List of products in the National Drug Code with proprietary name . Vancomycin is an antibiotic used to treat infections. This form of vancomycin is used to treat a certain intestinal condition (colitis) caused by bacteria. This condition causes diarrhea and stomach/abdominal discomfort or pain. When vancomycin is taken by mouth, it stays in the intestines to stop the growth of certain bacteria that cause these symptoms. This antibiotic treats only bacterial infection in the intestines. It will not work for bacterial infections in any other part of the body or for viral infections (such as common cold, flu). Using any antibiotic when it is not needed can cause it to not work for future infections.