Causes and Risk Factors of Diarrhea.


Diarrhea is a common problem that can come on suddenly or be chronic. Some possible causes of diarrhea include food poisoning, infections, food allergies or intolerances, and medications. There are also some conditions that cause chronic diarrhea that runs through the family or, in rare cases, genetically.

You can reduce your risk of severe diarrhea by learning to keep food clean and safe both at home and when you travel.

Illustration by Brianna Gilmartin, Get Drug Information

Common causes of acute diarrhea

The most common cause of diarrhea, especially one that starts suddenly (acute diarrhea), is an infection. It can be a bacterial, viral, or parasitic disease, including :

  • Poisoned food
  • Traveler's diarrhea
  • Stomach flu

Children are at special risk for diarrhea because they tend to put objects in their mouths and may not have developed good hand washing habits.

Poisoned food

Food poisoning occurs when you eat food that is contaminated with bacteria. Bacteria build up toxins in food that will make you sick.

Food poisoning is caused by poor sanitation, improper food handling, and food storage at the wrong temperature.

  • How long the diarrhea lasts: usually less than two days
  • Caused by: toxins in food
  • When symptoms appear: Two to six hours after eating.
  • Appearance: explosive, watery
  • Other symptoms: abdominal cramps, fever, vomiting, weakness.

Traveler's diarrhea

Traveler's diarrhea is caused by eating food or drinking water contaminated with bacteria or parasites. If you have diarrhea and have recently traveled to or had raw water from a stream, river, or pond (in the United States or elsewhere), call your doctor.

  • How long does the diarrhea last: usually less than a week
  • Caused by: Food or water contaminated with bacteria, viruses, or parasites.
  • When symptoms appear: Within 12-24 hours.
  • Appearance: explosive, watery, sometimes contains mucus or blood.
  • Other symptoms: Possibly vomiting and / or fever.

Stomach flu

Stomach flu, also known as gastroenteritis, is caused by a virus, but not by the virus that causes the seasonal flu (flu). Examples of viruses that can cause stomach flu are rotavirus and norovirus . Gastroenteritis can also be caused by bacteria or parasites .

  • How long the diarrhea lasts: usually three to eight days
  • Caused by: A virus, bacteria, or parasite.
  • When symptoms appear: within two days of exposure
  • Appearance: watery
  • Other symptoms: vomiting, fever, pain.

Common causes of chronic diarrhea

Diarrhea that lasts for weeks or months can be caused by an infection, or it can be caused by an underlying medical condition or one of many other potential causes, some of which include the following:

Celiac Disease

If you have untreated celiac disease , it can be difficult for you to associate your symptoms with a specific food because your gut is damaged and you may experience symptoms all the time .

  • How long does diarrhea last? More than four weeks.
  • Caused by: gluten
  • Appearance: Large, foul-smelling, floating and greasy stools.
  • Other symptoms: involuntary weight loss, lack of energy, lack of growth in children and many other possible symptoms .

Food allergy

Symptoms of classic Ig-E food allergy appear minutes to hours after ingesting trigger foods. Allergy to any food is possible , but some foods cause the most common food allergies.

  • How long the diarrhea lasts: usually less than 24 hours
  • Started by: Specific foods
  • If symptoms appear: within two hours.
  • Appearance: Watery, may contain blood.
  • Other symptoms: hives; threw up; swelling of your face, tongue, or throat; eczema

Food intolerances

Food intolerances are caused by a lack of enzymes necessary to digest a particular food. Lactose intolerance , the inability to digest milk sugar, is the most common, but intolerance to other foods is also possible .

  • How long does diarrhea last? More than four weeks.
  • Started by: Specific foods
  • When symptoms appear: 2 to 12 hours
  • Appearance: watery, sometimes with mucus.
  • Other symptoms include shortness of breath, abdominal cramps, or pain.

Babies often show signs of protein intolerance for several months after birth. Some babies may react to dietary proteins in breast milk, while others may react to formula made from cow's milk or soy.

  • How long does diarrhea last? More than two weeks.
  • Caused by: Dairy or soy products, sometimes eggs or other proteins.
  • When symptoms appear: two hours or more.
  • Appearance: streaks of mucus or blood.
  • Other symptoms: swelling, crying, impaired development.

Inflammatory bowel disease

Inflammatory bowel disease (IBD) includes Crohn 's disease and ulcerative colitis , which are symptoms of chronic diarrhea. Both are chronic incurable diseases of the digestive tract that can be treated with surgery or medication.

  • How long does diarrhea last? More than four weeks.
  • Started by: Not associated with a specific food
  • Appearance: Blood or mucus in the stool.
  • Other symptoms: abdominal pain, fever, weight loss, growth retardation in children .

Irritable bowel syndrome

Irritable bowel syndrome (IBS) describes chronic diarrhea, constipation, and abdominal pain that are not caused by any known medical conditions .

