What is topical metronidazole? How does it work (mechanism of action)?
Metronidazole is a synthetic (man-made) drug that is effective against certain bacteria and parasites (protozoa). The topical forms (gels, creams, and lotions) of metronidazole are used for treating vaginal infections with protozoa such as Trichomonas vaginalis, amoeba, and Giardia.
Metronidazole topical also is effective against anaerobic bacterial infections. (Anaerobic bacteria are a type of bacteria that can grow without the presence of oxygen.)
Metronidazole topical gel, cream, and lotion are available in generic forms. The brand names available for metronidazole gel/cream/lotion in the U.S. are Metrogel, Metrocream, Metrolotion, Metrogel Vaginal, Vandazole, Noritate, Rosadan, and Nuvessa.
You need a prescription from your doctor or other health care professional for this medicaiton.
What are the uses for topical metronidazole?
Metronidazole topical gel, cream, and lotion are used for treating rosacea.
Metronidazole vaginal gel is used for the treatment of bacterial vaginosis (also referred to as Hemophilus vaginitis, Gardnerella vaginitis, or nonspecific vaginitis), a bacterial infection of the vagina. It is not effective in treating another common vaginal infection, Candidal vaginosis ("yeast infection").
What are the side effects of metronidazole topical gel, cream, and lotion?
Common side effects are:
- Skin irritation
- Skin dryness
- Allergic contact dermatitis
- Burning and stinging
- Allergic reaction
- Candida vaginitis during or shortly after therapy
- Vaginal vulvar itching
- Gastrointestinal cramps or pain
- Metallic taste
Other important side effects include:
- Dark urine
- Skin rash
- Disulfiram reactions when used with alcohol. Disulfiram reaction is associated with signs and symptoms of severe flushing that may be accompanied by tachycardia and low blood pressure (hypotension).
What is the dosage for topical metronidazole?
To treat rosacea, a thin film of metronidazole gel should be rubbed on affected areas once or twice daily.
The usual dose of vaginal metronidazole gel is one applicator full (containing 37.5mg of metronidazole) intravaginally twice daily for five days. It should be applied once in the morning and once in the evening.
Which drugs or supplements interact with topical metronidazole?
Alcoholic beverages should not be consumed while being treated with metronidazole vaginal gel since this may result in:
This is the same reaction (disulfiram reaction) that occurs in alcoholics who drink alcohol while taking disulfiram (Antabuse), a drug used to discourage alcoholics from drinking alcohol.
Oral metronidazole interacts with warfarin (Coumadin), increasing the latter's blood-thinning properties. Little metronidazole is absorbed topically or from the vagina, and it is not known if the low blood levels achieved with topical or vaginal metronidazole can result in this interaction.
The vagina includes the labia, clitoris, and uterus.
Is topical metronidazole safe to use if I am pregnant or breastfeeding?
Animal studies have not demonstrated a risk to the fetus, but there are no adequate studies in pregnant women.
Orally administered metronidazole is secreted in human milk in concentrations that are similar to concentrations in the mother's blood. Although metronidazole concentration in blood after vaginal or topical administration is small, potential effects on the infant still should be considered.
What else should I know about metronidazole gel?
Metronidazolle gel, cream, and lotion are available as:
- Topical gel (0.75%, 1%)
- Cream or lotion (0.75%)
- Vaginal gel (0.75%, 1.3%)
Topical forms of metronidazole should be stored at room temperature, 15 C – 30 C (59 F – 86 F).
Metronidazole was approved by the FDA in 1963.