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Key takeaways
Metronidazole is an antibiotic used to treat bacterial infections caused by anaerobic bacteria, such as bacterial vaginosis (BV).
It is not an appropriate treatment for a yeast infection, which requires antifungal medication.
BV and vaginal yeast infections can cause similar symptoms. Seek medical advice from a healthcare professional to get the right treatment.
Metronidazole is an antibiotic often prescribed for certain bacterial infections, including those of the skin, joints, bones, nervous system, gastrointestinal tract, and reproductive system. While it’s often used to treat bacterial vaginosis (BV), it’s not an appropriate treatment for vaginal yeast infections, which have similar symptoms. Here’s why you shouldn’t expect your healthcare provider to prescribe metronidazole.
Can metronidazole actually treat a yeast infection?
The short answer is that metronidazole doesn’t treat yeast infections.
Metronidazole is a nitroimidazole antibiotic that stops the growth of infections caused by anaerobic bacteria–that is, bacteria that don’t need oxygen to survive. It can also be used to treat certain protozoan infections, such as giardiasis. Yeast infections are caused by the overgrowth of Candida, a fungus that normally lives in the body. They require treatment with an oral antifungal medication, such as Diflucan (fluconazole) or a vaginal antifungal cream, such as Monistat (miconazole) or terconazole.
Metronidazole is available in three forms, often used to treat different conditions:
- Oral metronidazole (brand name Flagyl): Treats multiple types of infections such as trichomoniasis (sexually transmitted infection), abdominal infections, and gynecologic infections, among others.
- Topical gel (brand names MetroGel, Vandazole): Treats skin conditions, such as rosacea
- Vaginal metronidazole gel (brand name Nuvessa): Treats localized infections, such as bacterial vaginosis
Bacterial vaginosis (BV) and yeast infections may have similar symptoms, such as vaginal itching or irritation, discharge, and odor, as well as a burning sensation during sexual intercourse or while urinating. So it’s easy to get them confused. Metronidazole is a common treatment for BV, but not for yeast infections.
“A healthcare provider can help determine the cause of the infection and recommend appropriate treatment options to resolve the issue,” says Sweta Patel, DO, physician manager for OB-GYN Associates of Advantia. “Self-treating incorrectly can delay proper care, worsen symptoms, and increase risk of recurrence or complications.”
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Can metronidazole cause yeast infections?
In a healthy vagina, there’s a balance of many different kinds of bacteria. Adding an antibiotic to the mix can disrupt the bacterial balance, allowing yeast to proliferate. Most antibiotics can cause yeast infections, with some types of antibiotics carrying a higher risk.
“All medications have side effects. Metrodinazole is no different,” says Lipi Roy, MD, internist and founder of SITA MED. “One of its side effects is increased risk of yeast infections, namely candidiasis. It disrupts normal bacterial flora, which can allow the overgrowth of Candida species.” Other common side effects include loss of appetite, constipation, a metallic taste in your mouth, stomach cramps, and other gastrointestinal (GI) side effects.
However, that doesn’t mean you should avoid taking metronidazole if your healthcare provider prescribes it. In most cases, the benefits of treating your infection outweigh the small risk of a yeast infection.
Is it a yeast infection or BV?
While many of the symptoms of bacterial vaginosis and a yeast infection are very similar, there is one type of symptom that may help you distinguish between the two: vaginal discharge. A yeast infection can cause a thicker discharge, often compared to cottage cheese, that is typically odorless. BV may cause a thinner, grayish-white discharge with a fishy odor.
Neither BV nor vaginal candidiasis is classified as a sexually transmitted infection (STI), but you can spread both of these infections to a sexual partner. BV is more likely to occur in people who are sexually active, especially in people with multiple sex partners or who have a new sex partner, because sexual activity can alter vaginal pH.
Research suggests that recurrent BV may be a trigger for recurrent vaginal yeast infections, even though BV and yeast infections are caused by different things.
Yeast infection vs. BV |
||
|---|---|---|
| Condition | Yeast infection | Bacterial vaginosis |
| Type of infection | Fungal | Bacterial |
| Symptoms |
|
|
| Cause | An overgrowth of the fungus Candida | An overgrowth of harmful anaerobic bacteria that disrupts the natural balance of beneficial bacteria (lactobacilli) in the vagina |
| Treatment | Antifungal medication, such as fluconazole, miconazole, or terconazole | Antibiotic medication, such as metronidazole |
Preventing yeast infections when taking metronidazole
It might seem like a good idea to take an antifungal medication in anticipation of a possible yeast infection if you’re taking metronidazole. Not so fast, says Dr. Roy. “There’s limited evidence to support prophylactic antifungal use, and therefore, it’s not recommended.”
However, there are a few other strategies that might help you ward off a yeast infection while taking an antibiotic, such as:
- Taking probiotics that contain Lactobacillus
- Wearing breathable cotton underwear
- Avoiding tight leggings and opting for looser clothing
- Changing quickly out of wet clothing and bathing suits
- Using unscented, gentle cleansers
- Avoiding douching
In addition, there are some other things to avoid while taking metronidazole beyond yeast infection prevention. Experts caution people to avoid drinking alcohol or eating foods containing propylene glycol during their course of antibiotics and for three days after finishing the medication. Propylene glycol is found in many processed foods such as baked goods, candy, and soft drinks. Watch out for over-the-counter cough and cold syrups, too, as some contain propylene glycol.
Let your healthcare provider know if you’re taking any of these prescription medications, since there is also a risk of drug interaction with metronidazole:
- Warfarin
- Lithium
- Disulfiram
- Phenytoin or phenobarbital
- Busulfan
- Mycophenolate
- Cimetidine
In fact, you should always give your healthcare provider a complete list of all prescription drugs, over-the-counter medications, vitamins, or supplements before you start a new treatment.
What if you already have a yeast infection after metronidazole?
“If a patient develops a yeast infection after taking metronidazole, it is important that they continue to take the antibiotic to get rid of the infection the medication is treating,” Dr. Patel says. “Untreated BV can result in more serious health risks, including an increased risk of contracting STIs and pregnancy complications.”
Then, consult your healthcare provider for diagnosis and treatment of the yeast infection. Chances are, your provider will probably recommend oral fluconazole or miconazole cream. “But the doctor should perform an appropriate history and tailor the treatment plan to the individual patient,” Dr. Roy adds.
The bottom line
If you have vaginal itching or discharge, it may be tempting to pop into a drug store to pick up an over-the-counter treatment for a yeast infection. However, the best course of action is to see your healthcare provider to make sure you have the correct diagnosis. If you have BV, metronidazole may be a good option, but you need to know for sure so your provider can recommend the best treatment.
- Bacterial vaginosis and vulvovaginal candidiasis pathophysiologic interrelationship, Microorganisms (2024)
- Metronidazole vaginal gel, Mayo Clinic
- Metronidazole (oral route), Mayo Clinic
- Taking or using metronidazole with other medicines and herbal supplements, NHS (2025)
- Use of probiotic lactobacilli in the treatment of vaginal infections: In vitro and in vivo investigations, Frontiers in Cellular and Infection Microbiology (2023)
- Vaginal yeast infection, Cleveland Clinic (2025)
- What is propylene glycol, and what does it do in our food?, International Food Information Council (2021)
- Yeast infection (vaginal), Mayo Clinic