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  8. Gut symptoms

Gut symptoms

Disclaimer: The vocabulary used on this page is written for patients rather than healthcare professionals.

Problems with digestion and gut symptoms can be cause by a COVID-19 infection.

They can include:

  • Change in taste and smell (anosmia)
  • Reduced or increased appetite (not feeling hungry or wanting to eat more food than usual)
  • Reduced food intake due to symptoms
  • Feeling full quickly after eating food
  • Not enjoying food and eating
  • Not wanting to drink fluid
  • Dry mouth
  • Swallowing problems (dysphagia) – particularly after intubation (breathing tube) in intensive care
  • Diarrhoea 
  • Gut or tummy pain
  • Indigestion 

How do these symptoms affect diet and nutrition?

Symptoms affecting the gut or digestion can make it harder to eat well and have a healthy diet. You may not feel hungry or only be able to manage certain foods. Pain, indigestion and changes in bowel habit (diarrhoea or constipation) can cause anxiety around eating. These symptoms can increase the risk of poor nutrition or undernutrition (malnutrition).

Understanding how COVID-19 may cause gut symptoms

When the COVID-19 virus enters the lungs, it sticks to special receptors (angiotensin converting enzyme 2 (ACE2) receptors) in lung epithelial cells (Kai-Yue et al., 2023). These receptors are in many parts of the body and may help explain the range of symptoms people with COVID-19 have. It may help explain loss of smell, taste and gut symptoms.

Once the virus is in the gut epithelial cells, there may be increased inflammation, damage to the gut lining and a change in the balance of gut microbes (gut dysbiosis). Drug treatments and psychological factors can also cause long-term gut problems in people recovering from COVID-19. The virus may also make pre-existing gut problems like irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD) worse. It is thought that most people with Long Covid have at least one gut or digestive symptom (Kai-Yue et al., 2023). 

Resources

Managing gut symptoms

You naturally have acid in your stomach to help begin to digest food. Sometimes this acid can hurt your gullet (oesophagus), the lining of your stomach, or the top part of your bowel (duodenum). You may have pain or discomfort in your stomach or a burning pain behind your breastbone. This is called indigestion or heartburn and can happen with COVID-19 infection. Managing indigestion after critical illness is advice is written by the BDA Critical Care Specialist Group and ICU Steps.

Diarrhoea or an upset stomach can happen as you recover from COVID-19. The BDA Critical Care Specialist Group and ICU Steps have information on managing an upset stomach or bowels [PDF] which might be helpful.

Our gut microbiome (microbes such as bacteria) can get out of balance for different reasons, including COVID-19 infection. There is interest in understanding how to get the gut microbiome to a healthy state. Probiotics may help, but the research results vary. Have a look at the BDA fact sheet to find out more about probiotics.

Swallowing problems

Managing not feeling hungry or a small appetite

Eating well during COVID-19 recovery

The Swansea Bay University Health Board therapy information pack includes ideas on how to eat and drink well and increase interest in food after COVID-19 infection. Find out more here: Covid and Long Covid recovery – therapy information pack.

This information from the BDA Critical Care Specialist Group and ICU Steps is about eating after critical illness. Some symptoms are similar to those recovering from COVID-19 infection. There is advice on how to have a balanced diet and ways to improve the amount of protein you eat. Find out more here: Nutrition at Home after Critical Illness [PDF].

Mindful eating 

Being more aware of what we eat and when we eat can encourage more positive eating behaviours and healthy eating choices. It can help you choose foods that are satisfying as well as nourishing for your body. Find out more from the BDA advice on mindful eating.

Note: The information on mindful eating may not be suitable for those with an active eating disorder. 

For more information, please see our page on underlying mechanisms of the symptoms and what we may learn from related conditions.

New evidence

COVID-19 infection may cause new gastrointestinal symptoms (Cooney et al., 2022)

What was the study about?

This very small study of 122 adults reports on acute and chronic gastrointestinal symptoms (gut and digestive symptoms) after COVID-19 infection.

What were the results?
  • 97% had more severe COVID-19 and needed hospital admission
  • 83.3% had no gastrointestinal symptoms before COVID-19. Six months after COVID-19 infection 43.8% (48 subjects) reported gastrointestinal symptoms which were new after the COVID-19 infection
  • 29.2% (14 subjects) had abdominal pain, 18.8% (9 subjects) diarrhoea, 10.4% (5 subjects) constipation, 10.4% (5 subjects) nausea and 29.2% (14 subjects) indigestion
  • 39.1% (9 subjects) had symptoms every day, 30.4% (7 subjects) a few times per week, 8.7% (2 subjects) once a week, and 21.7% (5 subjects) infrequently
What does this mean for patient care?

This study suggests that new gastrointestinal symptoms may develop in people with more severe COVID-19 infection requiring hospital admission. Some of these new symptoms may continue. This may be 'post-infection irritable bowel syndrome' (IBS).

Limitation: The number of people in the study is small. This means the results are limited and a bigger study is needed.

A new, experimental high-fibre supplement may reduce severe gut symptoms after COVID-19 infection (Wang et al., 2022). 

What was the study about?

This is a case report on one patient who had severe gut symptoms after COVID-19 infection. She was treated with a new high-fibre supplement for two months. The supplement is a new formula. It is being trialled to see if it reduces COVID-19-related gut symptoms by changing the gut microbiota (microbes such as bacteria in the gut).

What were the results?

After two months on the new fibre supplement, the patient's gut microbiome had changed. Nausea was less, and appetite had improved. Symptoms of anxiety and palpitations also got better.

What does this mean for patient care?

Changing the amount or type of fibre in the diet can change the gut microbiome. This may improve gut symptoms related to COVID-19 infection.

Limitation: This is a case report on one person. A large study is needed to establish any beneficial changes to the bacteria in the gut and improved symptoms.

Caution: The amount of fibre in your diet should always be increased slowly. This is to avoid making gut symptoms worse. You may need expert nutritional advice to help you find the right mix of dietary fibre to help with symptoms. Do not increase or change the fibre in your diet if you have been advised to follow a special diet.