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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.

Side effects from Mounjaro

19 replies

JHPH · 25/07/2025 11:00

I’ve been on 2.5mg now for three weeks and I’ve been advised to go up to the 5mg after week four. I know I’ve been good on the lower dose, but I’ve been told horror stories about how ill people have been taking the higher dose. I was nervous enough even going on to the injections as I have a phobia of vomiting ( sounds silly I know) any advice or support would be so appreciated.

OP posts:
threeeggsontoast · 25/07/2025 11:15

I was nervous about moving to 5mg but I was absolutely fine - no issues at all.

I use the Shotsy app which tells you roughly how much of the drug is likely to be in your system at any given time. After my fourth jab on 2.5mg, the app showed MJ had built up in my system to 3.75mg. That reassured me that moving up to 5mg wasn’t really that much.

But basically no side effects (other than constipation which I’ve had since the beginning of MJ).

JHPH · 04/08/2025 07:16

It’s the constipation that gets me! I drink over 3 litres a day, eat fruit and fibre and go to the gym 2-3 times a week. I still get badly constipated and don’t really know what else to do. I’m going up to 5mg tomorrow and I’m worried it will get even worse. Any suggestions?

OP posts:
Sallycinnamum · 04/08/2025 07:31

I have tried countless times to go above 3.75mg and my body just can't do it. Results in nausea and extreme fatigue so I have had to stay at 3mg which is fine as I am at goal weight anyway and plan to come off altogether in a few weeks.

Anecdotally, it seems the lower the weight the harder it is to tolerate higher doses so when I moved up from 2.5mg I was under 11 stone.

That said, everybody is different and from the countless threads I've read about WLI it really is a matter of giving it a go and seeing how you get on.

Divebar2021 · 04/08/2025 07:35

JHPH · 04/08/2025 07:16

It’s the constipation that gets me! I drink over 3 litres a day, eat fruit and fibre and go to the gym 2-3 times a week. I still get badly constipated and don’t really know what else to do. I’m going up to 5mg tomorrow and I’m worried it will get even worse. Any suggestions?

Well I’ve used a fibre supplement which worked ( in my case fibre gummies) but now I take a Magnesium supplement before bed. I use the one from Nutrition Geeks and have had no real problems.

Divebar2021 · 04/08/2025 07:36

JHPH · 04/08/2025 07:16

It’s the constipation that gets me! I drink over 3 litres a day, eat fruit and fibre and go to the gym 2-3 times a week. I still get badly constipated and don’t really know what else to do. I’m going up to 5mg tomorrow and I’m worried it will get even worse. Any suggestions?

For some reason my reply was hidden… I recommended a brand of Magnesium supplement which worked for me. Guess that’s a no-no then.

BabyCatFace · 04/08/2025 07:38

Divebar2021 · 04/08/2025 07:36

For some reason my reply was hidden… I recommended a brand of Magnesium supplement which worked for me. Guess that’s a no-no then.

Did you use the word güMmie? That will lead to an auto hiding!

Macaroni46 · 04/08/2025 07:42

Hi OP
I had a terrible reaction when I tried to go up to 5mg. Shivering, aching bones, vomiting, nausea, flu like symptoms, thumping headache, extreme fatigue. Was ill for 5 days. I’m sticking to 2.5mg for now.

22O725 · 04/08/2025 07:51

Honestly it would depend who advised you to move up and why. If you need to, fair enough, but I have seen far too many people saying their prescriber told them too and they had no idea they could choose to remain in 2.5mg of they wanted to. You always have the option of taking a slightly smaller dose than 5mg with your pen as well. I don’t do it as I have stayed with 2.5mg for the whole 8 months but I know lots of people do, there are many threads about ‘click counting’

Pashazade · 04/08/2025 07:52

If 2.5mg is working for you and you are getting steady weight loss then you don’t need to go up. I did 2.5 for a while, then 3.75 as a gentle step up the highest I ever went for a prolonged period was 5, tried 7.5 for two weeks and decided I couldn’t hack it. I’m now off completely but lost 4 stone this way.

TheChosenTwo · 04/08/2025 07:56

I’m 9 months in and my worst side effects have been constipation (which I’ve always suffered from even before MJ) and hair loss (had plenty to lose thank god as it’s still coming out in fistfuls).
No sickness, no nausea, no sulphur burps, no illness of any kind.
We can’t tell what kind of reaction you’ll have unfortunately but if you’ve been okay going from 0 to 2.5 I’d take that as a good sign.
If you’re doing well and losing on 2.5 without much trouble though I’d be tempted to stay on it for another month and then reassess.

