Nearly all medications have the potential to cause diarrhea as a side effect. Some medications, however, are more prone to cause diarrhea than others. For example:

• Laxatives can and are meant to produce diarrhea by drawing water into the gut and increasing the muscle contractions of the intestine.
• Antibiotics can produce diarrhea by destroying the bacteria of the gut. In some cases, antibiotics can allow a particular type of bacteria called Clostridium difficile to grow in excess. This can lead to infection with this organism, producing a severe, watery form of diarrhea called pseudomembranous colitis .
• Other drugs may be directly toxic to the digestive tract. Chemotherapy medicines, such as mycophenolate, are a common cause of diarrhea. Certain types of mesalamine also can cause diarrhea.

To prevent diarrhea related to antibiotic use, talk to your doctor about taking probiotic supplements. Continue taking these supplements for a few days after the course of antibiotics is complete.