Flagyl is an intestinal antiseptic used in various bacterial and parasitic infections, gastrointestinal diseases, pelvic inflammatory disease, bacterial infections, and diseases caused by anaerobic bacteria. It works by inhibiting the growth of parasites and pathogenic bacteria. Flagyl treats diseases of the blood, brain, lungs, bones, organs, urinary tract, stomach, intestines, tooth decay and other dental diseases, leg ulcers, and pressure ulcers. Flagyl also treats parasitic infections such as amoebic dysentery.