What is Metronidazole: Uses, Warnings & Interactions

Metronidazole is taken orally, applied topically, or given as an intravenous infusion.

Take the medicine as directed.

Take the full course of medicine even if symptoms improve early. The entire multi-day regimen is required to fully eradicate the infection.

Metronidazole is typically taken in one to four doses a day. Space the doses as evenly as possible across the day or as directed by your doctor.

How to take metronidazole tablets or capsules

• The tablets or capsules can be taken with or without food as directed by your doctor. 

• If you experience an upset stomach after taking the medication, try taking the next doses with a meal or snack.

• Swallow the tablet or capsule whole with a full glass of water. Do not crush, break, or chew it.

• Store metronidazole tablets and capsules in a dry place at room temperature.

How to take metronidazole extended-release tablets

• Take extended-release tablets on an empty stomach one hour before or two hours after a meal.

• Swallow the tablet whole with a full glass of water. Do not chew, crush, or split it.

• Store metronidazole extended-release tablets in a dry place at room temperature.

How to take metronidazole oral suspension

• Metronidazole oral suspension can be taken with or without food. 

• If you experience an upset stomach after taking the medication, try taking the medicine with food.

• Shake the bottle well before measuring out a dose.

• Use the calibrated oral syringe that came with the medicine to measure out a dose. Do not use kitchen or table utensils.

• Store metronidazole oral suspension in a closed container at room temperature.

• Throw out any remaining medicine 10 days after opening the bottle.

How to take metronidazole cream, lotion, or gel

• Wash the affected skin area with a mild cleanser.

• Apply and gently rub in a thin layer of the metronidazole lotion, gel, or cream to the affected area. 

• Store topical metronidazole at room temperature. Do not freeze.

How to take metronidazole vaginal gel

• Consult a healthcare provider for instructions on the appropriate application before use.

• Metronidazole vaginal gel can be administered using an applicator that is either prefilled or manually filled from a tube before use.

• When filling an empty applicator (Vandazole or Perrigo metronidazole gel), attach and screw in the open end of the applicator to the tube. Squeeze in the medicine until the applicator is full.

• If using a prefilled applicator like Nuvessa, remove the orange cap before insertion.

• In a relaxed position, preferably on your back, gently insert the applicator.

• Slowly and fully press the plunger.

• Remove the applicator and dispose of it properly. Do not use applicators for more than one dose.

• Do not have vaginal intercourse or use vaginal products while you are being treated with metronidazole vaginal gel.

• Store at room temperature protected from extreme heat or cold. Do not freeze.

DO NOT MISS DOSES. If you keep forgetting doses, talk to a healthcare provider or pharmacist about tools that can help you remember.

Take a missed dose as soon as it’s remembered. However, if it is almost time for the next dose, skip the missed dose and take the next scheduled dose on time. 

Do not take extra medicine to make up for a missed dose.

If you’re using topical or vaginal metronidazole, ask the prescribing healthcare for advice on taking missed doses.

This medicine is not right for everyone. 

Do not use metronidazole in any dosage form if you have had an allergic reaction to metronidazole or similar medicines (any drug that ends in –idazole). 

Oral or intravenous metronidazole cannot be given to people with Cockayne syndrome.

Tell any doctor or other healthcare provider who treats you that you are using this medicine.

Your doctor may need to examine you or perform blood tests to monitor the effects of this medicine. Keep all appointments.

Call your doctor if your symptoms do not improve or if they get worse.

Tell your doctor if you are pregnant or breastfeeding.

Tell your doctor if you have:

• Kidney disease

• Liver disease

• A yeast infection (including oral thrush)

• A history of seizures

• A history of blood or bone marrow problems

This medicine may cause potentially serious brain or nervous system problems. Some of these problems can develop within hours of taking the first dose. Most resolve after the drug is stopped, so immediately talk to a healthcare provider if you have neurological symptoms such as those listed in the side effects section below.

This medicine can also cause problems such as:

• Worsening of yeast infections

• Blood problems including a decrease in infection-fighting white blood cells

• Abnormal heart rhythms

• Liver problems

If metronidazole is used to treat an STD:

• Take measures to prevent spreading the infection

• Use a condom for sexual intercourse

• The doctor may want to also treat your sexual partner, even if he or she has no symptoms

Stop using metronidazole vaginal gel and contact the prescribing healthcare provider if you experience vaginal irritation.

To avoid potentially hazardous drug interactions, tell the prescribing healthcare provider about all prescription drugs, over-the-counter medications, and supplements you use before taking metronidazole.

Tell other healthcare providers you are using this medicine before they prescribe new medications.

DO NOT DRINK ALCOHOL or consume anything with propylene glycol when taking oral metronidazole and for three days after you’ve stopped. The combination can make you feel very sick.

DO NOT USE METRONIDAZOLE if you are taking disulfiram, a drug used to help people stop drinking. The combination can bring on a psychotic reaction. Disulfiram has to be stopped at least two weeks before metronidazole can be safely taken.

Before taking metronidazole, make sure to tell your doctor if you are also taking:

• Any type of blood thinner

• The seizure medications phenobarbital or phenytoin

• The stomach acid reducer cimetidine

• The bipolar medication lithium

• The cancer drug busulfan

Find out more about metronidazole interactions to avoid here.