What Are the Causes of Diarrhoea?

Do you spend more time sitting on the toilet than on the couch? Diarrhoea is a symptom that could be diminishing your quality of life, especially if you’ve had it for a long time. You may wonder what could be causing it.

If you suffer from chronic diarrhoea, it could be linked to a gastrointestinal problem. If it appeared recently, on the other hand, it is more likely to be a viral, bacterial or from a parasite infection. To find out what might be causing your diarrhoea and how to deal with it, keep reading our article!

Key Facts

• It is considered diarrhoea when the bowel rhythm is unusually high, with three or more liquid or pasty stools a day.  
• Diarrhoea is most often caused by intestinal infections with viruses or bacteria. It typically clears up on its own, and staying well hydrated is the best thing to do. 
• Treatment of diarrhoea with medications such as antibiotics and antiparasitic drugs should be left to your doctor’s discretion, as these could make your symptoms worse if you don’t use them properly!

The Causes of Diarrhoea: What You Need to Know

Understanding what has caused diarrhoea is essential to start managing it in the best possible way (1):

Viral diarrhoea

Viruses that affect the digestive system are typically contracted through contaminated food, drink and utensils. You can also become infected through very close contact with other infected people, just as you can catch a cold (2).

Viruses such as rotavirus and norovirus produce what is known as viral gastroenteritis, which some people call stomach flu. Diarrhoea is commonly accompanied by abdominal pain, nausea, vomiting, and fever in some cases (3). 

There is no specific treatment for the viruses that cause diarrhoea, but they can be prevented with rotavirus vaccine (4) and proper washing of hands and food (5). 

Diarrhoea caused by bacteria

Also known as bacterial gastroenteritis, this type of diarrhoea is associated with the consumption of food and drink infected with bacteria. This type of diarrhoea doesn’t spread like a cold (6).

Several types of bacteria can cause this type of infection, such as (7):

• E. Coli
• Salmonella 
• Yersinia 
• Shigella 
• Staphylococci
• Campylobacter
• Clostridium 

It is often associated with symptoms such as abdominal pain, loss of appetite, nausea, vomiting, and fever. Stools may contain mucus and/or blood.

Bacterial diarrhoea generally resolves on its own. However, you should see your physician if your diarrhoea does not improve or worsens after more than five days. 

On the other hand, very young babies should be taken to their paediatrician as soon as vomiting or diarrhoea starts.

Diarrhoea caused by parasites

Also called intestinal protozoa, parasitic diarrhoea is transmitted by the faecal-oral route. This means that particles of “poo” have somehow reached your mouth, either from poorly washed food or from eating with dirty hands.

These diarrhoeas can vary greatly from one another. For example, amebiasis causes bloody diarrhoea (8), while others like giardiasis can cause fatty diarrhoea (known as steatosis) (9). 

Diarrhoea caused by parasites often lasts for a long time, mainly affecting children in developing countries (10). While some cases may resolve on their own, most need medical treatment with antiparasitic drugs such as tinidazole, metronidazole or clotrimazole (11).

Diarrhoea caused by food intolerance

Food intolerances can lead to diarrhoea and gastrointestinal discomfort if certain components of your food are incompatible with your body (12). The most common are:

Lactose intolerance

These intolerances are much easier to identify, as they often cause diarrhoea, gas, and abdominal bloating right after eating any lactose-containing food (milk, cheese, or creams) (13). 

They are much more common in adolescents and adults, since children are more capable of breaking down the protein in milk as they must feed on it in order to survive.

Gluten intolerance

Unlike lactose intolerance, gluten intolerance or coeliac disease is due to an attack on the intestine by our immune system when it detects the presence of the gluten protein.

The symptoms start from childhood, since the body’s defences are designed to attack this protein, while destroying the villi that absorb nutrients (14).

This intolerance can cause diarrhoea, constipation, stunded growth, and learning problems in children.

Am I intolerant or allergic?

An intolerance and an allergy are different conditions, since the latter sees the food as an enemy and the immune system generates exaggerated inflammatory reactions to attack it.

The symptoms are widespread, producing skin redness, itching (in the throat and skin), nasal and eye congestion, and in some cases breathing difficulty, which is a life-threatening emergency!

Diseases that cause diarrhoea

Some diseases that affect our digestive system can lead to diarrhoea that lasts a long time, which is why it is called chronic diarrhoea. The most common are:

• Irritable bowel syndrome: This disorder of the intestine can produce episodes of diarrhoea and chronic constipation. It has no clear origin but often appears after intestinal infections or long periods of emotional stress.
• Crohn’s disease: This condition causes chronic inflammation of the intestine. It can affect any part of the digestive tract (from the mouth to the anus) and can cause intestinal bleeding that may lead to anaemia.

These diarrhoeas must be treated by a specialist, as the cause must be identified and addressed.

In some cases, probiotics can support your treatment by helping to repopulate your gut with good microorganisms (15, 16, 17).

Other diarrhoeas

We also want to highlight three very important causes of diarrhoea in this small section:

1. Antibiotic-induced diarrhoea

This type of diarrhoea is caused by the destruction of our intestinal microflora by the use of antibiotics. This exposes our intestines to the attack of harmful germs.

This is why it is essential to monitor the use of antibiotics, as they can be both a cause of diarrhoea and a treatment (if used correctly under the supervision of your physician) (18).

Probiotics could be an effective treatment to prevent the onset of this type of diarrhoea if you need to follow an antibiotic treatment or even speed up your recovery.

2. Traveller’s diarrhoea

As the name implies, this type of diarrhoea happens during travels. The cause is typically a viral, bacterial, or parasitic infection by germs from certain regions that often do not affect people who have lived there for a long time (19).

When travelling, make sure you consume food and drink from reliable sources. Don’t drink water from showers or taps and keep eating utensils clean (20). 

3. Diarrhoea in immunocompromised patients

When our defences are weakened, as can happen in diseases such as HIV/AIDS and lupus or in people with organ transplants, our intestines are much more vulnerable to diarrhoea caused by viruses, bacteria, and parasites (21). 

Your treating physician will determine the most effective treatment for these diarrhoeas, as they can be caused by different germs and have varying consequences.

Our Conclusions

Diarrhoea is merely a symptom that can have many causes. The most important thing to identify it is to identify its main characteristics such as the presence of fat, blood or mucus in the stool, and the accompanying symptoms such as fever, as well as their duration.

Most types of diarrhoea begin abruptly and disappear within a few days. However, you should see your physician for advice if your diarrhoea is prolonged or worsens over time.

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(Source of featured image: Ngamnithiporn: 140813354/ 123rf.com)