Causes

Why antibiotic-associated diarrhea occurs isn't completely understood. It's commonly thought to develop when antibacterial medications (antibiotics) upset the balance of good and bad bacteria in your gastrointestinal tract.

The antibiotics most likely to cause diarrhea

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

• Macrolides, such as clarithromycin
• Cephalosporins, such as cefdinir and cefpodoxime
• Fluoroquinolones, such as ciprofloxacin and levofloxacin
• Penicillins, such as amoxicillin and ampicillin

C. difficile infection

When antibiotics upset the balance of bacteria in your digestive system, the bacteria C. difficile can quickly grow out of control. C. difficile bacteria create toxins that attack the lining of the intestine. The antibiotics most commonly linked to C. difficile infection include clindamycin, fluoroquinolones, cephalosporins and penicillins — though taking virtually any antibiotic can put you at risk.