Merck Manual

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Metronidazole and Tinidazole

By

Brian J. Werth

, PharmD, University of Washington School of Pharmacy

Reviewed/Revised Jun 2022 | Modified Sep 2022
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Metronidazole is an antibiotic Overview of Antibiotics Antibiotics are drugs used to treat bacterial infections. They are not effective against viral infections and most other infections. Antibiotics either kill bacteria or stop them from reproducing... read more 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 Amebiasis Amebiasis is an infection of the large intestine and sometimes the liver and other organs that is caused by the single-celled protozoan parasite Entamoeba histolytica, an ameba. The amebas... read more , the intestinal infection giardiasis Giardiasis Giardiasis is an infection of the small intestine caused by the single-celled protozoan parasite Giardia. The main symptoms are abdominal cramping and diarrhea. People may have abdominal... read more , the vaginal infection Trichomonas vaginitis Trichomonal Vaginitis Trichomonal vaginitis is a vaginal infection caused by the protozoa Trichomonas vaginalis. Trichomonal vaginitis is usually sexually transmitted. It can cause a green or yellow discharge... read more , and the bacterial infection bacterial vaginosis Bacterial Vaginosis (BV) Bacterial vaginosis is a common condition that occurs when the balance of bacteria in the vagina (vaginal microbiome) is altered. Bacterial vaginosis causes a thin, yellow-green or gray discharge... read more . Tinidazole is a related antibiotic used primarily to treat these 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.

Use of Metronidazole or Tinidazole During Pregnancy and Breastfeeding

There are limited data on the use of tinidazole during pregnancy. However, because animal studies suggest a moderate risk of harmful effects on the fetus, pregnant women should avoid tinidazole during pregnancy.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Flagyl, Flagyl ER, Flagyl RTU, LIKMEZ, MetroCream, MetroGel, MetroGel Vaginal, MetroLotion, Noritate, NUVESSA, Nydamax, Rosadan, Rozex, Vandazole, Vitazol
Tindamax
NOTE: This is the Consumer Version. DOCTORS: VIEW PROFESSIONAL VERSION
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