Flagyl Drug Interactions

Disulfiram: Psychotic reactions have been reported in patients who were using metronidazole and disulfiram concurrently.
Alcohol: Alcoholic beverages and drugs containing alcohol should not be consumed during metronidazole therapy and for at least one day afterwards because of the possibility of disulfiram-like antabuse effect reaction (flushing, vomiting, tachycardia).
Oral anticoagulant therapy (warfarin type): Potentiation of the anticoagulant effect and increased hemorrhagic risk caused by decreased hepatic catabolism. In case of coadministration, prothrombin time should be more frequently monitored and anticoagulant therapy adjusted during treatment with metronidazole.
Lithium: Plasma levels of lithium may be increased by metronidazole. Plasma concentration of lithium, creatinine and electrolytes should be monitored in patients under treatment with lithium while they receive metronidazole.
Cyclosporin: Risk of elevation of the cyclosporin serum levels. Serum cyclosporin and serum creatinine should be closely monitored when coadministration is necessary.
Phenytoin or phenobarbital: Increased elimination of metronidazole resulting in reduced plasma levels.
5-Fluorouracil: Reduced clearance of 5-fluorouracil resulting in increased toxicity of 5-fluorouracil.
Busulfan: Plasma levels of busulfan may be increased by metronidazole, which may lead to severe busulfan toxicity.
Oral Suspension: When given with alcohol, metronidazole may provoke a disulfiram-like reaction in some patients. Acute psychoses or confusion have been associated with the use of metronidazole and disulfiram together.
Metronidazole is reported to impair the metabolism or excretion of several drugs including warfarin and phenytoin, lithium, ciclosporin, and fluorouracil, with the consequent potential for an increased incidence of adverse effects. There is some evidence that phenytoin might accelerate metabolism of metronidazole. Plasma concentrations of metronidazole are decreased by Phenobarbitals, with a consequent reduction in the effectiveness of metronidazole. Cimetidine increases plasma concentration of metronidazole and might increase risk of neurological adverse effects.