  • How long does the diarrhea last: at least six months
  • Caused by: Not associated with a specific food, although certain foods can make symptoms worse.
  • Appearance: small and frequent stools.
  • Other symptoms: chronic bloating or bloating; constipation; pain is relieved by bowel movements

The American College of Gastroenterology recommends that anyone diagnosed with IBS and diarrhea be screened for celiac disease .


Certain medications, such as antibiotics and chemotherapy , can cause diarrhea, as can laxatives that contain magnesium. You may have a reaction to the medicine itself or to an additive, such as a fragrance.

Medications can also upset the balance of bacteria in the gut, causing stomach pain and diarrhea. Sometimes diarrhea is caused by taking too many laxatives or by long-term abuse of laxatives.

Talk to your doctor if you experience diarrhea after starting a new medicine.


There are congenital diarrheal disorders associated with certain genes. These disorders generally occur in the first months of a child's life. They are often more common in certain populations, although congenital chloride diarrhea occurs worldwide.

Several other conditions that can cause chronic diarrhea also tend to be inherited, including celiac disease, some forms of lactose intolerance, and food allergies.

Lifestyle risk factors

Diet changes, such as switching to a liquid diet, eating too much fiber, or eating spicy foods, can lead to diarrhea .

In addition to examining and possibly adjusting what you eat and ride, other habits and exposures can increase your risk of diarrhea:

Personal hygiene

The bacteria, viruses, and parasites that cause traveler's diarrhea and stomach flu are spread by contact with contaminated surfaces, food, and water. In the medical world, this is called the fecal-oral route. To reduce risk, wash your hands well after using the bathroom, changing your baby's diapers, and before eating. If you don't have access to soap and water, use an alcohol-based hand gel.

Never drink untreated water from a natural source, such as a stream. Even in developed countries, they can become infected with wild animal-borne diarrhea-causing parasites such as giardia .

When traveling to areas with a higher risk of food and water contamination, drink only bottled water and do not use ice unless it is made from bottled or purified water. Avoid raw vegetables and fruits (if they cannot be peeled), raw seafood, undercooked meats, and dairy products .

Improper food handling.

Since food poisoning is often caused by improper food handling, it is wise to follow these tips outlined by the Centers for Disease Control and Prevention :

  • Cleanliness: keep your kitchen clean; Wash dishes and cutting boards in hot, soapy water.
  • Separately: Store raw meat, seafood, poultry, and eggs separately from other foods. Use a separate cutting board for these items.
  • Cooking: Use a food thermometer to make sure the meat is cooked to an internal temperature that kills the bacteria that cause food poisoning.
  • Cooling down: make sure your fridge is below 40 degrees. Thaw frozen food in the refrigerator or microwave, not on the counter.

When to contact a healthcare provider

Diarrhea in adults usually goes away on its own, but if it persists, it can lead to dehydration (and related consequences, such as organ failure, seizures, or even death) or be a symptom of an underlying medical condition.

Seek medical attention if you have any of the following symptoms:

  • Diarrhea that lasts more than two days
  • Temperature 102 degrees Fahrenheit or higher.
  • Frequent vomiting
  • Six or more loose stools in 24 hours
  • Severe abdominal or rectal pain
  • Black, tarry stools with blood or pus.
  • Symptoms of dehydration.


Diarrhea can be especially dangerous for babies and young children because dehydration can happen quickly. It is important for your baby to feed frequently if he has diarrhea and to seek immediate medical attention if your baby or toddler has any of the following symptoms :

  • Diarrhea that lasts more than 24 hours.
  • Temperature 102 degrees For the highest
  • Severe abdominal or rectal pain
  • Stools that contain blood or pus
  • Black, tarry stools
  • Symptoms of dehydration, which in young children may differ from those in adults .

Do not give over-the-counter diarrhea medicine to infants or young children unless directed to do so by your healthcare provider. These medications can quickly build up in young children and become dangerous.

Get the word of drug information

Diarrhea can be a discomfort that will go away soon, or it can be a serious or long-term medical condition. During an attack, be sure to drink enough fluids and see your doctor if it persists.

Frequently asked questions

  • Sudden-onset diarrhea is usually caused by a bacterial, viral, or parasitic infection. Common sources of infection include food poisoning, traveler's diarrhea, and viral gastritis, also known as the stomach flu.

  • Diarrhea that lasts for weeks or months can be caused by an infection, an underlying medical condition, or certain foods. Celiac disease, food allergies or intolerances, medications, irritable bowel syndrome, or inflammatory bowel disease can cause chronic diarrhea and should be evaluated by your healthcare professional.

  • If you have diarrhea that lasts for more than two days in adults or more than 24 hours in children, you should see your doctor. Other symptoms that require medical attention for comorbid diarrhea include signs of dehydration, fever of 102 degrees Fahrenheit or higher, frequent vomiting, six or more episodes of loose stools in 24 hours, severe abdominal or rectal pain, black tarry stools. Or blood or pus in the stool.

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