Dealing with Mounjaro Diarrhoea 

Diarrhoea is one of the most common side effects people notice when starting Mounjaro. In clinical trials, around 16% of patients said they experienced it, making it more common than constipation.

For most people, this symptom improves with a  few lifestyle and diet changes or as your body naturally adjusts to the medication. Still, it helps to understand what’s happening in the gut so you can more effectively manage Mounjaro’s side effects. Here, we’ll give you everything you need to know. 

Why does Mounjaro cause diarrhoea 

art of how Mounjaro works involves changing the way your digestive system processes food. These changes can affect gut function, which is why some people experience side effects like diarrhoea. 

Here are the main reasons why this can happen: 

• Slowed gastric emptying – The medication slows down how quickly food leaves your stomach, signalling a change to your gut motility (how fast food passes through your digestive system). While this helps you feel fuller for longer, it can also trigger diarrhoea. 
• Increased bile acid secretion – Bile acids are natural fluids your body makes to help break down fat from food. Mounjaro can increase bile acid secretion, which can irritate the gut and cause diarrhoea. 
• Shifts in the gut microbiome – Your gut is home to trillions of tiny organisms, such as bacteria, that help with digestion. This community is called the gut microbiome. Early research suggests Mounjaro may change the balance of these microbes, which could play a role in looser stools.

Side effects usually settle down as the body adapts, but these processes help to explain why some people may experience diarrhoea while taking Mounjaro – especially when first starting treatment.

How to stop diarrhoea on Mounjaro  

If you’re experiencing diarrhoea on Mounjaro, there are steps you can take to help ease the symptoms. Simple lifestyle changes often make the biggest difference. The main areas to focus on are: 

• Dietary adjustments – choose foods that are gentle on your stomach and avoid those that can make diarrhoea worse 
• Fluid intake – try to stay hydrated and replace lost fluids to prevent dehydration.  
• Medication – in some cases, over-the-counter medicines may help, but it’s always best to check with a healthcare professional before taking anything new. At myBMI, we offer side effects treatments to help you manage symptoms.

Foods to eat when dealing with diarrhoea 

When your gut is unsettled, eating the right foods can help calm things down and give your body a chance to recover. Examples include:  

• The BRAT diet: easily digestible, low-fibre foods 
• Lean protein sources like chicken or fish 
• Probiotics to support healthy gut bacteria 
• Light, nourishing soups 

Let’s look at these in more detail.

The BRAT diet 

The BRAT diet consists of bananas, rice, applesauce, and toast. These foods are easy to digest, which makes them gentle on an irritated stomach. They can also help firm up stools and replace some of the nutrients lost during diarrhoea. 

Lean proteins 

Foods like chicken, turkey or white fish are good protein sources without added fat. Lean protein supports recovery after exercise and helps keep your energy up while still being easier on the digestive system than fatty or fried meats. 

Probiotics 

Probiotics help support a healthy gut balance. You can find them in yoghurt with live cultures, kefir or probiotic supplements. Adding probiotics may help restore balance in your gut microbiome after a spell of diarrhoea. 

Soups  

Warm, clear soups are easy to digest and can help you stay hydrated while providing some nutrients. Soups with soft vegetables or a little lean protein are ideal, while creamy or spicy soups should be avoided until symptoms ease. 

Foods to avoid whilst suffering from Mounjaro diarrhoea  

Just as some foods can help, others can make diarrhoea worse. Avoiding these while your stomach settles can make a big difference. You should try to avoid eating the following foods:

• High fibre foods 
• Spicy foods 
• Caffeine and alcohol 
• High-gas vegetables 

Here’s why: 

High fibre foods  

Normally, fibre is great for digestion. But when you have diarrhoea, too much fibre can speed up gut movement and make stools looser. 

Spicy foods  

Spices and chilli can irritate the stomach and intestines. If you’re already dealing with diarrhoea, spicy foods could worsen the problem and should be avoided until things settle down. 

Caffeine and alcohol  

Both caffeine and alcohol can upset your stomach and make diarrhoea worse. They also make it harder for your body to stay hydrated, which is especially important when you’re losing fluids. Try avoiding coffee, fizzy energy drinks and alcohol until your stomach has settled. 

High-gas vegetables 

Vegetables like broccoli, cabbage, beans and onions are harder to digest and can cause gas and bloating. These effects may worsen diarrhoea, so it’s best to avoid them until your stomach has calmed down. 

When should you be concerned about diarrhoea and see a doctor?  

Most of the time diarrhoea caused by Mounjaro is mild and settles down as your body adjusts. But sometimes it can be a sign that you need medical advice. It’s a good idea to contact your doctor if you notice: 

• Diarrhoea lasting more than a few days without improvement 
• Severe or worsening diarrhoea  
• Signs of dehydration such as dizziness, dark urine or often feeling very thirsty
• Blood in your stools or black, tarry stools 
• Severe stomach pain or cramping that doesn’t ease 

Your doctor or pharmacist may be able to suggest adjustments, check for other causes or recommend treatment to ease your symptoms.

Sources 

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