Metronidazole is available in 3 dosage forms: tablet, injection and vaginal suppository, and is usually administered for no more than 7 consecutive days and up to 10 days. Metronidazole is mainly used to treat or prevent systemic or local infections caused by anaerobic bacteria, such as those in the abdominal cavity, digestive tract, female genital system, skin and soft tissues, bones and joints. It is also an effective drug for trichomoniasis, but long-term use of metronidazole can cause gastrointestinal adverse reactions, such as nausea, vomiting, loss of appetite, bloating, diarrhea, etc. It can also cause headache and dizziness; in severe cases, it can lead to motor dysfunction and can also pass through the placenta and enter the fetal circulation rapidly. Therefore, patients are advised to use metronidazole under medical supervision. At the same time, the metabolites of metronidazole are dark red in urine, and alcohol consumption is prohibited during the medication period, as it can cause or aggravate abdominal pain, vomiting, headache and other symptoms. In addition, topical vaginal application is more effective for patients with vaginitis caused by anaerobic bacteria.