Diarrhea is a common side effect of antibiotics; it may prolong hospital stay, increase the risk of other infections, develop into more serious forms of disease, and lead to premature discontinuation of the needed antibiotic. The purpose of this study is to examine the safety and effectiveness of a capsule containing Lactobacillus rhamnosus GG in the prevention of diarrhea associated with antibiotic use.

Inclusion Criteria:

• Participants (male or female inpatients) 18 to 64 years of age who are prescribed antibiotics (single or multiple antibiotics, oral or intravenous) will be recruited from the Fargo VAMC Primary Care Clinic area.
• Participants must be able to swallow a capsule.

Exclusion Criteria:

• Exclusion criteria include diarrhea on admission or within the preceding week
• Reported recurrent diarrhea
• Antibiotics in the past four weeks
• Significant underlying conditions (e.g. diabetes, structural cardiac defects including valvular defects, history of infective endocarditis, poor cardiac function, immunosuppression, impaired gut integrity, moderate or serious intestinal disorders, malignancies, pancreatitis, indwelling catheters, recent surgery, recent prolonged hospitalization)
• Previous bowel surgery
• Nutritional restrictions that preclude participation
• Hypersensitivity to penicillin G, ampicillin, or erythromycin
• Persons who have been prescribed their antibiotic for a duration longer than 3 weeks