Skip to content
Font Size

Diarrhea: Why It Happens and How To Treat It

When you have diarrhea, your bowel movements (stools) are loose and watery. It’s very common and although it feels bad, it's usually not serious.

It typically lasts two to three days, and if you need to treat it, there are over-the-counter medicines, which means they don't need a prescription. 

Recommended Related to Digestive Disorders

Exocrine Pancreatic Insufficiency

This condition causes problems in how your body digests food. Your pancreas doesn't make enough of the enzymes that your body needs to break down nutrients. Enzymes speed up chemical reactions in your body. The enzymes your pancreas makes move into your small intestine, where they help break down the food you eat. When you have EPI, you don't get the nutrition you need because your body can't digest and then absorb fats, starches, proteins, and some vitamins and minerals from foods. You might lose...

Read the Exocrine Pancreatic Insufficiency article > >

For many people, diarrhea strikes once or twice each year. If you have certain conditions, such as irritable bowel syndrome, it can happen more often. 

What Are the Symptoms?

You may have:

  • An urgent feeling that you need to have a bowel movement
  • Thin or loose stools
  • Watery stool
  • Nausea and vomiting
  • Bloating in your belly
  • Cramps

More serious symptoms include:

  • Blood, mucus, or undigested food in the stool
  • Weight loss
  • Fever

If you have watery stools more than three times a day and you don't drink enough fluids, you could become dehydrated. That can be dangerous if it's not treated.

What Causes Diarrhea?

Usually, diarrhea is caused by a virus that infects the gut. Some people call it "intestinal flu" or "stomach flu." 

It can also happen due to:

  • Alcohol abuse
  • Allergies to certain foods
  • Diabetes
  • Diseases of the intestines (such as Crohn's disease or ulcerative colitis)
  • Eating foods that upset the digestive system
  • Infection by bacteria (the cause of most types of food poisoning) or other organisms
  • Laxative abuse
  • Medications
  • Overactive thyroid (hyperthyroidism)
  • Radiation therapy
  • Running (Some people get “runner’s diarrhea”)
  • Some cancers
  • Surgery on your digestive system
  • Trouble absorbing some nutrients (Doctors call this “malabsorption.”)

Diarrhea may also follow constipation, especially for people who have irritable bowel syndrome.

When Should I Call My Doctor?

Call your doctor immediately if you have:

  • Blood in your diarrhea or black, tarry stools
  • A fever that is high (above 101 F) or that lasts more than 24 hours
  • Diarrhea lasting longer than 2 days
  • Nausea or vomiting that prevents you from drinking liquids to replace lost fluids
  • Severe pain in your belly or rectum
  • Diarrhea when you come back from overseas travel

Also, call your doctor right away if you have diarrhea and any of these signs of dehydration:

  • Dark urine
  • Smaller than usual amounts of urine or fewer wet diapers than usual in a baby or young child
  • Fast heart rate
  • Headaches
  • Dry skin
  • You feel irritable or confused


Today on WebMD

man holding his stomach
Get the facts on common problems.
blueberries in a palm
Best and worst foods.
woman shopping
Learn what foods to avoid.
fresh and dried plums
Will it help constipation?
top foods for probiotics
couple eating at cafe
sick child
Woman blowing bubble gum

Send yourself a link to download the app.

Loading ...

Please wait...

This feature is temporarily unavailable. Please try again later.


Now check your email account on your mobile phone to download your new app.

Woman with crohns in pain
Woman with stomach pain
diet for diverticulitis
what causes diarrhea