| Metronidazole: Adverse Reactions
High doses or long-term administration of metronidazole can cause peripheral neuropathy with sensory disturbances e.g. at the hands and feet. Neuropathy is often only slowly reversible or not reversible at all. Neutropenia can also develop. Metallic taste in the mouth, nausea, upper abdominal pain or headaches sometimes occur following usual therapeutic doses. Convulsions, ataxia, skin problems (skin rashes, urticaria), and vaginal candidiasis are not as common. Isolated cases of pancreatitis, cystitis, mucous colitis and hemolysis have been observed. Mutagenic effects have been observed in animal experiments; no carcinogenic effect has yet been demonstrated in humans.
Metronidazole can reinforce the effect of oral anticoagulants. A combination with cimetidine results in higher metronidazole levels. Antabuse reactions were observed when combined with alcohol. Concomitant administration of disulfiram can cause psychotic reactions.