Diarrhea

Your doctor will ask about your medical history, review the medications you take, conduct a physical exam and may order tests to determine what's causing your diarrhea. Possible tests include:

Blood test. A complete blood count test, measurement of electrolytes and kidney function tests can help indicate the severity of your diarrhea.

Stool test. Your doctor might recommend a stool test to see if a bacterium or parasite is causing your diarrhea.

Hydrogen breath test. This type of test can help your doctor determine if you have a lactose intolerance. After you drink a liquid that contains high levels of lactose, your doctor measures the amount of hydrogen in your breath at regular intervals. Breathing out too much hydrogen indicates that you aren't fully digesting and absorbing lactose.

Flexible sigmoidoscopy or colonoscopy. Using a thin, lighted tube that's inserted in your rectum, your doctor can see inside your colon. The device is also equipped with a tool that allows your doctor to take a small sample of tissue (biopsy) from your colon. Flexible sigmoidoscopy provides a view of the lower colon, while colonoscopy allows the doctor to see the entire colon.

Upper endoscopy. Doctors use a long, thin tube with a camera on the end to examine your stomach and upper small intestine. They may remove a tissue sample (biopsy) for analysis in the laboratory.

Most cases of acute diarrhea clear on their own within a couple of days without treatment. If you've tried lifestyle changes and home remedies for diarrhea without success, your doctor might recommend medications or other treatments.

Antibiotics or anti-parasitics

Antibiotics or anti-parasitic medications might help treat diarrhea caused by bacteria or parasites. If a virus is causing your diarrhea, antibiotics won't help.

Treatment to replace fluids

Your doctor likely will advise you to replace the fluids and salts. For most adults, that means drinking water with electrolytes, juice or broth. If drinking liquids upsets your stomach or causes vomiting, your doctor might recommend getting IV fluids.

Water is a good way to replace fluids, but it doesn't contain the salts and electrolytes — minerals such as sodium and potassium — that are essential for your body to function. You can help maintain your electrolyte levels by drinking fruit juices for potassium or eating soups for sodium. But certain fruit juices, such as apple juice, might make diarrhea worse.