About “Metronidazole”, you should know at least these 3 points!

For medical professionals only

Evidence-based medicine, rational drug use

Metronidazole is a broad-spectrum antibacterial drug, which is of great value in the prevention and treatment of inflammation caused by various anaerobic bacterial infections[1], and is now widely used in the treatment of Helicobacter pylori Infections, hemolytic amebiasis, giardiasis, methanogenic archaea, tetanus, periodontitis and gingivitis [2].

Which situations require dose adjustment during clinical application? In what cases is it disabled? Follow Jie Xiaoyao, let’s go and have a look~

In case of these 4 special groups, the dose needs to be adjusted

Kidney damage

Oral(tablet): Patients with end-stage renal disease can slowly excrete in the urine Metronidazole and metabolites, resulting in significant accumulation of metronidazole metabolites. Monitoring for metronidazole-related adverse events is recommended.

No adjustment to the usual dose of metronidazole is required in patients with renal failure receiving intermittent peritoneal dialysis (IPD) or continuous ambulatory peritoneal dialysis (CAPD) [3].

Injection: For patients with anaerobic infection complicated with renal failure, the interval between administration should be extended from 8 hours to 12 hours[4].

Liver damage

Oral: The recommended dose for patients with severe hepatic impairment (Child-Pugh C) is 50% of the normal dose. No dose adjustment is required in patients with mild to moderate hepatic impairment. Metronidazole-related adverse events should be monitored in patients with mild to moderate hepatic impairment [3].

Injection: In patients with pre-existing liver disease, the dose should be reduced. The drug should be discontinued if ataxia or other central nervous system symptoms occur. Before repeating a course of treatment, a white blood cell count should be done [4].



Preventing Postoperative Anaerobic Infections:

Children less than 12 years old, a single dose of 20-30 mg/kg 1-2 hours before surgery; neonates <40 weeks gestational age, 10 mg/kg before surgery of a single dose.

Treatment of anaerobic infections:

For children 8 weeks to 12 years, the usual daily dose is 20-30 mg/kg, given in a single dose or divided into 7.5 mg/kg every 8 hours. Depending on the severity of the infection, the daily dose can be increased to 40 mg/kg. The duration of treatment is usually 7 days.

For children younger than 8 weeks, the daily dose is 15 mg/kg, given as a single dose or divided into 7.5 mg/kg every 12 hours. In neonates <40 weeks gestational age, metronidazole may accumulate during the first week of life, so it is best to monitor serum metronidazole concentrations several days after treatment.


The injection dose for anaerobic infection is the same as that for adults [4].


In general, dose selection should be cautious in elderly patients, who have a higher frequency of decreased hepatic, renal, or cardiac function and concomitant disease or other medications.

In elderly patients, monitoring for metronidazole-related adverse events is recommended. Decreased liver function in elderly patients can lead to increased metronidazole concentrations and may require dose adjustment of metronidazole [5-8].

Class 3 disabled


Metronidazole is contraindicated in patients with a history of hypersensitivity to metronidazole or other nitroimidazole derivatives. Metronidazole is contraindicated in the first trimester of pregnancy in patients with trichomoniasis [5-11].

Psychoactive with disulfiram

Alcoholic patients with disulfiram abstinence experience psychiatric reactions to oral metronidazole. Metronidazole is contraindicated in patients taking disulfiram within the past two weeks [5-11].

Interaction with alcohol

Oral metronidazole produces disulfiram-like reactions with alcohol, including abdominal cramps, nausea, vomiting, headache, and flushing. Stop drinking alcohol or using medicines containing propylene glycol during and for at least three days after treatment with metronidazole [5-11].

Additional Considerations

Injection: Metronidazole injection can only be given by slow intravenous infusion, either continuously or intermittently. Additives should not be added to Metronidazole Injection unless compatibility is known.

If used with the primary IV system, stop during metronidazole infusionUse the main solution. Do not use aluminum-containing tools (eg, needles, cannulas) as they can form deposits in contact with drug solutions.

Parental metronidazole injection should be visually inspected for particulate matter and discoloration prior to administration, as permitted by solution and container inspection [7-8].

Gel: Not for ophthalmic, dermal, or oral use [9-10].

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