Metronidazole (Flagyl): Uses, Side Effects, Interactions & More - GoodRx (2024)

Pharmacist tips for Metronidazole (Flagyl)

More tips for the metronidazole (Flagyl) extended-release (ER) tablets

What are the risks and warnings for Metronidazole (Flagyl)?

It’s not clear whether or not taking metronidazole (Flagyl) can put you at risk for cancer. Studies show that rats who took this medication throughout their lifetime were at higher risk for tumors in the liver, lung, and different organs. If you're taking metronidazole (Flagyl), don't take this medication more often than what your primary care provider has directed.

Metronidazole (Flagyl) can sometimes cause rash and other severe skin reactions, such as Stevens-Johnson syndrome (SJS). If you experience these reactions, your care team will need to stop metronidazole (Flagyl) right away and switch you to a different medication. If you've a rash, blisters on your lips, skin peeling, skin pain, mouth sores, or high fever, get medical help immediately.

Rarely, people who take metronidazole (Flagyl) can develop serious brain and nerve problems, such as seizures, encephalopathy (a health condition that leads to brain damage) or meningitis (inflammation of the brain lining). Get medical attention right away if you experience convulsions, problems with speech, coordination, clear thinking, headache, nausea, vomiting, stiff neck, and sensitivity to light. These are symptoms of brain damage and your care team might ask you to stop taking metronidazole (Flagyl) to prevent further injury. Symptoms can develop within hours of treatment, but will also go away within days to weeks of stopping this medication.

In addition, people who take metronidazole (Flagyl) might also experience different nerve problems. Let your primary care provider know if you experience numbness in the hands and feet, pain when moving the eye, or changes in vision. Your primary care provider will discuss with you whether metronidazole (Flagyl) is a good option for you.

People with liver or kidney problems who take metronidazole (Flagyl) might have a higher amount of the medication in the blood. This can lead to higher risk of side effects, such as nausea, headache, and seizures. Depending on how severe your liver or kidney problems are, your care team will help you determine the lowest possible dose of metronidazole (Flagyl) that is safe for you. If you experience symptoms of liver problems (feeling sleepy, upper right stomach pain, yellowing of the skin or eyes, dark urine) or kidney problems (urinating more or less than usual, feel nauseous or weak, have a fever, rash, joint pain), talk with your care team right away.

Taking metronidazole (Flagyl) can raise your risk of getting a fungal infection, including a vaginal yeast infection. It's important to let your care team know if your symptoms don't go away or get worse after starting treatment. Your primary care provider might prescribe an antifungal medication for you if symptoms develop. Please talk with your care team if you notice your vagina is red and itchy, you have thick white vaginal fluid, or if you've fever or chills.

Taking metronidazole (Flagyl) more often or differently than prescribed can put you at risk for infections that are harder to treat in the future. To make sure that this medication will work well to fight future infections, follow your care team's instruction on when and how long to take metronidazole (Flagyl).

Though extremely rare, some people developed lower white blood cell count while taking metronidazole (Flagyl). This can put you at higher risk for infections. Your primary care provider will typically require lab work before and while you're taking this medication to make sure it's safe for you. Let your care team know if you've symptoms of low white blood cells, such as fever, chills, weakness, fast heart beat, sores in the mouth and throat.

Metronidazole (Flagyl) can interfere with how your body gets rid of other medications. For example, taking certain medications like disulfiram with metronidazole (Flagyl) can cause delusions and hallucinations. These medications should be avoided together.

When metronidazole (Flagyl) is taken with lithium, it can raise the amount of lithium in your body. This can lead to higher risk of lithium toxicity and side effects, such as confusion, tremors, and uncontrolled eye movements.

Metronidazole (Flagyl) can also raise the risk of bleeding when it's taken with certain blood thinners, such as warfarin (Coumadin). Make sure to get your routine blood tests done on time during treatment.

Let your care team know what other medications you’re taking before and while taking metronidazole (Flagyl).

Metronidazole (Flagyl) dosage forms

The typical dosing for metronidazole (Flagyl) can differ for each person depending on what type of infection you have. Your dose might also differ if you have kidney or liver problems.

Adults

Immediate-release tablets

• Trichomoniasis (1-day course): The typical dosing is 2 grams by mouth, taken as a single dose or split into 2 doses and taken in one day.

• Trichomoniasis (7-day course): The typical dosing is 250 mg by mouth 3 times daily for a week.

• Amebiasis: The typical dosing ranges from 500 mg to 750 mg by mouth 3 times daily for 5-10 days.

• Bacterial infections: Dosing for certain bacterial infections will depend on your weight and the severity of the infection. The typical dosing is 7.5 mg/kg of body weight by mouth every 6 hours for 7-10 days. The maximum recommended dose is 4 grams daily.

Immediate-release capsules

• Trichomoniasis: The typical dosing is 375 mg by mouth 2 times daily for a week.

• Amebiasis: The typical dosing is 750 mg by mouth 3 times daily for 5-10 days.

• Bacterial infections: Dosing for certain bacterial infections will depend on your weight and the severity of the infection. The typical dosing is 7.5 mg/kg of body weight by mouth every 6 hours for 7-10 days. The maximum recommended dose is 4 grams daily.

Extended-release tablets

• Bacterial vaginosis: The typical dosing is 750 mg by mouth once a day for a week.

Children

IR tablets and capsules

• Amebiasis: Your child's pediatrician will determine the dose based on your child's body weight. The typical dose is 35-50 mg/kg of body weight by mouth daily, split into 3 doses and taken throughout the day for 10 days.