Diarrhea That Lasts: Causes, Tests and When to Be Seen

What it involves

NIDDK defines diarrhea as passing loose, watery stools three or more times a day, or more than what is normal for you. It may be acute, persistent, or chronic, and acute diarrhea is the most common. The complications it names are dehydration and malabsorption. If you have diarrhea for less than seven days, NIDDK says a doctor typically will not need to look for the cause.

Who this is for

• Adults whose diarrhea has lasted more than a week or comes and goes for weeks
• Patients whose loose stools began after antibiotics, travel, or surgery
• Patients with diabetes, celiac disease, or a family history of bowel disease
• Patients with weight loss, bloating, or greasy stools along with diarrhea

What to expect

• Questions about how long it has lasted, what your stool looks like, and how often you go
• A review of foods, medicines, recent travel, and your family history
• An exam that checks for dehydration, belly tenderness, and changes in weight
• Tests only when they will help, such as blood work or a stool test, and a referral if more is needed

Acute, persistent, and chronic

NIDDK says acute diarrhea is more common than persistent or chronic diarrhea, and that the causes differ. The most common causes of acute diarrhea are viral gastroenteritis, food poisoning, and medicine side effects. The stomach flu guide covers the short illness. Persistent and chronic diarrhea, in NIDDK's description, comes from infections, food allergies and intolerances, digestive tract problems, abdominal surgery, and long-term use of certain medicines.

Food intolerances and carbohydrate problems

NIDDK says allergies to foods such as cow's milk, soy, cereal grains, eggs, and seafood may cause chronic diarrhea. Some people have trouble digesting certain carbohydrates. Lactose intolerance, dietary fructose intolerance, and sucrose intolerance each mean diarrhea after consuming the sugar named, and sugar alcohols in sugar-free candy and gum can cause it too. After an infection clears, trouble digesting some carbohydrates can make diarrhea last longer. The same intolerances that cause diarrhea can also cause gas and bloating, and the bloating and gas guide explains lactose, fructose, and the low-FODMAP approach MedlinePlus recommends.

Digestive conditions behind long-lasting diarrhea

NIDDK names these among the conditions that cause chronic diarrhea:

• Celiac disease, Crohn's disease, and ulcerative colitis
• Diabetes problems such as autonomic neuropathy
• Problems with the pancreas and small intestinal bacterial overgrowth
• Irritable bowel syndrome and functional diarrhea, which NIDDK calls disorders of gut-brain interaction

Medicines, surgery and antibiotics

NIDDK says antibiotics, antacids containing magnesium, and some cancer medicines can cause acute diarrhea, and that some liquid medicines contain sugar alcohols that can do the same. Long-term medicine use can cause chronic diarrhea, and antibiotics can change gut flora and raise the chance of a C. difficile infection. Surgery on the appendix, gallbladder, large intestine, liver, pancreas, or small intestine can also lead to chronic diarrhea. Tell your provider about both. Do not stop a medicine without asking.

How a provider finds the cause

NIDDK says a doctor may use your medical and family history, a physical exam, and tests. Tests it describes include stool tests to check for blood, bacteria, parasites, or signs of disease, blood tests for dehydration or underlying disorders, a hydrogen breath test for lactose, fructose, or sucrose intolerance, a trial of diet changes, and endoscopy. Blood chemistry for dehydration is explained in the basic metabolic panel guide, and an adult with new bowel changes may also review colorectal cancer screening.

Treatment and the warning signs

NIDDK says treatment of acute diarrhea is replacing lost fluids and electrolytes and, in most cases, going back to a normal diet when appetite returns. It says to talk with a doctor right away for diarrhea lasting more than two days, a high fever, six or more loose stools a day, black or bloody stools, severe belly or rectal pain, or signs of dehydration. Chronic diarrhea is treated by treating its cause, which is why the evaluation comes first. Cramping or pain with the diarrhea is covered in the abdominal pain evaluation. Bright red blood on the toilet paper has its own list of causes, and the hemorrhoids guide explains what hemorrhoids look and feel like and when to be seen.

Sources

• NIDDK — Diarrhea: Symptoms & Causes
• NIDDK — Diarrhea: Diagnosis
• NIDDK — Diarrhea: Treatment