Antibiotic associated diarrhea

Date Updated: 09/20/2025

Overview

Antibiotic-associated diarrhea is passing loose, watery stools three or more times a day after taking medicines called antibiotics. Antibiotics are used to treat bacterial infections.

About 1 in 5 people who take antibiotics gets antibiotic-associated diarrhea. Mild cases tend to begin shortly after taking antibiotics. Mild diarrhea usually ends after a few days on antibiotics or shortly after finishing the treatment. Diarrhea that doesn't end on its own or is more serious usually requires stopping the antibiotic. You may need to be treated with a different antibiotic.

Symptoms

For most people, antibiotic-associated diarrhea causes mild symptoms, such as:

Loose stools.
Passing loose stools three or more times a day.

Mild antibiotic-associated diarrhea may begin within hours or within a few days of starting an antibiotic.

Symptoms of more-serious diarrhea

Diarrhea that is more serious often begins several days to two months after starting the medicine.

Severe antibiotic-associated diarrhea happens when there is bacterial disease in the large intestine. Most often this is caused by a bacterium called Clostridioides difficile (klos-TRID-e-oi-deez dif-uh-SEEL). It is commonly called C. difficile or C. diff.

Symptoms may include:

Frequent or severe diarrhea.
Pain and cramping in the lower belly.
Low fever.
Nausea.
Loss of appetite.
Dehydration.

Dehydration is the loss of fluids and the minerals they carry. Symptoms of dehydration include:

Extreme thirst or dryness in the mouth.
Very little or no urine.
Dark urine.
Dizziness, lightheadedness or extreme tiredness.
Sunken cheeks or eyes.

In young children, dehydration symptoms may include:

No wet diapers for three or more hours.
No tears when crying.
A sunken soft spot in the skull.
Unusual drowsiness.

When to see a doctor

A number of conditions can cause diarrhea. Call your healthcare professional if you have:

Diarrhea that lasts more than two days.
Diarrhea with belly pain, fever or other severe symptoms.
Symptoms of dehydration.
Stools that are black, tarry or bloody.

Causes

Antibiotic-associated diarrhea may be related to:

Direct harm from an antibiotic to tissues of the large intestine.
Destruction of helpful bacteria that play a role in the digestive system.
C. difficile or other harmful bacteria that grow out of control without enough helpful bacteria to keep the harmful bacteria in check.

Antibiotics most likely to cause diarrhea

Nearly all antibiotics can cause antibiotic-associated diarrhea. Antibiotics most often involved include:

Cephalosporins.
Fluoroquinolones.
Penicillins.
Clindamycin.
Carbapenems.
Macrolides.

Risk factors

Antibiotic-associated diarrhea can occur in anyone who takes an antibiotic. Other risk factors include:

Having had antibiotic-associated diarrhea in the past.
Being an infant.
Being 65 or older.
Staying in a hospital for a long time.
Living in a nursing home.
Having a serious illness.
Taking a medicine called a proton pump inhibitor to lower stomach acids.

Complications

One of the most common complications of any type of diarrhea is extreme loss of fluids and electrolytes (dehydration). Severe dehydration can be life-threatening. Signs and symptoms include a very dry mouth, intense thirst, little or no urination, dizziness, and weakness.

Prevention

To help prevent antibiotic-associated diarrhea:

Take antibiotics only when needed. Don't use antibiotics unless your healthcare professional says you need them. Antibiotics can treat bacterial infections. But they won't help viral infections, such as colds and flu.
Wash your hands frequently. Wash your hands before and after eating or meal preparation. Wash your hands after using the toilet, after handling garbage, and when your hands are clearly dirty. If you're getting care at home or in the hospital, ask all the people who care for you to wash their hands or use an alcohol-based hand sanitizer.
Tell your healthcare professional if you've had antibiotic-associated diarrhea or C. difficile before. Having had either condition in the past increases the chance that antibiotics will cause that same reaction again. Your health professional may be able to choose a different antibiotic for you.

Diagnosis

Your healthcare professional likely will ask you questions about your symptoms, recent diet, recent use of antibiotics, and other questions about your health history. A sample of your stool may be sent to a lab for testing.

Treatment

Treatment for antibiotic-associated diarrhea depends on how bad the symptoms are.

Treatments to cope with mild antibiotic-associated diarrhea

Mild symptoms are likely to clear up within a few days after starting antibiotics or shortly after the treatment ends. You may need to switch to a different antibiotic.

Treatment of C. difficile infection

Treating C. difficile infection or a related bacterial infection requires stopping the original antibiotic. Your healthcare professional likely will prescribe antibiotics to kill the C. difficile bacteria. You also might be asked to stop taking medicines that lower stomach acids.

Additional treatments may be needed for recurring C. difficile infections. These may include medicines or a procedure to restore healthy bacteria in the colon. Severe disease may require surgery.

Self care

To manage diarrhea symptoms:

Drink enough fluids. Drink plenty of water and fluids that have electrolytes, such as broths or sports drinks or other bottled drinks with electrolytes. Oral rehydration solutions with water, electrolytes and sugar are available without a prescription. For infants and children with diarrhea, ask a healthcare professional about using an oral rehydration solution, such as Pedialyte, to replace fluids.
Ask about antidiarrheal medicines. Teenagers and adults may be able to take an antidiarrheal medicine, such as bismuth subsalicylate (Kaopectate, Pepto-Bismol, others). This generally is not recommended for children. Ask your healthcare professional before using any antidiarrheal medicine because some should not be used if you have C. difficile or other bacterial infection of the large intestine.

Some people take supplements called probiotics to restore the balance of healthy bacteria in their guts. The research is mixed on whether probiotics ease symptoms of antibiotic-associated diarrhea. Taking probiotics probably won't do harm, but people with weakened immune systems should not use probiotic supplements.

Preparing for your appointment

If you have diarrhea after taking an antibiotic, make an appointment with the healthcare professional who prescribed the antibiotic. Here's some information to help you get ready for your appointment.

What you can do

Make a list of:

Your symptoms and when they began. Include any that may not seem related to the reason you scheduled the appointment, and when they began.
Key personal information, including any major stresses or recent life changes. Include recent stays in a hospital or a nursing home.
Medicines, vitamins or supplements you take, including doses and the reasons for taking them. If you've recently taken an antibiotic, include the name and dose. If you have completed the course of antibiotic treatment, write down when you took the last dose.
Questions to ask your healthcare professional.

Some basic questions to ask include:

What tests do I need?
What is the best course of action?
Are there restrictions I should follow?
Are there foods and drinks I should avoid?
Can I take an antidiarrheal medicine?

Be sure to ask all the questions you have.

What to expect from your doctor

Your healthcare professional is likely to ask you questions, such as:

Can you describe your stools? Your health professional may have a chart with images to help you describe them.
How often do you have them?
Do you have a history of gut diseases such as ulcerative colitis or Crohn's disease?
Have you recently been around anyone with diarrhea?
Have you changed your diet recently?
Do you work in a nursing home, hospital or day care setting?
Have you recently traveled?