metronidazole, Flagyl (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

DRUG INTERACTIONS: Alcohol should be avoided because metronidazole and alcohol together can cause severe nausea, vomiting, cramps, flushing, and headache.

Metronidazole can increase the blood thinning effects of warfarin (Coumadin) and increase the risk of bleeding probably by reducing the break down of warfarin.

Cimetidine (Tagamet) increases blood levels of metronidazole while cholestyramine reduces blood levels of metronidazole by reducing its absorption.

Metronidazole should not be combined with amprenavir (Agenerase) for treating human immunodeficiency disease (infection with HIV) because amprenavir contains propylene glycol. Metronidazole blocks the breakdown of propylene glycol in the liver leading to accumulation of propylene glycol in blood. Accumulation of propylene glycol could cause seizures, increased heart rate, and lead to kidney failure.

Metronidazole increases the blood levels of carbamazepine (Tegretol, Tegretol XR , Equetro, Carbatrol), lithium (Eskalith, Lithobid) and cyclosporine though unknown mechanisms. Serious reactions may occur if these drugs are taken with metronidazole.

PREGNANCY: Metronidazole is not used in early pregnancy because of potential adverse effects on the fetus.

NURSING MOTHERS: Metronidazole is excreted in breast milk. Nursing mothers, because of potential adverse effects on the newborn, should not use metronidazole.

SIDE EFFECTS: Metronidazole is a valuable antibiotic and is generally well tolerated with appropriate use. Minor side effects include nausea, headaches, loss of appetite, a metallic taste, and rarely a rash. Serious side effects of metronidazole are rare. Serious side effects include seizures and damage of nerves resulting in numbness and tingling of extremities (peripheral neuropathy), encephalopathy, and aseptic meningitis. Metronidazole should be stopped if these symptoms appear.

Additional resources from WebMD Boots UK on Metronidazole

Reference: FDA Prescribing Information


Last Editorial Review: 1/4/2011



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