What Causes Diarrhea?

Diarrhea is characterized by loose, watery stools or a frequent need to have a bowel movement. It usually lasts a few days and often disappears without any treatment. Diarrhea can be acute or chronic.

Acute diarrhea occurs when the condition lasts for one to two days. You might experience diarrhea as a result of a viral or bacterial infection. Other times, it could be due to food poisoning. There’s even a condition known as traveler’s diarrhea, which happens when you have diarrhea after being exposed to bacteria or parasites while on vacation in a developing nation. Acute diarrhea is fairly common.

Chronic diarrhea refers to diarrhea that lasts for at least four weeks. It’s usually the result of an intestinal disease or disorder, such as celiac disease or Crohn’s disease.

What causes diarrhea?

You may experience diarrhea as a result of a number of conditions or circumstances. Potential causes of diarrhea include:

• a food intolerance, such as lactose intolerance
• a food allergy
• an adverse reaction to a medication
• a viral infection
• a bacterial infection
• an intestinal disease
• a parasitic infection
• gallbladder or stomach surgery

Diarrhea is also a common side effect of diarrhea.

According to the Mayo Clinic, Rotavirus is a common cause of childhood diarrhea. Bacterial infections due to Salmonella or Escherichia coli, among others, are also common.

Chronic diarrhea may be a symptom of a more serious condition such as irritable bowel syndrome or inflammatory bowel disease. Frequent and severe diarrhea could be a sign of intestinal disease or a functional bowel disorder.

What are the symptoms of diarrhea?

There are many different symptoms of diarrhea. You may experience only one of these or any combination of all of them. The symptoms depend on the cause. It’s common to feel one or more of the following:

• nausea
• abdominal pain
• cramping
• bloating
• dehydration
• a fever
• bloody stools
• a frequent urge to evacuate your bowels
• a large volume of stools

Talk to your doctor if you’re experiencing any of these symptoms.

Dehydration and diarrhea

Diarrhea can cause you to lose fluids quickly and put you at risk for dehydration. If you don’t receive treatment for diarrhea, it can have very serious effects. The symptoms of dehydration include:

• fatigue
• dry mucous membranes
• increased heart rate
• a headache
• lightheadedness
• increased thirst
• decreased urination
• dry mouth

Contact your doctor as soon as possible if you think your diarrhea is causing you to become dehydrated.

Diarrhea in babies and young children

Diarrhea is a serious condition in very young people. It can cause severe dehydration in an infant in just one day.

Call your child’s doctor or seek emergency care if you see symptoms of dehydration, such as:

• decreased urination
• dry mouth
• a headache
• fatigue
• a lack of tears when crying
• dry skin
• sunken eyes
• sunken fontanel
• sleepiness
• irritability

Seek immediate treatment if any of the following apply to your child:

• They’ve had diarrhea for 24 hours or more.
• They have a fever of 102°F or higher.
• They have stools that contain blood.
• They have stools that contain pus.
• They have stools that are black and tarry.

These are all symptoms that indicate an emergency.

How is the cause of diarrhea diagnosed?

Your doctor will complete a physical examination and consider your medical history when determining the cause of your diarrhea. They may also request laboratory tests to examine urine and blood samples.

Additional tests your doctor may order to determine the cause of diarrhea and other related conditions can include:

• fasting tests to determine whether a food intolerance or allergy is the cause
• imaging tests to check for inflammation and structural abnormalities of the intestine
• a stool culture to check for bacteria, parasites, or signs of disease
• a colonoscopy to check the entire colon for signs of intestinal disease
• a sigmoidoscopy to check the rectum and lower colon for signs of intestinal disease

A colonoscopy or sigmoidoscopy is especially helpful for determining if you have an intestinal disease if you have severe or chronic diarrhea.

What are the treatment options for diarrhea?

The treatment for diarrhea usually requires replacing lost fluids. This simply means you need to drink more water or electrolyte replacement beverages, such as sports drinks. In more serious cases, you may get fluids through intravenous therapy. If a bacterial infection is the cause of your diarrhea, your doctor may prescribe antibiotics.

Your doctor will decide your treatment based on:

• the severity of the diarrhea and related condition
• the frequency of the diarrhea and related condition
• the degree of your dehydration status
• your health
• your medical history
• your age
• your ability to tolerate different procedures or medications
• expectations for improvement of your condition

How can I prevent diarrhea?

Although diarrhea can occur for various reasons, there are actions that you can take to prevent it:

• You can avoid developing diarrhea from food poisoning by washing the cooking and food preparation areas more frequently.
• Serve food immediately after preparing it.
• Refrigerate leftovers promptly.
• Always thaw frozen food in a refrigerator.

Preventing traveler’s diarrhea

You can help prevent traveler’s diarrhea by taking the following steps when traveling to a developing nation:

• You may want to ask your doctor if you can begin an antibiotic treatment before you leave. This will greatly reduce your risk of developing traveler’s diarrhea.
• Avoid tap water, ice cubes, and fresh produce that has probably been washed with tap water while you’re on vacation.
• Drink bottled water only while on vacation.
• Eat cooked food only while on vacation.

Preventing the spread of viral or bacterial infections

If you have diarrhea that’s due to a viral or bacterial infection, you can prevent spreading the infection to others by washing your hands more frequently. When you wash your hands, use soap and wash for 20 seconds. Use hand sanitizer when washing your hands isn’t possible.