Brand Name:Apo-Metronidazole, Flagyl, Florazole ER, MetroCream, MetroGel, MetroLotion, Metronidazole Injection, NidaGel, Noritate

Prescription needed: Yes

What is this drug used for?

Metronidazole is used in the treatment of many types of bacterial infections such as those associated with colitis, gum disease, pressure sores and leg ulcers. It is prescribed in infections such as trichomonas vaginitis (trich), which is acquired through sexual intercourse with an infected person. Metronidazole is also prescribed in cases of dysentery and for giardiasis, a waterborne illness which causes severe diarrhea. In combination with other drugs, it is used for the treatment of peptic ulcers caused by H. pylori infection.

Metronidazole is available in different dosage forms such as oral tablets, intravenous (injection to the veins) form and vaginal preparations.

In topical form, it is used to treat rosacea (a facial skin disorder that resembles acne).

Is there any reason not to take this drug?

You should not use this product if you are allergic to metronidazole. Tell your doctor if you are allergic to parabens (a kind of preservative), which is present in the Metrogel formulation. Tell your doctor if you have or have ever had:

  • blood disorders
  • central nervous system disorders (including epilepsy or seizures)
  • liver disease
  • under-active thyroid (hypothyroidism)
  • a problem with alcohol use

What about possible side effects?

Side effects to this medication will depend on the type of dosage form you are taking. For example, side effects will be more common with the tablets and injection to the veins and less so with the topical or vaginal forms.

Some common side effects are:

  • loss of appetite
  • nausea
  • metallic taste in mouth
  • dark urine (temporary)

You many take oral metronidazole tablets with food to minimize stomach upset.

These side effects are usually related to dose and should go away with time.

Topical dosage form:

  • stinging or burning skin
  • dry skin
  • eye irritation (do not apply too close to eye area)

Vaginal dosage form:

  • vaginal itching or irritation
  • vaginal discharge
  • menstrual discomfort

Other less common side effects include:

  • dry mouth
  • dizziness
  • headache (more common with Florazole ER, extended release tablet)

Other less common and potentially serious side effects include:

  • numbness or tingling in the extremities
  • confusion
  • chest pain or palpitations (rare)
  • seizures
  • a condition called leukopenia - call your doctor immediately if you experience unexplained sore throat, fever, chills, or other signs of infection
  • a condition called thrombocytopenia - call your doctor immediately if you experience any increase in bruising or bleeding.

Vaginal dosage form:

  • Burning on urination
  • Need to urinate more often

This is not a complete list of side effects. If you are concerned about these or other unusual symptoms while taking this medication, ask your doctor and/or pharmacist for more information and advice.

What if I am taking other drugs?

Always provide your doctor with a list of all other drugs you are taking (including over-the-counter medications and herbal/natural products) as they may interact and may change the safety or effectiveness of either drug. This includes other topical preparations applied to the same area of skin as topical metronidazole preparations. Tell your doctor specifically if you are taking any of these drugs as these are the most common interactions and he/she may need to make changes or monitor you more closely:

  • anti-coagulants (such as warfarin) - may have increased chance of bleeding
  • transplant medications such as cyclosporine, tacrolimus - increased blood levels, which will increase chances of side effects
  • disulfiram - could cause confusion or central nervous system side effects when combined with metronidazole
  • lithium - may have an increased chance of experiencing lithium toxicity
  • phenytoin - may increase chance of side effects with phenytoin and lower the effect of metronidazole

This is not a complete list of drug interactions. Ask your doctor or pharmacist to review your list of medications.

Other information:

Metronidazole will affect the results of certain tests. If you are planning to have any medical tests, talk to your doctor.

If you are taking this medicine for trichomoniasis, your doctor may want to treat your sexual partner at the same time as you are being treated, even if he or she has no symptoms. This will help keep you from getting the infection back again from your partner.

How to take: Always follow the specific instructions for the specific dosage form. Talk to your doctor or pharmacist.

If you experience stomach upset with regular oral metronidazole tablets, you may take it with food.

If you are taking Florazole ER (extended release tablet), do not crush. Take the extended release tablet 1 hour before or 2 hours after a meal.

Children: Lower dose may be necessary.

Seniors: Lower doses may be necessary.

Pregnant women: Not recommended in the first trimester. Risk versus benefits should be discussed with your doctor.

Women who are nursing: Passes into breast milk. Not generally recommended. If you are treated with metronidazole for a specific situation, the breast milk should be expressed and discarded during treatment. Breast-feeding may be resumed 24 to 48 hours after treatment. Talk to your doctor.

People who drive or operate machinery: Should not do so until they know how this drug affects them personally; may cause dizziness.

Alcohol: Do not drink alcohol during treatment and for at least 1 day after treatment with metronidazole as it is likely to cause a variety of adverse effects including headache, flushing of the face, and nausea and/or vomiting. This includes any beverages containing alcohol and medications that contain alcohol, such as cough syrups and/or cold medicine (e.g. Nyquil). If you are taking extended release tablets (Florazole ER) you should not drink alcohol for at least 3 days after treatment.

Overdose: If you experience any unusual symptoms call your doctor or 911.

Stopping the drug: You must finish the full course of treatment to completely clear up your infection. If you stop taking this medicine too soon, the infection may still be present and symptoms may return.

If you miss a dose: Take as soon as you remember. If it is just about time to take your regular dose, take it now and skip the next dose. Never take a double dose.

Storage conditions: Closed container; cool, dry location away from excess moisture (not in the bathroom) and light; always out of reach of children.

Dietary precautions: None