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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.

Mounjaro users- which day of the week do you inject and side effects?

36 replies

WorriedMum210721 · 21/03/2026 14:47

Hi all!
I have mounjaro sat in my fridge and I was just wondering what day you all inject? I am usually a monday girly when it comes to starting any diet but I know this might not be the best time because of the side effects and work! I thought about starting on a Friday night but I also would like to enjoy the weekend with my kids and occasionally have nice food and a bit of alcohol so I dont know if thats a good time for me either! Help a girly out and let me know about your side effects that you have had and what works for you? Thanks all 😊

OP posts:
GloiredeDijon · 21/03/2026 18:37

Monday morning first thing after weigh in.
Never had any side effects except mild and transient constipation in over a year of use working my through to 15mg.

WorriedMum210721 · 22/03/2026 07:38

Thank you all! I think i might start tonight! 😁

OP posts:
MrsMiagi · 22/03/2026 07:58

Wednesday. Feel tired the next day. Used to be really cold too but that seems to have worn off now.
I dont like high suppression at weekends; jabbing on wed gives me just enough supression but i can enjoy my friday prosecco and nice food at the weekend if i want to.

Starfish1021 · 22/03/2026 08:11

Rubytoes · 21/03/2026 18:24

I received my first pen on a Tuesday so I've always jabbed then, didn't think much about it. I haven't gone above 5mg and side effects have been very mild, a bit of nausea and a change in digestive habits, but nothing that has meant I need to change plans or stop doing activities.

I'm going on holiday in a couple of weeks and I'm not sure about bringing it with me. Mainly worried about bringing it on a flight and storing it.

You can take it in your hand luggage it was really straightforward when I flew and no-one asked any questions

Gagamama2 · 22/03/2026 08:22

Inject on a Monday, worst day Wednesday (although side affects now are mild, like a mild headache or mild nausea). If I had to work in an office I would inject Thurs / Fri so I had my worst day over the weekend when I can control what I need to do.

Also worth noting when I first started, the side affects for the first two weeks were hideous. If I ate anything that was too fatty / not completely lean and fresh I would feel v nauseous and had a couple of 48 hour stints of projectile vomiting and bad diarroea. My mind also raced terribly when I was trying to get to sleep and gave me anxiety. These got much better as I stuck with it and a month in I wasn’t really having any side effects that were affecting my life so much. Just a warning in case you have anything like a holiday or business trip planned - lots of people I have spoken to said it took 2-4 weeks for their body to get used to it too.

ps it was worth sticking to, I lost 1.5 stone in 6 weeks and felt so much better

daffodilandtulip · 22/03/2026 08:23

Never really had significant side effects except for when the dose was too high. Inject Friday morning to stop me being a fat pig over the weekend. I’m a boredom eater.

Gagamama2 · 22/03/2026 08:24

ChurpyBurd · 21/03/2026 15:58

Sorry to hijack, but I am about to order my first pen...

Would regular users advise waiting until after my holiday in 2 weeks, incase of side effects, or going for it now?

On my endless healthy eating jags I have always been a 'just start now' kind of person, and now I've made the decision I'm keen to get on with it, but I don't want to potentially have headaches and constipation on my hols!

I wouldn’t risk it! Enjoy your holiday and start after. It’s only going to delay you by two weeks x

Gagamama2 · 22/03/2026 08:28

Rubytoes · 21/03/2026 18:24

I received my first pen on a Tuesday so I've always jabbed then, didn't think much about it. I haven't gone above 5mg and side effects have been very mild, a bit of nausea and a change in digestive habits, but nothing that has meant I need to change plans or stop doing activities.

I'm going on holiday in a couple of weeks and I'm not sure about bringing it with me. Mainly worried about bringing it on a flight and storing it.

I had been on MJ for 6 weeks when our 2 week holiday came round, I didn’t take it with me because was worried about flight and storing it etc. Also I react strongly to it and didn’t want any side effects ruining my holiday!

I still had appetite suppression for the whole two weeks, not as intense as when on the jab but def noticeable (and made the all inclusive aspect of the holiday a bit pointless 😂). With all the swimming and sightseeing as well I didn’t put on any weight.

sanityisamyth · 22/03/2026 08:34

Only recently started, but inject on a Friday and have some side effects on Sundays. Seems to be a two day lag for most people.

NippyNinjaCrab · 22/03/2026 08:35

@WorriedMum210721 I would just go for it. I am one of the low dose responders, when I first started I struggled to sleep like @Gagamama2 nausea and quick suppression. I am back on it now and have microdosed up until I am at 2.5mg again 😂

Edited as its not you that's off on holiday 😆

CaffeinatedMum · 22/03/2026 08:44

Monday. Tuesday evenings and Wednesday worse for side effects. I’d rather feel during the week than the weekend (two young kids so no down time).

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