The main clinical indications for anaerobic infections include metronidazole, ornidazole, and morinidazole, which are administered orally when symptoms are mild and intravenously when symptoms are severe, mainly for gastrointestinal infections or pelvic inflammatory disease in female patients. Metronidazole is relatively inexpensive in clinical practice, and gastrointestinal symptoms such as nausea and even vomiting are more common after use. Ornidazole and morinidazole have relatively few gastrointestinal symptoms such as nausea and even vomiting after use.