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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.

Using a 5mg pen for 8x2.5mg doses??

42 replies

Mumof4rugrats · 09/04/2025 19:21

Iv been using mounjaro for 3 weeks now and due to order my next pen, my husbands wanting to try it and it’s going to work out pricey for us both, I’m happy to stay on 2.5mg as it’s working great for me, I was wondering could I get away with ordering a 5mg pen and splitting it into 8x2.5mg doses, 4weeks for my husband and 4weeks for me… (obviously I’d order extra needles), or would the pen lock after 4 doses? TIA 😊

OP posts:
TheArcher · 11/04/2025 11:29

Sorry but I think using the same pen for 8 weeks is madness.

WeAllHaveWings · 11/04/2025 11:46

Thisshirtisonfire · 11/04/2025 01:51

I've done this but I'm worried by the pen saying it's out of date after 30 days.
I ordered the 5 pen thinking I should move up but I've had such strong suppression on 2.5 I decided against doing the full 5 dose and just counted the clicks for a half dose.
Obviously if I use it for 2.5ml doses it's going to last 8 weeks instead of 4...
So much longer than 30 days.
Have you had any issue with this?

I use my 5mg pen for 6 x 3.75mg doses on days 0,7,14,21,28,35.

I am comfortable with my own risk assessment, keeping pen in fridge and going 5 days over. I personally would not use a pen for longer. It is up to you to research and assess the risks for you personally.

Asking someone else if they had any issues (obviously they didn't because they do it), or relying on any form of social media, is not a robust way of researching the potential risks for taking a prescription only medication to determine if you are happy to accept them.

Jojobaker0503 · 03/12/2025 22:05

a 5mg pen into smaller doses 2.5 = 8 doses this is great for people who cant tolerate the 5mg yet so they do smaller doses instead from sed pen
This is what im thinking of doing not only because I don't want to move up entirely yet plus its the cost its cheaper to buy the 5mg and split it into 8 doses by 30 clicks each time each week
Hope this helps

Jojobaker0503 · 03/12/2025 22:11

How many clicks is 3.75? Im not sure if it want to do 2.5 from 5mg pen yet might go up slowly ..im not starting it till my 2.5 pen is used so will be next month January

Lilacdreamowl · 04/12/2025 00:04

is this rage bait?

SexyFrenchDepression · 04/12/2025 10:06

I have researched this a bit recently. In other countries they prescribe higher dose kwikpens for micro dosing so it obviously is ok. If kept in the fridge and no cloudiness etc, plus use good hygiene there is no reason itll be an issue. In the UK doctors generally dont prescribe this however I have heard of medics saying it is fine.

For you and your DH practically it'll be fine, you wouldnt use the pen over 30 days and as long as you clean the seal each time and use new needles then it is likely to be fine.

However you may have an issue with people providing them if you use 1 every 2 months.

SexyFrenchDepression · 04/12/2025 10:07

Jojobaker0503 · 03/12/2025 22:11

How many clicks is 3.75? Im not sure if it want to do 2.5 from 5mg pen yet might go up slowly ..im not starting it till my 2.5 pen is used so will be next month January

Edited
  1. I went up to 3.75mg today. I am planning on using all the medication from the pen so cld be up to 7 doses.
SexyFrenchDepression · 04/12/2025 10:10

IHateMozzies · 09/04/2025 20:53

I would personally buy your own pens. It needs to be on both your health records in case anything happens.

It feels a bit icky sharing pens!….even if you do share other bodily fluids.

Moving up to the higher dose and taking less is definitely an option. I’ve been taking 6.25 out of my 7.5 pen. It will lock after the total amount of clicks (approx 248) not 4 uses.

You're not sharing anything using the pen, presumably they would use different needles?

MeridaBrave · 04/12/2025 10:21

It locks after 240/250 clicks. However not sure it’s hygienic to share a pen.

Either
A have a pen each and it lasts 8 weeks (obv keep in fridge)
B use syringes to extra the doses

SexyFrenchDepression · 04/12/2025 11:11

MeridaBrave · 04/12/2025 10:21

It locks after 240/250 clicks. However not sure it’s hygienic to share a pen.

Either
A have a pen each and it lasts 8 weeks (obv keep in fridge)
B use syringes to extra the doses

I don't understand why it wouldn't be hygienic to share? Am I missing something obvious?

BamberGirl · 04/12/2025 11:34

I do this, the pen doesn’t lock. I would order one each and use individually though.
i actually get 9-10 2.5 mg doses with the extra and using a syringe.

KrankyKumquat · 04/12/2025 11:34

@Mumof4rugrats
You're literally asking complete strangers on SM whether you'll 'get away with it'. How can anyone answer that? You may fall foul of prescribing rules by not ordering a pen within the expected timescales, your husband may have a bad reaction, you or him might get an infection from sharing a pen and there being cross contamination, you might get caught illegally sharing a prescription, you might both get slim and save a ton of money - all of these things are theoretically possible. What would you like us to say?

KrankyKumquat · 04/12/2025 11:39

God, don't you love it when you reply to a post which you didn't notice had been resurrected after 7 months🤣.

SilenceInside · 04/12/2025 11:47

@SexyFrenchDepression when you attach a needle to the pen and inject into your body there is an open channel, albeit tiny, between your body and the pen vial. You can get back flow through that channel, where body fluids go back into the vial, too small to be visible. That's what can contaminate the medication, which is why there are the storage instructions and usage time limit for an "in use" pen.

SexyFrenchDepression · 04/12/2025 11:49

SilenceInside · 04/12/2025 11:47

@SexyFrenchDepression when you attach a needle to the pen and inject into your body there is an open channel, albeit tiny, between your body and the pen vial. You can get back flow through that channel, where body fluids go back into the vial, too small to be visible. That's what can contaminate the medication, which is why there are the storage instructions and usage time limit for an "in use" pen.

Ah ok, that makes sense thank you.

HappyWineDay · 05/12/2025 09:08

SilenceInside · 04/12/2025 11:47

@SexyFrenchDepression when you attach a needle to the pen and inject into your body there is an open channel, albeit tiny, between your body and the pen vial. You can get back flow through that channel, where body fluids go back into the vial, too small to be visible. That's what can contaminate the medication, which is why there are the storage instructions and usage time limit for an "in use" pen.

I guess you could use only syringes each time if you wanted to avoid that and were determined to share.

PearlTeapot · 05/12/2025 21:24

Yes buy a 5, share the pen, you can get 9/10 doses out of it- BUT USE NEEDLES not the pen needles ok?

Due to risk of bacteria or blood or something going back into the pen.

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