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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:
mollibu · 21/03/2026 14:48

I do a Friday morning because I know I’ll be more tempted by nice food on a weekend than I would a weekday being at work. Works well for me!

No side affects thankfully!

userohhuser · 21/03/2026 14:51

Inject on Monday, worse day Wednesday

holjam · 21/03/2026 14:53

Monday morning so that I can enjoy my weekends. I don’t have side effects anymore but when I did have nausea the worst day would be Tuesday.

SilenceInside · 21/03/2026 15:01

Friday morning, for highest appetite suppression over the weekend, and just in case of side effects and work. But that’s not been an issue for me.

You can drink alcohol, it’s not common to have an issue with that. You can also have nice food, you likely just won’t eat as much of it as you might have before. And your idea of nice food might change a bit.

cupfinalchaos · 21/03/2026 15:07

userohhuser · 21/03/2026 14:51

Inject on Monday, worse day Wednesday

Me too and Wednesdays are the worst. Headache and nausea. I loved my coffee it now can’t even smell it. Hey ho, one holiday to get through then I’m tapering off.

Wickedlittledancer · 21/03/2026 15:09

I’ve never had side effects, 80 percent of people don’t. I inject on a sat morning as I’m usually home then and not stressed with work.

HeidiLite · 21/03/2026 15:23

thursday evening to have most suppression over the weekend, as this is the time I snack the most. But I haven't had any sife effects really.

Willowy2 · 21/03/2026 15:24

When I first started I used to do Wednesday evening before bed but never had side effects. I'm on maintenance now and just so it whenever as I know it doesn't affect me negatively.

PearlsTeapot · 21/03/2026 15:24

It usually wears off around day 6/7. With that in mind, I inject Sunday evenings so that I can eat more on weekends. That’s deliberate as I calorie cycle so eat more on those two days and eat really carefully weekdays.

My only side effect is constipation which I’ve had all year, nothing else.

VioletandMauve · 21/03/2026 15:43

I inject on a Sunday morning and don’t have any side effects on any of the days. When I first started 5 months ago I did get a little bit of tiredness on the Monday but that was all.

Maydaymarion · 21/03/2026 15:48

At first I would inject on Friday night as next day would be headache and tired bit nauseous, generally off, now in maintenance it doesn't affect me that way, but I still get constipation if I'm not careful with fibre, so every day have chia and plenty of fruit.

user18 · 21/03/2026 15:51

thursday but just because thats when it arrived. I felt a bit queasy the first day and in general Im more tired in the evenings but I suspect thats partly due to less food. I also feel really lightheaded after one glass of wine so I'm now a cheap date.

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!

MoneyJo · 21/03/2026 16:01

Thursday night so it kicks in by Friday morning. 3 jabs in and no side effects so far.

etchedinstone · 21/03/2026 16:03

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’d just start straight away. I’m like you and believe in just throwing myself into things. I started the week before Christmas (2024) and it just stopped me overeating over the holiday period.

InfoSecInTheCity · 21/03/2026 16:03

Thursday because that’s the day I got it the first time. I’ve never had any side effects other than feeling cold, but that is probably compounded by having lost a whole persons worth of insulation (10 stone). I was eating healthy before I started the MJ because I’d been diagnosed with diabetes and was trying to control my sugar levels with insulin, metformin and a very strict low carb diet. It wasn’t working so they added in the Mounjaro which was miraculous! But that does mean I was prepared for slowed digestion and didn’t have a gut full of stuff that could make me feel ill.

HeidiLite · 21/03/2026 16:06

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!

that's an interesting dilemma of course. I know people who take a break over the holidays, but personally I had a holiday just a couple of weeks after I started and continued with the drug. Had still very strong suppression, but I enjoyed the holiday just the same. It's not like being around food and drinks and denying yourself the pleasure - I simply didn't feel like over-eating. And it was lovely to get home having lost weight, not gained.

PearlsTeapot · 21/03/2026 16:54

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’d wait. I never had any side effects except constipation (pretty badly from day one) but I’d be worried about it and it would effect my holiday.

However I have health anxiety! And 80% of people have no side effects so if you’re a chilled person just go for it.

Fishingboatbobbingnight · 21/03/2026 17:18

Been on it for 2 years next month had one episode constipation 19 months ago.. went all the way up and back down again.. maintained on 5mg for 13 months and lost 9 st. (Size 22 to size 8) . The only thing I had to do was have a tummy tuck because of so much loose skin (best decision I’ve ever made) .. I have 15 friends I know of who are on it and none have had any side effects.. they are pretty rare ..

TheSlimmingPumpkin · 21/03/2026 17:20

Monday is Mounjarno day. No side effects. Jab about an hour before bedtime.

Starfish1021 · 21/03/2026 17:28

I have moved it around as I was Friday for ages. Now Monday as I prefer to have a bit of appetite at the weekend. I get tired and cold about 24 hours after my jab. Its so weird was worse on a higher dose. I would just get started to be honest.

Nevertriedcaviar · 21/03/2026 17:33

I'm glad to hear that 80% of people don't get side effects. I did my first dose of Wegovy this morning. No side effects so far. I'll be interested to see how it works out. I'm not particularly hungry though.

Maydaymarion · 21/03/2026 18:11

There's side effects and the there's side effects though, I responded instantly to 2.5, and reading on here and anecdotally if you respond really quickly you tend to have side effects, usually pretty mild, but enough to maybe make you feel a bit bleurgh, or tired, I'm glad I did because obviously never having to go up the doses = cheap, but I think no one knows until they take it how they'll respond.

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.

TheSlimmingPumpkin · 21/03/2026 18:32

Don’t worry about @Rubytoes just buy a Frio wallet off Amazon and take pen onboard flight. No one bats an eyelid. I have taken pens to India, Canada and all over Europe.