Metronidazole is an antibiotic used to treat many conditions caused by anaerobic bacteria or protozoans. Some bacterial infections include septicemia, endocarditis, and infections involving bone, joint, and the lower respiratory tract.
For these bacterial infections, metronidazole is administered intravenously. Metronidazole is also used to treat rosacea, for which it’s administered topically.
Finally, metronidazole is also used orally or topically to treat bacterial vaginosis; and it is used to treat protozoal infections, including amebiasis, trichomoniasis, and giardiasis, for which it’s given orally.
Now, once administered, metronidazole gets inside anaerobic bacteria and protozoans, and produces free radicals, which damage the pathogen’s DNA.
Without the DNA as a template, the pathogen can’t synthesize any more nucleic acids like DNA or mRNA, and will ultimately die.
Common side effects of metronidazole include headache, dizziness, and gastrointestinal disturbances like abdominal cramps, anorexia, nausea, vomiting, and diarrhea.
In addition, metronidazole may allow certain bacteria like Clostridioides difficile to survive and invade the gastrointestinal tract, rarely but potentially leading to Clostridioides difficile infection or CDI for short.
In high doses, or with prolonged treatment, it can cause a reddish urine, and neurological effects, such as seizures, confusion, and peripheral neuropathy can be seen; as well as aseptic meningitis, when given intravenously.