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Weight loss injections/treatments
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Monjaro and dreadful side effects

43 replies

EleanorRigbyhat · 09/11/2026 05:57

I started MJ a few weeks ago. the first week was dreadful, stomach pain, indigestion, exhaustion. By the end of the week I felt a bit better so did the second jab because I had lost four pounds and wanted to keep going. I didn't have much reaction so felt encouraged. Lost more weight. Then I went on holiday and at the end of the week decided not to jab again because the food on holiday was making me feel ill on the jab.
Returned home, restarted on Wednesday. I have had the most dreadful stomach pains 24/7, feel like I have a stomach bug. I have diorreah and am sleeping really badly. I know it's the jab. It's got to the point that I am frightened to eat at all because everything i eat makes it worse. I'm drinking loads of water.

I don't think I can go on with this, it's intolerable. Has anyone else had these symptoms? My next jab is due on Wednesday and I just can't do it.

OP posts:
Shedmistress · 09/11/2026 06:10

Yes, it really plays hard and fast with the stomach, slows it right down and makes you feel quite terrible at random times. I take mine on a Friday morning and every weekend I'm having to take it easier than expected. I do find moving about when I have the stomach aches helps ease the pain.

90yomakeuproom · 09/11/2026 06:14

Yes, it’s horrendous but does work for weight loss because of it.

EleanorRigbyhat · 09/11/2026 06:16

I just don't think it can be right to be putting something in my body that makes me feel this ill and plays havoc with my whole digestive system.

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whereswilson · 09/11/2026 06:18

You've started on the trial/lowest dose?

SixAndJuliet · 09/11/2026 06:20

Speak to your GP or online pharmacist before taking another dose.

MongoosePerfume · 09/11/2026 06:34

What are you eating? I had to avoid anything greasy or fatty for a long time. Too much diary was also a trigger.

It needs to be a change all round. you can’t just eat the same as you always have.

Given it did settle for you the first time I would stick with it but really take a look at what you are eating and the triggers.

EleanorRigbyhat · 09/11/2026 06:36

Yesterday I had a bowl of soup and a scone. For dinner I had a tin of tuna with no mayonnaise, half a potato and some cottage cheese. I had a banana before I went to bed to try and settle my stomach. That was it.

Terrible stomach pains and diorreah this morning.

OP posts:
EleanorRigbyhat · 09/11/2026 06:37

whereswilson · 09/11/2026 06:18

You've started on the trial/lowest dose?

Yes

OP posts:
Shedmistress · 09/11/2026 06:40

I've had less side effects when injecting into the thigh than the stomach.

Are you stopping eating the moment you feel like you've had enough? If I don't I feel absolutely awful for the rest of the day.

OffWith · 09/11/2026 06:40

I'm sorry this is happening for you, it affects us all differently.

I'm up to 10 mg (started in June, lost 4 stone 7 pounds so far), and have only had mild constipation and a little indigestion.

Have you spoken to your prescriber? I think there might be some treaments for loose bowels.

Twiglets1 · 09/11/2026 06:42

EleanorRigbyhat · 09/11/2026 05:57

I started MJ a few weeks ago. the first week was dreadful, stomach pain, indigestion, exhaustion. By the end of the week I felt a bit better so did the second jab because I had lost four pounds and wanted to keep going. I didn't have much reaction so felt encouraged. Lost more weight. Then I went on holiday and at the end of the week decided not to jab again because the food on holiday was making me feel ill on the jab.
Returned home, restarted on Wednesday. I have had the most dreadful stomach pains 24/7, feel like I have a stomach bug. I have diorreah and am sleeping really badly. I know it's the jab. It's got to the point that I am frightened to eat at all because everything i eat makes it worse. I'm drinking loads of water.

I don't think I can go on with this, it's intolerable. Has anyone else had these symptoms? My next jab is due on Wednesday and I just can't do it.

Yes I had this reaction but on Wegovy, and had to stop taking it as a result. It just disagreed with me and made me ill.

Every time I mention this on MN, someone suggests I must have done it wrong by eating lots of fatty food or something, but this was not the case. It works well for lots of people it seems, but not for everyone. My body treated it like I had been poisoned and I never got beyond the smallest dose for this reason.

McJibes · 09/11/2026 06:48

I didn't have those symptoms and have been on it for over 2 years, so it's not inevitable and there is hope.

If I was you, I would cut down my dose to just 30 clicks, which is half, and see how I get on. I'm not a medic though, but have seen lots of people online do this and have success.

I personally started fine on 2.5mg, but didn't increase immediately to 5mg. I counted clicks to a 3mg dose, and then eased my increases up very slowly from there.

Good luck, it is an amazing medication if you can tolerate it.

EleanorRigbyhat · 09/11/2026 06:59

Twiglets1 · 09/11/2026 06:42

Yes I had this reaction but on Wegovy, and had to stop taking it as a result. It just disagreed with me and made me ill.

Every time I mention this on MN, someone suggests I must have done it wrong by eating lots of fatty food or something, but this was not the case. It works well for lots of people it seems, but not for everyone. My body treated it like I had been poisoned and I never got beyond the smallest dose for this reason.

That's how I feel, like I've poisoned myself. It's horrendous. I have sent an email to the provider.

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SilenceInside · 09/11/2026 07:22

I’m sure your provider will recommend that you stop taking it if the side effects are severe and don’t improve. Sometimes prescription medications don’t suit the individual despite working well in general.

In about 30 days all of the medication will be out of your system. Once it’s been 7 days since your injection, half of the medication will be out of your system and the side effects should reducing.

