Symptoms

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

• Loose stools
• More-frequent bowel movements

Antibiotic-associated diarrhea is likely to begin about a week after you start taking an antibiotic. Sometimes, however, diarrhea and other symptoms don't appear until days or even weeks after you've finished antibiotic treatment.

Clostridioides difficile (formerly Clostridium difficile) infection

C. difficile is a toxin-producing bacterium that can cause a more serious antibiotic-associated diarrhea. In addition to causing loose stools and more-frequent bowel movements, C. difficile infection can cause:

• Severe diarrhea and dehydration
• Lower abdominal pain and cramping
• Low-grade fever
• Nausea
• Loss of appetite

When to see a doctor

Call your doctor right away if you have serious signs and symptoms of antibiotic-associated diarrhea. These signs and symptoms are common to a number of conditions, so your doctor might recommend tests — such as stool or blood tests — to determine the cause.