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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.

Started MJ - Side effects

5 replies

RIRO25 · 17/02/2026 10:29

Hello lovelies!
So I have taken my second jab of 2.5mg mounjaro on Sunday morning

my first jab I just experienced nausea and tiredness for 24 hours then felt okay. This second jab has given me diarrhoea!!! It’s been 24 hours now with diarrheoa. I’m going toilet every few hours and it’s very loose. Nausea is there also, and I just want to sleep.
I am just asking will I get these symptoms everytime I take a new injection? If so, I am really not sure I want to do it if it makes me feel like this! Does it get better? Will I now have constant diarrhoea? I have take the Imodium my prescriber gave me and I’m not sure if it is working yet..
i have lost 5lbs so far so i am happy (I know it can be water weight/ diarrhoea helping too lol)

OP posts:
SilenceInside · 17/02/2026 10:33

Yes, these side effects can be common, the patient information leaflet that came with the pen will outline the possible side effects and how likely they are to occur. Side effects are most associated with starting the medication and then when moving up a dose level. Generally they settle over time and then tend not to re-occur.

You are unlikely to experience constant diarrhea and that is not something that you should try to tolerate long term.

IsItSnowing · 17/02/2026 10:50

They'll likely go away or get less as you get used to a specific dose. I'd definitely stay on the same dose for now though while your bod adjusts.

RIRO25 · 17/02/2026 11:21

Okay thank you

OP posts:
UpsideDownside · 17/02/2026 20:41

Also look at what you’re eating on the day before the injection (which will still be in your stomach on injection day) and on the day itself. Small, low fat meals will cause less side effects. Eating lasagne or spaghetti bolognese the night before an injection is a terrible idea (ask me how I know!)

LifeisLemons · 18/02/2026 12:32

You may be one of the small number of people that can’t tolerate it so you won’t know until you’ve taken at least 4 or more doses.

As the PP said, carefully review your meals so that they’re not too fatty or oily. No chips or fatty take-away foods etc. That’s a known cause of serious digestive issues after taking your dose of MJ.

Many people suffer a variety of side effects when starting MJ or when moving up a dose to the next pen but it usually only lasts for the first 1 - 3 doses and gradually subsides. I try and minimise this by micro dosing and only moving up a few mg at a time. After 6 months I’m still only taking 3.75mg from a 5mg pen.

You don’t have to move up to the next pen size after a month. You can stay on a lower dose if you feel this is better for you.

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