Twiglets1 · 09/11/2026 07:57

EleanorRigbyhat · 09/11/2026 06:59

That's how I feel, like I've poisoned myself. It's horrendous. I have sent an email to the provider.

There is nothing your provider can do unfortunately about the fact that the drug has bad side effects for a small number of people.

If it's any consolation, my personal experience was that the side effects went away within a few days (like you I was only on the starter dose). I hope you feel better soon.

HelenDenver · 09/11/2026 07:57

With any medication, there will be a small section of the population who gets unbearable side effects.

You may want to try Wegovy (jab or tablet) as it acts on one receptor not two (lay person understanding) and might be more tolerable for
you.

cuckoolodger · 09/11/2026 08:09

EleanorRigbyhat · 09/11/2026 06:37

Yes

So for a week or two and then restart on half the dose? Then toaster up to 3/4? I stayed on 2.5 for 2 months and only ended up on 5mg at 5th month but then had to come off as I’d lost 50lb and developed serious gall stones.

Londonnight · 09/11/2026 08:18

I was going to start a thread about this today. I have been on Mounjaro for 7 weeks 2.5mg. Week 3 I had dreadful stomach cramps and nausea. I delayed the next jab.

Past few weeks all been fine until the middle of the night last night. I now have diarrhoea, severe nausea and stomach cramps. I just feel dreadful. No fatty food, eaten within my calorie limited, drinking loads of water.

I had to come off wegovy last year due to the same symptoms plus vomiting which lasted for two weeks, I was really hopeful that mounjaro would work. I will speak to my provider, but unless these symptoms sort themselves out today I really don't think I can carry on with it.

@EleanorRigbyhat I am sorry that you are experiencing the same thing. I hope you feel better soon.

NewGrandmummy · 09/11/2026 08:22

Please, those of you suffering - listen to your bodies. Is it really worth it?

Shedmistress · 09/11/2026 08:31

NewGrandmummy · 09/11/2026 08:22

Please, those of you suffering - listen to your bodies. Is it really worth it?

Yes, I have had massive pain reduction with this and my energy levels are sky high.

The side effects are really the effects, its how it works.

Twiglets1 · 09/11/2026 08:36

Shedmistress · 09/11/2026 08:31

Yes, I have had massive pain reduction with this and my energy levels are sky high.

The side effects are really the effects, its how it works.

No it isn’t “how it works”.

Most people have minor side effects they can cope with. But a small number of people have much worse side effects and I don’t think anyone should be minimising their experience, just because they were one of the lucky ones that didn’t have very worrying symptoms of pain or extreme vomiting etc.

Shedmistress · 09/11/2026 08:43

Twiglets1 · 09/11/2026 08:36

No it isn’t “how it works”.

Most people have minor side effects they can cope with. But a small number of people have much worse side effects and I don’t think anyone should be minimising their experience, just because they were one of the lucky ones that didn’t have very worrying symptoms of pain or extreme vomiting etc.

The mechanism of action (MOA) of GLP-1 agonists is multifactorial. They primarily work in the following ways:

  1. Increased insulin production. Insulin is a hormone that helps lower blood sugar levels after meals.
  2. Decreased glucagon secretion. Glucagon is a hormone that raises blood sugar levels.
  3. Slowed gastric emptying. The rate at which food leaves the stomach is decreased, which can help prevent blood sugar spikes after eating and promote feelings of fullness.
  4. Lowers appetite. GLP-1 agonists work in the brain to reduce appetite, which can lead to less food consumption and weight loss.
  5. Increases beta cells (cells in the pancreas that make insulin).

It literally slows down the stomach emptying which is what causes the pain and the gastro symptoms.

I'm not minimising it, and indeed mentioned earlier I also get the pain.

EleanorRigbyhat · 09/11/2026 09:40

Londonnight · 09/11/2026 08:18

I was going to start a thread about this today. I have been on Mounjaro for 7 weeks 2.5mg. Week 3 I had dreadful stomach cramps and nausea. I delayed the next jab.

Past few weeks all been fine until the middle of the night last night. I now have diarrhoea, severe nausea and stomach cramps. I just feel dreadful. No fatty food, eaten within my calorie limited, drinking loads of water.

I had to come off wegovy last year due to the same symptoms plus vomiting which lasted for two weeks, I was really hopeful that mounjaro would work. I will speak to my provider, but unless these symptoms sort themselves out today I really don't think I can carry on with it.

@EleanorRigbyhat I am sorry that you are experiencing the same thing. I hope you feel better soon.

I'm so sorry, but it's some comfort I am not alone. I'm coming off this thing now and going to do old fashioned calorie counting.

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Spaniels4Eva · 09/11/2026 09:43

I'm on week 5 now and this is the 1st week where I've not known that I've taken it. Before then, I had dreadful nausea, indigestion, gallbladder rumbling and terrible stomach pains. All gone now that my body is tolerating the dose. I inject into my thighs as the GP I'm under said to - it's easier to dose yourself when you're sitting down.

The reason why I've stuck with it as that I'm diabetic and having bladder issues with the current medication that my NHS GP prescribes. I can't tell you how much better I feel because my blood sugars are so much more stable and I've felt better this week than I have done in years.

fancytoes · 09/11/2026 09:52

I’d take a break, reset with really clean healthy food and restart on a half dose (30 clicks).

I’m lucky enough to have had no side effects. I then came off for a few months. I went back on after a few indulgent weeks and needing to finish up a pen or chuck it. I had horrendous sulphur burps, sickness and diarrhoea but all over within 2 days. If I had had that for weeks I wouldn’t have carried on.

So I feel your pain but maybe give it another slow try just to be sure.