222 · 15/03/2026 07:38

AmandaBrotzman · 15/03/2026 05:55

Umm well the pens are supposed to be discarded after 30 days so using the bonus dose makes it 30 days exactly. Lots of us use lower doses from higher dose pens meaning we use them for longer than 6 weeks with no adverse effects but it's a risk you need to decide on. Nobody knows if the medication degrades over time and becomes less effective, so if you inject any of the ones you've been storing you're running a small risk of it being less useful and also of infection due to the pens being open too long. However if they've been in the fridge that's a low risk. Why have you been keeping them in the fridge instead of binning them if you didn't plan to use the extra dose?

Show quote history

Thanks for the reply, honestly dont no why ive kept them to be honest 🙂 suppose like you say it could be a risk,but then maybe not i might try one see how it makes me feel,im not 100% sure how i get these doses out and with them being a few diffrent strengths,how it works.
Ive been on off monjouro for nearly a year because of the costs.
So most times ive had to go back to the start with no effect what so ever off them.Im currently on 7.5 now but as I say no effect what so ever.Ive sold loads of clothes etc to be able to afford these jabs aswell as other things but unfortunately ran out of things to sell.
That's why ive been on off it as much sorry for the winge.

GloiredeDijon · 15/03/2026 07:45

A friend had a similar experience with Medexpress last year.

They took so long to sort it out that she had to buy a pen from another supplier because they were hell to deal with and she would have been too long without injecting.

They eventually refunded her two months later.

Suffice to say she stayed with the new supplier instead.

AmandaBrotzman · 15/03/2026 08:02

Lacee222 · 15/03/2026 07:38

Thanks for the reply, honestly dont no why ive kept them to be honest 🙂 suppose like you say it could be a risk,but then maybe not i might try one see how it makes me feel,im not 100% sure how i get these doses out and with them being a few diffrent strengths,how it works.
Ive been on off monjouro for nearly a year because of the costs.
So most times ive had to go back to the start with no effect what so ever off them.Im currently on 7.5 now but as I say no effect what so ever.Ive sold loads of clothes etc to be able to afford these jabs aswell as other things but unfortunately ran out of things to sell.
That's why ive been on off it as much sorry for the winge.

Show quote history

So these pens have been open for over a year in the fridge?
I'm generally pro being fluid with the guidelines on using pens outside of the strict guidelines but I wouldn't touch one that's been open for a year. Sorry, I think you should bin them all TBH.

Edit sorry I read your post properly and that's not what you said 🤦🏼‍♀️

Lacee222 · 15/03/2026 08:25

AmandaBrotzman · 15/03/2026 08:02

So these pens have been open for over a year in the fridge?
I'm generally pro being fluid with the guidelines on using pens outside of the strict guidelines but I wouldn't touch one that's been open for a year. Sorry, I think you should bin them all TBH.

Edit sorry I read your post properly and that's not what you said 🤦🏼‍♀️

Edited
Show quote history

It's ok no not had them for a yr?sorry probs the way I wrote it,ive been on off jabs for about a yr x

Nanda66 · 16/03/2026 10:02

I had an issue with a pen from MedExpress last week. I contacted them via chat and they could not have been more helpful. The issue was resolved in minutes and they gave me a credit towards my next order. Excellent customer service, I was really impressed. I was considering changing to another provider who offer maintenance but for now I’m sticking with them.

ThirdStorm · 16/03/2026 10:21

Buy syringes and extract it out. UKMedi sell what you need with quick delivery.

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