If the discharge from the vulva has a fishy odor, bacterial vaginosis is likely. This disease is a mixed endogenous infection caused by a decrease in Lactobacillus and an increase in Gardnerella and anaerobes in the vagina. The clinical features are a fishy odor and a marked increase in thin vaginal discharge, but there are no inflammatory changes on vaginal examination. In treatment, the first choice of anti-anaerobic drugs, mainly metronidazole, tinidazole, clindamycin. Metronidazole inhibits the growth of anaerobic bacteria and does not affect the growth of lactobacilli, which is a more ideal treatment drug. The preferred oral agent is metronidazole 400 mg twice daily for 7 days orally. For an alternative regimen, metronidazole 2g orally once daily for 3 days. Topical medications can be suppositories containing metronidazole once daily for 7 days or clindamycin ointment applied vaginally. Oral medication is similar to topical medication, with a cure rate of about 80%.