Some antidepressants may increase the risk for hard-to-treat gastrointestinal infections caused by bacteria called C. diff. Mirtazepine (Remeron), fluoxetine (Prozac) and nortriptyline (Pamelor) were all linked to a greater likelihood of Clostridium difficile diarrhea. People with depression are also more susceptible to this infection.
[BMC Medicine, online May 6, 2013]