• Diseases&Conditions
• Procedures & Tests
• Injuries & Symptoms
• Special Topics
• Nutrition

Diarrhea caused by antibiotics is usually the result of an infection from a specific bacteria—called "C diff" —that has a selective advantage in growth despite antibiotics. A variety of other symptoms may occur in the colon and can be serious enough to require surgical treatment.

What is going on in the body?

Diarrhea is a possible side effect of antibiotic treatment whether it is taken by vein or by mouth. Most antibiotics can cause diarrhea. The major reason is the growth of a bacteria called Clostridium difficile or C. diff. This is a specific type of bacteria that gains a selective advantage over normal bacteria in the bowel when people take antibiotics.

The infection with C. diff itself causes the "antibiotic" diarrhea. The infection may lead to severe inflammation and colitis in the colon..

What are the signs and symptoms of the condition?

Symptoms may include:

• diarrhea which can be severe
• abdominal distress or cramping
• nausea and vomiting
• fever

Severe C. diff infections may cause:

• blood in the stool
• tenderness when the abdomen is touched
• serious injury to the colon that can result in perforation and require surgery
• paralysis of the colon called "toxic megacolon."

What are the causes and risks of the condition?

Diarrhea due to infection with C. diff is different than other diarrheas.. People normally have many bacteria in the bowel without problems. When an antibiotic is given, it may kill most of the "good" bacteria in the bowel. But bacteria called C. difficile are usually not killed and in fact outgrow the other bacteria.

C. difficile produces a toxin that affects the lining of the intestine and causes inflammation and diarrhea. Diarrhea may occur during antibiotic use or even weeks after antibiotics are discontinued. Stopping the antibiotic usually won't stop this type of diarrhea.

The diarrhea can lead to dehydration and fluid imbalances. With severe diarrhea due to C. difficile, other complications are possible. These include enlargement of the bowel or the formation of a hole in the bowel. Either can be life threatening and may require surgery.

What can be done to prevent the condition?

The best prevention is to avoid antibiotics when they are not necessary. Proper hand washing when caring for people with diarrhea is important.

Also gowning when in contact and disposal of gowns before making contact with others is essential. C. diff can be transferred to uninfected people from contamination of hands or clothing.

How is the condition diagnosed?

A medical history and exam help make the diagnosis. A history of diarrhea and recent or current antibiotic use is an important clue. Cases caused by C. diff infection can be confirmed by testing the stool for the bacteria's toxin.

What are the long-term effects of the condition?

Most people recover without any long-term effects. Diarrhea that is very heavy or that lasts a long time can lead to salt imbalances and dehydration.

Rarely, a hole forms in the bowel, or the bowel becomes enlarged. This can lead to severe infection and even death. These people may require a colectomy and will have to have an ileostomy, that is, a bag to collect their stool.

What are the risks to others?

This infection can be passed from one person to another if strict handwashing and gowning practice is not enforced.

What are the treatments for the condition?

The first step is to stop taking the responsible antibiotic. IV fluids may be used to treat dehydration and fluid imbalances.

Two antibiotics are commonly used to kill C. diff. They are metronidazole (i.e., Flagyl) and vancomycin.

If fluid loss from diarrhea is significant, if abdominal pain is severe, if fever becomes prominent, the patient with antibiotic diarrhea from C diff should be admitted to the hospital for treatment which may include surgery.

What are the side effects of the treatments?

Metronidazole can cause stomach upset, nausea, and a metallic taste in the mouth. Vancomycin taken by mouth causes few side effects, if any. People should not drink alcohol while taking metronidazole because the combination may cause severe abdominal distress and vomiting.

What happens after treatment for the condition?

Most people get better as soon as the antibiotic is stopped, and others improve with fluids and either metronidazole or vancomycin.

How is the condition monitored?

A physician will monitor the patient for fluid deficits and colitis. The stool test for the C. difficile toxin may be used to monitor diarrhea from infection. Any new or worsening symptoms should be reported to the healthcare provider, especially if they are related to abdominal pain.