Metronidazole does not treat chlamydia and is not a recommended treatment for chlamydia, but it may be given if symptoms of chlamydia persist after finishing a course of first-line treatments for chlamydia such as doxycycline, azithromycin, or levofloxacin. When metronidazole is given as follow up treatment for persistent symptoms of chlamydia, usually in addition to other antibiotics such erythromycin, it is there to provide treatment for other possible bacterial causes that may cause similar symptoms to chlamydia.
Infections linked with sexual activity that are usually treated with metronidazole include bacterial vaginosis, trichomoniasis, and moderate-to-severe pelvic inflammatory disease.