Generally, metronidazole tablets cannot be used externally in the vagina; it is a medication taken by mouth. Metronidazole has a special topical preparation called a metronidazole suppository, which can be used in the vagina, usually for 24 to 48 hours to absorb the drug. It usually takes about 3 days for the drug residue to be completely eliminated. Metronidazole is an anti-anaerobic antibiotic that is generally used in the treatment of anaerobic infections such as intestinal and extra-intestinal amebiasis or bacterial or trichomonas vaginal inflammation. Metronidazole tablets are generally oral medications that are absorbed only through the intestines, and do not exert much effect if they pass through the mucous membranes, and they do not dissolve easily, so topical use is not recommended. If the use of metronidazole suppositories, can be used for vaginal treatment, in the vaginal endocrine as well as the role of body temperature quickly dissolved to play a pharmacological effect. Both oral and external use, need to be applied under the guidance of a doctor.