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Metronidazole and Tinidazole


Brian J. Werth

, PharmD, University of Washington School of Pharmacy

Last full review/revision Jul 2020| Content last modified Jul 2020
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Metronidazole is an antibiotic used to treat pelvic, abdominal, soft-tissue, gum, and tooth infections and abscesses in the lungs or brain. It is also the preferred drug for certain protozoal infections, such as amebiasis, the intestinal infection giardiasis, the vaginal infection Trichomonas vaginitis, and the bacterial infection bacterial vaginosis. Tinidazole is a related antibiotic used primarily to treat those same protozoal infections and bacterial vaginosis.

Metronidazole works by disrupting the production of genetic material by bacteria. As a result, the bacteria die. Tinidazole works in a similar way.

Metronidazole is usually taken by mouth but can be given intravenously. Tinidazole is taken by mouth.

Metronidazole and tinidazole can interfere with alcohol metabolism and can cause unpleasant side effects similar to those of a hangover including nausea, vomiting, flushing, and headache. Alcohol should be avoided while taking metronidazole or tinidazole and for 3 days after the last dose.


Metronidazole and Tinidazole

Common Uses

Some Side Effects

For metronidazole and tinidazole: Infections caused by certain protozoa such Trichomonas vaginalisEntamoeba histolytica, and Giardia lamblia, and for bacterial vaginosis

For metronidazole: Pelvic and abdominal bacterial infections

Nausea, vomiting*



Metallic taste

Numbness and tingling in the hands and feet (peripheral neuropathy)

Dark urine

* These side effects occur especially if the drugs are taken with alcohol.

Use of Metronidazole or Tinidazole During Pregnancy and Breastfeeding

Metronidazole and tinidazole should be avoided during the 1st trimester of pregnancy because birth defects are possible. (See also Drug Use During Pregnancy.)

Women who are breastfeeding should not take metronidazole or tinidazole. (See also Drug Use During Breastfeeding.)

Drugs Mentioned In This Article

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Actinomycosis is a chronic infection caused mainly by the bacteria Actinomyces israelii. These are anaerobic bacteria, meaning they can thrive without oxygen. Actinomyces israelii are normally found on tooth enamel, gums, tonsils, and membranes lining the intestines and vagina. Under which of the following conditions does an actinomycosis infection typically develop?
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