Metronidazole vs. Miconazole

• Metronidazole and miconazole are both used to treat different types of vaginal infections. Metronidazole is used to treat bacterial vaginosis and trichomonas vaginal infections, and miconazole is used to treat vaginal yeast infections.
• Metronidazole is also used to treat parasitic infections including Giardia infections of the small intestine, amebic liver abscess, and amebic dysentery; carriers of trichomonas who do not have symptoms of infection; abscesses in the liver, pelvis, abdomen, and brain caused by susceptible anaerobic bacteria; C. difficile diarrhea; stomach or intestinal ulcers caused by Helicobacter pylori; and acne rosacea (topical gel form).
• Miconazole is also used the skin to treat fungal infections.
• Metronidazole and miconazole belong to different drug classes. Metronidazole is an antibiotic and miconazole is an antifungal.
• Brand names for metronidazole include Flagyl, Flagyl ER, Metrogel, and Noritate.
• Brand names for Miconazole include Monistat, M-Zole, and Micatin.
• Side effects of metronidazole and miconazole that are similar include skin rash.
• Side effects of metronidazole that are different from miconazole include nausea, headaches, loss of appetite, abdominal cramps, vomiting, diarrhea, dry mouth, dark-colored urine, metallic taste in mouth, weight loss, dizziness, constipation, furry tongue, stuffy nose, flushing, and vaginal dryness.
• Side effects of miconazole that are different from metronidazole include vaginal or skin irritation, burning, and itching.

Metronidazole is an antibiotic effective against anaerobic bacteria and certain parasites. Metronidazole is used to treat parasitic infections including Giardia infections of the small intestine, amebic liver abscess, and amebic dysentery (infection of the colon causing bloody diarrhea), bacterial vaginosis, trichomonas vaginal infections, carriers of trichomonas (both sexual partners) who do not have symptoms of infection; abscesses in the liver, pelvis, abdomen, and brain caused by susceptible anaerobic bacteria; C. difficile diarrhea; stomach or intestinal ulcers caused by Helicobacter pylori (H. pylori); acne rosacea (topical gel form); and bacterial vaginosis (vaginal gel form).

Miconazole is an anti-fungal medication related to fluconazole (Diflucan), itraconazole (Sporanox), ketoconazole (Nizoral), and clotrimazole (Lotrimin, Mycelex). It is used either on the skin or in the vagina for fungal infections.

Metronidazole

Flagyl is a useful antibiotic and is generally well tolerated with appropriate use. The most common and minor side effects include:

• Nausea
• Headaches
• Loss of appetite
• A metallic taste
• Rarely a rash
• Abdominal cramps
• Vomiting
• Diarrhea
• Dry mouth
• Dark-colored urine
• Metallic taste in mouth
• Weight loss (anorexia)
• Dizziness
• Constipation
• Furry tongue
• Rash
• Nasal congestion
• Flushing
• Vaginal dryness

Side effects that are uncomfortable, but may become serious include:

• Brain disease
• Fevers
• Mouth sores
• Pain with urination
• Prickling or tingling sensations that may become permanent
• Cystitis
• Pelvic pain or pressure
• Decrease of libido
• Proctitis
• Stomitis
• Glossitis

Serious side effects of Flagyl are rare and the drug should be stopped if these symptoms appear:

• Seizures
• Damage of nerves resulting in numbness and tingling of extremities
• Peripheral neuropathy
• Encephalopathy
• Aseptic meningitis
• Asceptic meningitis
• Colon cancer in people with Crohn's disease

Miconazole

Irritation, burning, rash and itching have been reported by patients using topical or vaginal miconazole.

Metronidazole

• Metronidazole may be taken orally with or without food.
• In the hospital, metronidazole can be administered intravenously to treat serious infections.
• The liver is primarily responsible for eliminating metronidazole from the body, and doses may need to be reduced in patients with liver disease and abnormal liver function.

Miconazole

Miconazole vaginal cream and suppositories are for use only in the vagina. These products are not to be taken by mouth. The vaginal suppositories are inserted, one per dose, in an applicator. Alternatively, the tube containing the vaginal cream is screwed onto the end of a special applicator tube, and the tube is then squeezed to fill the applicator. The patient then lies on her back with bent knees, inserts the applicator containing either the suppository or cream so that the tip of the applicator is high in the vagina, and then pushes the plunger in to deposit the suppository or cream into the vagina. The applicator should be washed with warm soap and water after each use.

Miconazole usually is used once daily at bedtime. The 200 mg suppositories (Monistat 3) are inserted once nightly for 3 nights. The 100 mg suppositories (Monistat-7) and intravaginal cream are inserted once nightly for 7 nights. The 1200 mg formulation (Monistat 1) is applied once for one night.

Metronidazole

• Alcohol should be avoided because metronidazole and alcohol together can cause severe nausea, vomiting, cramps, flushing, and headache.
• Metronidazole can increase the blood thinning effects of warfarin (Coumadin, Jantoven) and increase the risk of bleeding probably by reducing the breakdown of warfarin.
• Cimetidine (Tagamet) increases blood levels of metronidazole while cholestyramine (Questran, Questran Light) reduces blood levels of metronidazole by reducing its absorption.
• Metronidazole should not be combined with amprenavir (Agenerase) for treating human immunodeficiency disease (infection with HIV) because amprenavir contains propylene glycol.
• Metronidazole blocks the breakdown of propylene glycol in the liver leading to accumulation of propylene glycol in blood. Accumulation of propylene glycol could cause seizures, increased heart rate, and lead to kidney failure.
• Metronidazole increases the blood levels of carbamazepine (Tegretol, Tegretol XR, Equetro, Carbatrol), lithium (Eskalith, Lithobid) and cyclosporine though unknown mechanisms. Serious reactions may occur if these drugs are taken with metronidazole.

Miconazole

There are no known drug interactions with vaginal or topical miconazole.

Metronidazole

• Metronidazole is not used in early pregnancy because of potential adverse effects on the fetus.
• Metronidazole is excreted in breast milk. Females who are nursing, because of potential adverse effects on the newborn, should not use metronidazole.

Miconazole

• There is very limited information on the use of miconazole during pregnancy. The physician must weigh the potential benefits against possible but unknown risks to the fetus.
• It is not known if miconazole is secreted in breast milk in amounts that can affect the infant.