Class Explorer · Anti-infectives
Nitroimidazoles
Reduced inside anaerobic organisms to radicals that fragment DNA. The reduction only happens in a low-oxygen environment, which is the entire basis of the spectrum.
Members
Also in this class: Tinidazole. Full pages arrive as the library grows.
Compare the members
Metronidazole
- Spectrum
- Anaerobes and protozoa
- Counselling
- No alcohol during, and 48 h after
Shared across the class
- Indications
- Anaerobic infection · C. difficile (no longer first line) · Bacterial vaginosis, trichomoniasis, giardiasis, amoebiasis · Intra-abdominal infection as part of combination therapy
- Adverse effects
- Metallic taste · Nausea · Peripheral neuropathy on prolonged use · Disulfiram-like reaction with alcohol
- Contraindications
- First trimester of pregnancy, relative · Alcohol during and for 48 hours after
- Monitoring
- Neuropathy symptoms on courses beyond a few weeks · Alcohol counselling, which has to be explicit
What makes each agent different
- Tinidazole has a longer half-life allowing shorter courses; the spectrum is essentially the same.
It has no aerobic Gram-negative activity at all, so it is a partner drug in intra-abdominal sepsis, never a solo one.
The alcohol reaction is often dismissed as folklore; it is unpleasant enough that the warning belongs on the label and in the conversation.
Last reviewed 2026-08-16 · Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed.