Metronidazole was first introduced for the treatment of trichomoniasis . Now, its therapeutics use has subsequently been expanded to include protozoal and anaerobic infections. Oral administration is recommended: rosacea, perioral dermatitis, Helicobacter pylori , Trichomonas vaginalis and Giardia lamblia infections and bacterial vaginosis.

Metronidazole given orally is absorbed almost completely. Metronidazole has limited plasma protein binding but can reach very favourable tissue distribution, including central nervous system and placenta. This drug is extensively metabolised by the liver to form 5 oxydative metabolites. The majority of this drug and metabolites are excreted in urine and feces. The half-life is 6 to 10 hours.

The recommended dose is 500 mg three time per day and an adaptation is necessary in renal insufficiency. Metronidazole is well tolerated when administered in dosages of less than 2 g per day. Some adverse reactions appear to be related to the high dosages and treatment duration. Drug interactions with alcohol, warfarin and phenytoin have been reported. Mutagenesis and cancerogenesis is only described in mouse. Resistance, both clinical and microbiological, has been described only rarely.