Objective: Metronidazole is an antibiotic widely used in different medical conditions such as trichomoniasis, amoebiasis, and giardiasis among others. Its use has been associated with toxicity; however, it is not well characterized. In this review, we discuss the different therapeutic uses of metronidazole and its side effects in order to aid future investigation in this field.
Materials and methods: Relevant information, original research articles, clinical trials, and reviews were collected from PubMed to know the state of the art of the different therapeutic uses of metronidazole and the reported side effects.
Results: Metronidazole was used by the first time in 1959, to treat an infection caused by Trichomonas vaginalis; subsequently, new therapeutic properties were discovered. Nowadays, Metronidazole is used to treat infections caused by Bacteroides, Fusobacteria and Clostridia, rosacea, oral and dental infections, bone and joint infections, gynecologic infections, endocarditis, septicemia, and respiratory tract infections. It also can be used to treat Crohn´s disease or even like prophylaxis, before surgical procedures. Metronidazole is well tolerated with mild to moderate side effects such as nausea, abdominal pain, and diarrhea. Nevertheless, serious neurotoxicity, optic neuropathy, peripheral neuropathy, and encephalopathy have been reported in rare cases. Their genotoxic effects observed in animal models are controversial in humans.
Conclusions: The therapeutic use of metronidazole had increased worldwide. Even though it is widely used, metronidazole has been associated with neurotoxicity and genotoxicity; however, its side effects are not well established. Conversely, its veterinary use is restricted in some countries because of its tumor association. Subsequently, further studies are needed to discover the secure use of metronidazole and describe new usages for this drug.