Nitroimidazole antimicrobials
Nitroimidazoles are medicines that kill certain bacteria that live without oxygen, and some parasites. They are used to treat infections such as some gut, pelvic, dental and skin infections, and infections caused by parasites such as amoeba and trichomonas. Examples include metronidazole, tinidazole and ornidazole. They do not work on viruses, colds or flu, and they should not be taken with alcohol.
Pharmacist review in progress. This page is based on the sources listed below and is being checked by our registered pharmacist.
How do Nitroimidazole antimicrobials work?
Inside bacteria and parasites that live without oxygen, the medicine is changed into a form that damages their DNA, and they die. Ordinary body cells and bacteria that use oxygen are largely unaffected.
Active ingredients of this type
These active ingredients belong to Nitroimidazole antimicrobials. They are listed A to Z.
- Metronidazole: Metronidazole is a nitroimidazole medicine used to treat certain infections caused by bacteria that live without oxygen and by some parasites.
Common questions
Why must alcohol be avoided with nitroimidazoles?
Alcohol with metronidazole can cause sickness, stomach pain, hot flushes and a racing heartbeat. The NHS advises avoiding alcohol during treatment and for 2 days afterwards, and the US label says 3 days. Ask your pharmacist if unsure, and avoid alcohol-containing syrups and mouthwashes.
Why do these medicines taste metallic?
A metallic or bitter taste in the mouth is a common, harmless side effect of metronidazole and similar medicines, and goes away after the course. Tell your doctor if you also have numbness, tingling, fits or confusion, which need prompt attention.
Sources
- Metronidazole tablets: prescribing information (DailyMed label, updated January 2026). DailyMed, US National Library of Medicine
- Side effects of metronidazole. NHS (UK)
- ATC/DDD Index: J01XD Imidazole derivatives. WHO Collaborating Centre for Drug Statistics Methodology