Metronidazole has a powerful trichicidal effect, generally by transforming into a reduced form in the body of the worm, while damaging the DNA structure of the worm, thus impairing the function of the DNA template, for the treatment of Trichomonas vaginalis. In addition, it has a killing effect on amoebic protozoa in the intestinal tract as well as in the tissues, and is generally used for amoebic dysentery and amoebic liver abscess, with efficacy similar to that of emitin. It has the advantages of low toxicity, high efficacy, convenient oral administration and wide range of application. The usual clinical use is usually for vaginal trichomoniasis, bacterial vaginosis, and periodontitis. Topical application can be used to treat scabies, rosacea, acne are available. And it has many adverse reactions, generally common is loss of appetite, oral odor, nausea, vomiting and other adverse reactions. This drug can also cause Candida infection when applied for a long time.