ScoffingWaters2000 · 04/08/2025 07:59

Hi OP,
I moved up slowly by counting clicks as I was also worried about side effects, I did 3.75mg for 2 weeks and then up to 5mg, I do usually stay on a dose until I feel that I need to move up so not every 4 weeks and the pharmacy is fine with that, so, I was on 5mg for 8 weeks and then did the click counting and went to 6.25mg for 4 weeks, then 7.5mg which I have been on for 6 weeks, only side effect was the dreaded constipation but have solved that by eating 2 dried prunes a day with my muesli (it works for me!)
However, I decided to move to 10mg last jab as I had been plateauing for a few weeks and didn’t do the slow titrating up, I went straight from 7.5mg to 10mg (which of course is what is recommended) but by gum, nausea, dizziness and fatigue hit me for 4 days after jab day, so next jab I’ll do what I’ve been doing and take 9.75 and hopefully won’t get the effects.
Hope you find the right way for you, we all have such different stories to tell of our experiences with MJ. Good luck and let us know how it goes.

Divebar2021 · 04/08/2025 08:01

BabyCatFace · 04/08/2025 07:38

Did you use the word güMmie? That will lead to an auto hiding!

Oh I did. I didn’t know that was an issue. Thanks.

ByLemonFish · 04/08/2025 08:02

Been on 5mg for 2 weeks now, after 4 weeks on 2.5mg

Only side effect is constipation. Bought fybrogel on Saturday, hoping it helps

ihavetocookagain · 04/08/2025 08:02

Divebar2021 · 04/08/2025 07:35

Well I’ve used a fibre supplement which worked ( in my case fibre gummies) but now I take a Magnesium supplement before bed. I use the one from Nutrition Geeks and have had no real problems.

I’ve just started with the nutrition geeks magnesium x3 supplement because of constipation. Hoping it helps because the Chia seeds soaked in a glass of water, psyllium husk tabs and all bran are not hitting it! (Before anyone says I’m over fibre- ing I started with the all bran, then introduced the chia seeds, then the psyllium husk. ) I have been having to have a laxative twice a week to clear things. Even the laxatives don’t work as well. Before MJ if I needed them I’d take them at bedtime and wake up about 5-6am with my guts bubbling and moving. Now I take them at night and I may not feel anything until the following afternoon and there is much less noise and movement!

threeeggsontoast · 04/08/2025 08:29

I find the constipation is worst on jab day and the two days after so I preemptively take a laxido on jab day and then the following two days. That seems to do the trick. For me, it’s a case of not waiting till it happens but knowing it will definitely happen over those three days and sorting it out beforehand.

Everyone’s different but that works for me.

HappyWineDay · 05/08/2025 23:15

Constipation was an issue for me but I’ve found drinking LOTS of water throughout the day really helps.
I’m not sure it’s actually a side effect but more a consequence of my much changed (and reduced!) diet.

Deadringer · 05/08/2025 23:56

I have been on 5 for a while and very have had few side effects, just indigestion and constipation and they are both easily treated. I have had 4 months now of 5mg and the constipation is no longer a problem but I notice i am becoming more interested in food, especially snacky stuff so I am going to move up a dose next week. I expect a week or two of indigestion after certain foods, mainly onion, garlic and weirdly, beef, but it settles down. I have never been sick or felt nauseous, not everyone does.

ihavetocookagain · 07/08/2025 10:54

Constipation- I’m probably going to jinx myself now. I’ve been struggling with constipation all WLI time. Pre -WLI allbran and a tonne of fruit kept me regular. Now on wli I tried the all bran and some fruit- but didn’t work. Tried to add chia seeds soaked in water, didn’t work then added in psyllium husk capsules (totally 1g) didn’t work. Have now added nutrition geeks(other brands are available) magnesium glycinate 3 in 1, and it’s done nothing for my muscle relaxation,sleep (had hoped it would), or combat fatigue but I’m not constipated for the first time in weeks, and am regular!

caringcarer · 07/08/2025 11:11

JHPH · 04/08/2025 07:16

It’s the constipation that gets me! I drink over 3 litres a day, eat fruit and fibre and go to the gym 2-3 times a week. I still get badly constipated and don’t really know what else to do. I’m going up to 5mg tomorrow and I’m worried it will get even worse. Any suggestions?

Get some Fybrogel. It's a powder you add to water and it has an orange flavour. You must stir it a lot before drinking it. Also suck a few Werther's no sugar sweets. They have sorbitol in and make you need to go to poo. 3 a day would be enough. You could also have a drink of fresh orange juice with bits in.

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