Metronidazole and Tinidazole toxicity

Adverse effects of metronidazole include gastrointestinal irritation epigastric distress, and abdominal cramps (it is best taken with meals), headache, paresthesias, and dark coloration of urine. Tinidazole has a similar adverse effect profile, but may be better tolerated than metronidazole. More serious toxicity includes neutropenia, dizziness, and ataxia. Drug interactions with metronidazole include a disulfiram-like reaction with ethanol and potentiation of coumarin anticoagulant effects. Safety of metronidazole and tinidazole in pregnancy and in nursing mothers has not been established. An unpleasant, metallic taste is commonly experienced with metronidazole. Other effects include oral moniliasis (yeast infection of the mouth) and, rarely, neurotoxicologic problems, such as dizziness, vertigo, and numbness or paresthesias in the peripheral nervous system. [Note: The latter are reasons for discontinuing metronidazole.]Resistance to metronidazole is not a therapeutic problem, although strains of trichomonads resistant to the drug have been reported.