Healthy Living

What Causes Diarrhea?

What Causes Diarrhea?

Diarrhea is the frequent flow of loose, watery stool through the intestines causing muscle contraction and abdominal pain. Stool follows its path through the anus and gets watery when the digestive system consumes too much fluid or gets infected with viruses, bacteria, or parasites. A loose stool contains more salt, water, and electrolytes, and thus, weighs more than solid stools. You'll know when you have diarrhea if you have had three or more bowel movements with short intervals in between. However, in breastfed babies, having loose stools is usually normal.


A persistent diarrhea can result to an excessive loss of water content in the body (dehydration). Because of dehydration, you might feel irritated and develop dry skin. Although it depends on the particular disorder, the patient affected may show the following common symptoms:

  • urge to have a bowel movement
  • a bloated belly 
  • feeling nauseous
  • vomiting
  • stomach cramps
  • thin and semi-solid stools

If you continuously have diarrhea, your symptoms may become severe. They include:

  • fever
  • decreased urination
  • rapid heart rate
  • weight loss
  • pale skin color
  • blood in stool
  • body weakness

As the infection most commonly occurs in the intestines, the doctors call it as "gastroenteritis." There are three classifications of diarrhea. They are:

  • Persistent diarrhea - if your condition lasts for 2 to 4 weeks
  • Acute diarrhea - lasts only for a short period of time
  • Chronic diarrhea - may persist longer than four weeks

If you have diarrhea and notice blood and mucus in your stool, you may have dysentery, which is an intestinal inflammation, particularly in your colon (large intestine). 

Along with the usual infectious agents, a diarrheal infection may also be a symptom of an underlying disorder such as:

Causes of Diarrhea 

Diarrhea can either be acute or chronic and each case has its own causes, symptoms, and duration. The following are some of the causes of diarrhea:

1. Water contamination

Contaminated water is the most common reason behind an infectious diarrhea. Improper fecal disposal causes the contamination of groundwater and can be easily spread among a number of people. Water must be filtered or purified before using it as a drinking water if people want to stay safe. Natural or raw water contains thousands of harmful pathogens and some of them may cause chronic diarrhea as well.

The most common disease that is spread through polluted water sources is cholera, which is a precursor of a watery diarrhea.

2. Viral gastroenteritis

One or more viruses are responsible for viral gastroenteritis. Viruses are everywhere and throughout the world, they can affect anyone at any age. Viral gastroenteritis is also called as the "stomach flu," which mostly affects people after eating contaminated food or drinks. It is a highly contagious disease that rapidly spreads from one person to another through contaminated food, water, objects, and surfaces.

3. Food Poisoning

Food poisoning is usually caused by viruses and bacteria. It is one of the most common causes of diarrhea and its symptoms include vomiting, cramping, muscle aches, etc. According to the Centers for Disease Control (CDC), 1 out of 6 Americans is affected by food poisoning every year.

4. Lactose intolerance

Lactose is a natural sugar found in all dairy products like milk, yogurt, and cheese. People who are lactose intolerant are not capable of breaking down lactose. As a result, they cannot digest the dairy products, which causes them to have diarrhea. The mechanism is simple. Their large intestine cannot produce enough lactase (an enzyme that digests lactose) to break lactose resulting in the flow of undigested lactose through the large intestine. When it reaches the large intestine, it reacts with the bacteria present there. Thus, symptoms like bloating, gas, and diarrhea happen. Lactose intolerance is also known as "lactase deficiency."

Being lactose intolerant is most common among Africans, Native Americans, and Asians. People who have lactose intolerance must avoid ingesting dairy products to stay safe or they can take medicine that contains lactase, so they can successfully digest lactose and will not experience the symptoms.

5. Colonic polyps

Colonic polyps are noncancerous growths that are found at the surface of the large intestine. The large intestine or the colon is a big hollow tube situated at the lower part of your digestive system, which stores stool and passes it towards the anus. The polyps vary in size and number. They are harmless at their primary stage and cause primary level diseases like diarrhea and irregular flow of stool, but can also be a reason of colon cancer in the later stages.

6. Necrotizing enterocolitis

Necrotizing enterocolitis happens when intestinal tissues are damaged and begin to die. It mostly affects premature babies, which causes bloody stools, diarrhea, and abdominal swelling. If these symptoms are prominent, parents must consult their baby's doctor as soon as possible. This serious condition can be life-threatening if not treated properly.

The Bottom Line

Diarrhea is an infectious disease if your condition is caused by bacteria or viruses. People can prevent the spread of this disease by maintaining proper hygiene, appropriate kitchen sanitation for the preparation of food, eating well-cooked meat, and avoiding direct contact with people who have diarrhea.

Proper sanitation and hygiene are crucial factors in the prevention of such infections. Practicing cleanliness by simple acts of washing your hands before and after meals, as well as drinking purified water can be of great help. However, if an infection further develops and if it persists, then it is always advisable to consult a doctor at the earliest. Eating a well-balanced, nutritious diet and completing your baby's immunization shots could prevent both you and and your child's chances of contracting gastrointestinal infections or diseases.

Diarrhea causes pain and suffering to the person who has it. It is also important to remember that one needs to stay hydrated if diarrhea has been persistent to avoid being dehydrated. Dehydration can also lead to fatal consequences if not treated early. Moreover, seeking medical advice is still the best option so your condition can be diagnosed right away.