Infectious Disease Compendium

Metronidazole (Flagyl®)


CrCl Formula

CrCl > 80: 125- 500 mg po/iv q 6 to 12 (usually q 12).

CrCl 80-50: 125- 500 mg po/iv q 6 to 12 (usually q 12).

CrCl 50-10: 125- 500 mg po/iv q 6 to 12 (usually q 12).

CrCl < 10: 125- 500 mg po/iv q 6 to 12 (usually q 12).

Hemodialysis: 125- 500 mg po/iv q 6 to 12 (usually q 12).

Peritoneal dialysis: 125- 500 mg po/iv q 6 to 12 (usually q 12).

Important side effects

Ataxia, dizziness, headache, peripheral neuropathy, seizures, anorexia, gi discomfort, metallic taste, n/v, disulfiram-like (antabuse) reaction with puke central.

"The syndrome frequently involves cerebellar dysfunction and more rarely involves seizures or EEG abnormalities. The metronidazole toxicity results in "characteristic reversible MRI signal abnormalities in the cerebellar dentate nuclei, dorsal brainstem, or splenium of the corpus callosum (PubMed).

Important drug interactions

Acenocoumarol, amprenavir, anisindione, carbamazepine, cholestyramine, cyclosporine, dicumarol, disulfiram, ergot derivatives, fluorouracil, fosphenytoin, lithium, phenindione, phenobarbital, phenprocoumon, phenytoin, tacrolimus, warfarin.

Rants and Screeds


Treatment of choice

Anaerobes, there ain't better. But only strict anaerobes. Treat the microaerophilic organisms with a beta lactam.

Use for

Amebiasis, anaerobic infections, Arthritis, Bacterial vaginosis, Cellulitis, Clostridium difficile-associated colitis, Clostridium infections, crohn's disease, dermatitis - seborrheic, diarrhea, Diverticulosis/itis, Dracunculus medinesis infections, Endocarditis - bacteroides, Endometritis, post-cesarean, E. histolytica, entamoeba polecki, Fasciola hepatica, fistula prophylaxis, Giardia lamblia, gynecological infections, Helicobacter pylori infections, hepatic encephalopathy, inflammatory bowel disease, Intra abdominal infections, Meningitis, ocular rosacea, Osteomyelitis, periodontal disease, pneumatosis coli, Pneumonia, pouchitis, preterm labor - prevention, rheumatoid arthritis, rosacea, Sepsis - anaerobic, surgical prophylaxis, Sweets Syndrome, tonsillitis, Trichomonas vaginalis.

Don't use for

Pregnancy. In pregnancy I mean. Not for pregnancy.


By itself. See. In a class by itself. Humor.