4 of the Most Common Causes of Diarrhoea

By Top.me

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We have all suffered from diarrhoea at least once in our lifetime. There’s nothing worse than feeling our stomach churn and hearing it grumble, telling us to find a toilet as soon as possible.

Diarrhea can be painful, uncomfortable, and downright embarrassing. What causes it, and what should be done to ensure we limit our chances of developing it? Here are x of the most common causes of diarrhoea.

Bacterial, Viral, and Parasitic Infection

Bacteria such as Escherichia coli, Salmonella, Campylobacter, and Shigella can enter our bodies when we eat or drink contaminated food and water. Similarly, parasites, Cryptosporidium enteritis, and Giardia lamblia can cause severe stomach pain and loose stools when ingested.

A gut with a roll of toilet paper in his hand in the toilet. he is holding his stomach with one hand

Norovirus and rotavirus, often known as the ‘winter vomiting bug’ may cause the stomach and intestinal tract to become irritated, leading to diarrhoea. These types of infections rarely disappear without being treated with some form of diarrhoea medicine.

Prolonged bouts of diarrhoea can be very dangerous and lead to extreme dehydration, so seek treatment if your stools are very loose for more than two days.

Food Allergies

Our body’s immune system can sometimes make an error and identify a specific protein in a food as a threat to the body. The body reacts when this protein is ingested and triggers response symptoms such as wheezing, bloating, itching, vomiting, and diarrhoea.

The most common food allergies include nut, fish and shellfish, peanut, egg, and milk allergies. Food allergies can be very serious and sometimes result in hospitalization or even death.

Food Intolerance 

Food tolerance differs from food allergy in that it does not involve the immune system and is rarely life-threatening.

A person can develop an intolerance to foods at any point during their life. The most common foods that cause intolerance include dairy products (lactose intolerance) and wheat (which can cause gluten intolerance). After eating foods containing these products, a person may develop bloating, wind, diarrhoea, vomiting, and stomach cramps.

A doctor should be consulted if you suspect you may have a food intolerance. They may advise you to keep a food diary, detailing what you eat and when you experience unpleasant side effects.


The information leaflet inside the boxes of most medications will list diarrhoea as one of the side effects. However, certain medicines such as antibiotics, laxatives, diabetes drugs, drugs used to treat heartburn and stomach ulcers, chemotherapy medicine, and nonsteroidal anti-inflammatory drugs are more likely to cause loosening of the stools.

Antibiotics should be used sparingly as they disrupt the balance of gut flora, causing certain strains to die off and others to flourish. If the bacteria that grow in abundance are Clostridioides difficile, then a person can develop a condition known as pseudomembranous colitis, which is severely watery and sometimes bloody diarrhoea.

Tea in a transparent cup with ginger and orange around on the blue background

Laxatives are used when a person struggles to pass a stool or suffers from constipation. Laxatives work by contracting the intestinal muscles and pulling water into the gut. However, if too many are taken, these processes go into overdrive, resulting in severe stomach cramps and watery faeces.

Diarrhoea is no fun and can be extremely serious in some cases, so always seek medical assistance if it doesn’t clear up within a couple of days, the stools are pale or black, or you develop a fever.