Meet the Other Phone. Child-safe in minutes.

Meet the Other Phone.
Child-safe in minutes.

Buy now

Please or to access all these features

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.

Open pen for three months

12 replies

RockChik · 16/03/2026 11:08

I’m considering starting MJ again after a two/three month break. I’ve got some 5mg and 7.5mg pens stockpiled in the fridge, but obviously don’t want to start on such a high dosage. My concern is that I will be using the pen for about three months, and I know it’s supposed to be discarded after one month, but I obviously don’t want to waste such a lot of money. So my question is (at the risk of being lambasted) has anyone used a pen for that length of time with success and without issues?!

OP posts:
MeridaBrave · 16/03/2026 11:09

I’ve used for 11-12 weeks kept in fridge. No issues. I know it’s not within the guidance.

SilenceInside · 16/03/2026 11:24

Yes, there will be people who have used a pen for that length of time without apparent issue. That doesn't mean that you definitely won't have issues.

The risks are contamination and degradation. Scrupulous hygiene and keeping it in the fridge will reduce the risks, not eliminate them, so then it's your decision to take as to whether you personally are ok with those risks.

SexyFrenchDepression · 16/03/2026 11:56

There are certain providers and other countries that prescribe the pens for longer. I use currently for 8/9 weeks and had no issues.

Meladram · 16/03/2026 13:16

Yes, keep in fridge, wipe pen thoroughly with alcohol.
As PP, it's at your own risk, but I've used pens for 3 months been OK.

LegencyofMonsters · 17/03/2026 12:48

Yes, I keep the pen in fridge, wipe pen thoroughly with alcohol every time.
I've used pens for 3 months been fine.

steinwayto · 17/03/2026 13:05

Can you not just order one 2.5mg and then move to your 5mg?

ShrankLastWinter · 18/03/2026 18:42

I use mine for up to 6 months. My prescriber (a doctor-led service, not UK) says that in their experience the pens remain effective for that long. They prescribe 15mg pens for extended use at lower doses. At the moment I’m on a maintenance dose of 5mg from a 15 pen, so with residual ‘golden’ doses that’s maybe 15 weeks.

I note, however, that they don’t state that the pens remain safe for that long. They don’t risk making that claim.

I’m careful with hygiene and keep in fridge door. When I travel, I do so only with last doses from a pen, so I don’t risk warming a pen which I’ll need for another couple of months. I’m not particularly risk-averse and am ok with this degree of experimentation. I suggested to my doctor that I didn’t mind paying for monthly, but he said that’d be daft, so I trusted him. Not entirely sure why, since little in my experience has taught me to trust doctors.

So yes, it works, but guaranteed safe it ain’t.

SilenceInside · 18/03/2026 19:11

@ShrankLastWinter can I ask about storing the pen in the fridge door? What’s the reason for that? I was under the impression that the door is warmer and more variable in temp than the rest of the fridge.

ShrankLastWinter · 18/03/2026 22:33

SilenceInside · 18/03/2026 19:11

@ShrankLastWinter can I ask about storing the pen in the fridge door? What’s the reason for that? I was under the impression that the door is warmer and more variable in temp than the rest of the fridge.

Good question! Prescriber suggests door. I think because there’s no risk of it getting pushed to the back and freezing, which does render it unusable.

SexyFrenchDepression · 18/03/2026 23:16

SilenceInside · 18/03/2026 19:11

@ShrankLastWinter can I ask about storing the pen in the fridge door? What’s the reason for that? I was under the impression that the door is warmer and more variable in temp than the rest of the fridge.

In all the info I have read it says never to put in fridge door as the temperature isnt stable. I put in a non see-through box in middle of fridge and keep a small fridge thermometer on top of the box.

SilenceInside · 18/03/2026 23:26

Yes that’s what I do too @SexyFrenchDepression bar the fridge thermometer.

SexyFrenchDepression · 18/03/2026 23:28

SilenceInside · 18/03/2026 23:26

Yes that’s what I do too @SexyFrenchDepression bar the fridge thermometer.

Mine is a smaller (drinks) fridge and is supposed to be 0-10° but the dial doesnt correlate to the temp so I wanted to check it was right. I assumed middle of the dial would be 5°, but no apparently not it seems 😂

New posts on this thread. Refresh page
Swipe left for the next trending thread