15 Jun 2020

It is common to have an upset tummy during and at first after critical illness. You may have stomach cramps or poo that is loose or even liquid. It will generally settle as your body slowly recovers and you get used to eating again, and as you start eating a more varied diet. Please do speak to your doctor or specialist nurse if you want more information or you are worried about it.

Why does this happen?

While you were on intensive care you will have had a lot of medication which can upset your stomach and bowels. Bowels are the lower parts of our digestive system. The stress of critical illness and the hormones that our body makes to deal with the illness, can also affect our bowels.

If you have had an operation where a large part of your bowels have been removed you may have diarrhoea. If you have a bag attached to hold your poo (called a stoma bag) you may notice your poo being very liquid. If this causes a problem for you, your medical team or dietitian can advise you on medication for this or how to change your diet a little if needed.

If you have a disease which affects your liver, pancreas or bowels, or if you had an operation on them, you may have problems with eating and digesting food. If food is not properly digested, this means that nutrients aren’t properly absorbed from your food. This type of diarrhoea is called malabsorption. It means you will also have diarrhoea with urgency to poo, especially after eating. If your poo look yellow or a pale ’clay’ colour, seem oily or glossy, floats and not easy to flush away, or unusually strong smelling, you may not be absorbing fats very well (also called steatorrhoea). Speak to your doctor or dietitian who can give you advice on medications like pancreatic enzymes and how to change your diet to help. Malabsorption can cause weight loss and can cause you to not get all the important nutrients you need (such as vitamins and minerals for your bones), so it is important to speak to your doctor or specialist nurse if you want more information or you are worried. 

Can changing what I eat help my diarrhoea?

As you recover from your critical illness and gradually increase the variety of what you eat your diarrhoea should get better. Generally, you shouldn’t need to make big changes to what you eat or drink. This is the time to try and eat enough and not limit your choices because you need food to help your recovery.

However, you might want to make small changes to help you while your stomach is upset.  The following things may help you get enough food without upsetting your tummy too much:

  • eat ‘little and often’
  • try to relax when you are eating because being nervous or anxious may make it worse
  • plan ahead when you go out so that you have little snacks to hand of foods that you know will not upset your stomach
  • cut down or stop caffeine (in coffee, tea and some fizzy drinks), alcohol and smoking because this will affect your tummy
  • if you feel that certain foods or drinks make your diarrhoea worse (like rich or fatty foods), a dietitian can advise you further so ask to be referred, especially if you are losing weight
  • it may be helpful to keep a diary for a few days of when you have diarrhoea and what foods or drinks you have had. This will help you to see if specific foods, drinks or when you are eating is causing you a problem.

Sometimes, changing what you eat for a short while may help your diarrhoea, but this is mostly if you have a bowel condition. You may hear people talking about having less roughage (such as wholemeal foods) for a while. This may be helpful for some people but shouldn’t be continued long-term without advice from a dietitian.

It is very important that you drink enough if you have an upset stomach. This is important so you don’t feel unwell because you haven’t drunk enough to replace what you are losing from having diarrhoea.

If you have had a lot of antibiotics, you might think about having products to help healthy bacteria (also called microbiome) in your stomach. There are many different products available in either drink, powder or tablet form that will give a dose of microbiome (generally called a probiotic). There are also other products or foods that help microbiome grow in the bowels (called prebiotics). They may help with diarrhoea, but if you have bloating, they may not be the best choice for now.  It you decide to try these products, do discuss this with your doctor, nurse or dietitian because there are some situations where this may not be a good idea (like if you have active bowel disease or where you have a higher risk of having an infection).

What medicines may help?

You can buy tablets from a pharmacy to help your diarrhoea.  If it is an ongoing problem, you may have been advised to take these if you go to the toilet and you have an upset stomach. These can work well but talk to your doctor or nurse if you find you need to take them often. There are also some oral rehydration fluids or powdered products available if you are finding it difficult to have enough to drink because you have severe diarrhoea. Discuss this with your doctor or nurse because these products have salts and often sugar in them and so if you have a health problem such as diabetes or with your kidneys, it might not be a good idea to have them. 


Diarrhoea can happen after a critical illness and usually gets better by itself. It can help to avoid foods that upset your tummy for a short time. You may need medicine to help, and your doctor will be able to advise you on that. As your stomach settles, you will be able to eat a varied healthy diet which will help good digestion and your bowels to work normally.

More information:

British Dietetic Association Food Fact Sheet on:

NHS UK advice on:

See ICUsteps information for more information