Flagyl is well-known for causing diarrhea, as well as other stomach side effects like nausea, heartburn and stomach pain. Diarrhea is common and occurs in about 1% to 10% of patients. Flagyl may also cause an unpleasant metallic taste during therapy which can lead to nausea and a decreased appetite.

Stomach side effects are enough to make some people abandon Flagyl therapy altogether, but don't -- call your doctor before you stop any antibiotic treatment.

To help recover from a bout of mild diarrhea, be sure to stay hydrated, replace electrolytes, and eat a bland diet like bananas, rice, applesauce, and toast (BRAT diet). Most cases of antibiotic-associated diarrhea, while unpleasant, are usually a short-lived side effect and should clear up a few days after the antibiotic is stopped. If not, be sure to contact your prescriber.

The regular-release metronidazole tablets can be taken with a meal, a snack or a glass of milk to help prevent an upset stomach. If heartburn is an issue, ask your doctor if you can take an over-the-counter acid blocker like famotidine (Pepcid AC).

If you simply cannot tolerate the side effects, speak with your doctor about what other options you might have. Also, don't ever share this medication with anyone - it's very specific for the type of infection it treats and may be harmful if taken by someone else without a doctor's okay. It has no action on viral infections like a cough, cold, the flu, or COVID.

What is Flagyl?

Flagyl (generic name: metronidazole) is a bactericidal (kills bacteria) antibiotic and is also used to treat protozoal infections like Trichomoniasis, Giardiasis or Amebiasis. It's used to treat ominous sounding organisms such as Bacteriodes fragilis, Helicobacter pylori, and Giardia lamblia.

Flagyl is used to treat many common infections like:

• bacterial vaginosis
• bacterial stomach or intestinal infections
• pelvic inflammatory diseases
• trichomoniasis (sexually transmitted infection due to a parasite)

In addition to tablets, it's also available in an intravenous (IV) formulation for injection, and as a cream or lotion for use in acne treatment or rosacea, and in a topical gel for vaginal infections (bacterial vaginosis).

Be sure to take the full course of antibiotic treatment that your doctor prescribes. The side effects may be somewhat difficult, but a recurring infection can be serious if you stop therapy.

Can Flagyl cause severe diarrhea?

It's bad enough you have an infection. But now your treatment has caused antibiotic-associated diarrhea. This happens because the population of "good" bacteria (normal microflora) in your intestine are altered due to your antibiotic. Symptoms can range from soft stools to frequent and explosive watery diarrhea.

Clostridium difficile

A more severe case of infectious diarrhea called Clostridium difficile ("C. diff" for short) can happen with almost any antibiotic, and is more common when hospitalized. C. diff is a bacteria that lives in our intestines.

Common symptoms of C. diff include:

• watery diarrhea
• blood or pus in bowel movements
• fever
• stomach pain or cramps
• nausea
• loss of appetite
• dehydration (you may have dark urine or feel thirsty, tired, dizzy or confused)

Here's an important point to remember: if you have severe diarrhea that is watery, bloody, or contains mucus; several loose bowels in one day; stomach cramping or fever; or nausea, call your doctor right away. Also, avoid any over-the-counter antidiarrheal medicine unless your doctor recommends it.

C. diff is contagious and can spread to other people or surfaces. People who are not taking antibiotics can get infected if they touch an infected person or surface and then don't wash their hands. Serious complications can include inflammation of the intestine known as pseudomembranous colitis.

Metronidazole (Flagyl) is sometimes used to treat C. difficile, but your doctor may elect to use a different treatment, so it’s important to contact them right away.

How can I prevent diarrhea with Flagyl?

To help prevent antibiotic-associated diarrhea, you might:

• take Flagyl only when necessary to treat bacterial infections as prescribed by your doctor. They won’t help viral infections like a cold or flu.
• let your doctor know if you’ve previously had antibiotic-associated diarrhea.
• keep your hands well washed after using the restroom. If you have a caregiver in your home or at the hospital, ask them to wash their hands with soap and water before touching you.
• talk to your doctor about the use of probiotics. Probiotics are certain "good" bacteria found in the intestines. They can also be found in supplements and certain foods, like yogurt. Some studies suggest they may be helpful to treat or prevent antibiotic-associated diarrhea. But there's no final consensus on if they are helpful to prevent or lessen the symptoms of antibiotic-associated diarrhea.

This is not all the information you need to know about Flagyl (metronidazole) for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.