Can I treat a yeast infection while taking metronidazole?

October 9, 2025 •

3 min read

Approximately 10% of women who take metronidazole experience a subsequent vaginal yeast infection. This often occurs because metronidazole, an antibiotic for bacterial infections like BV, can disrupt the vaginal flora, leading to an overgrowth of Candida fungus. This guide explores whether you can treat a yeast infection while taking metronidazole and the right steps to take.

Quick Summary

Yes, you can treat a yeast infection while on metronidazole, but you must use a separate antifungal medication because metronidazole only targets bacteria. Discuss co-treatment with a healthcare provider for a proper diagnosis and treatment plan for both infections.

Key Points

Metronidazole Does Not Treat Yeast Infections: This antibiotic is for bacteria and parasites, and is ineffective against the fungus that causes yeast infections.
Metronidazole Can Cause a Yeast Infection: By disrupting the natural vaginal flora, the antibiotic can lead to an overgrowth of Candida fungus.
Co-Infections Are Common: It is possible to have both bacterial vaginosis and a yeast infection at the same time, which requires dual treatment.
Treatment Requires Both Medications: For co-infections, a healthcare provider will prescribe metronidazole for the bacterial infection and a separate antifungal medication for the yeast.
Antifungals and Metronidazole Are Generally Safe Together: Under a doctor's supervision, the two can be taken concurrently, although caution is advised for individuals with certain heart conditions.
Symptoms Can Be Confusing: BV and yeast infections have overlapping symptoms, making an accurate medical diagnosis essential for proper treatment.

Understanding the Purpose of Each Medication

Metronidazole (often sold under brand names like Flagyl) is an antibiotic designed to kill certain types of bacteria and parasites, not fungi. It is most commonly prescribed to treat bacterial vaginosis (BV) and trichomoniasis. Yeast infections, on the other hand, are caused by an overgrowth of the fungus Candida and must be treated with a specific antifungal medication.

Why Metronidazole Doesn't Treat a Yeast Infection

Misunderstanding the role of metronidazole is a common issue. Taking metronidazole for a yeast infection is ineffective and can potentially worsen the situation. The medication works by damaging the DNA of susceptible bacteria, a mechanism of action that does not harm the fungal cells responsible for yeast infections. In fact, by eliminating the “good” bacteria that help control yeast growth, the antibiotic can actually trigger a yeast infection.

Treating Co-existing Infections

It is possible to have a vaginal co-infection, where you have both bacterial vaginosis and a yeast infection simultaneously. In this case, a healthcare provider will likely prescribe both metronidazole and an antifungal treatment. For example, a doctor might prescribe oral metronidazole for BV and an oral antifungal pill like fluconazole or a topical antifungal cream for the yeast infection. These two types of medications can generally be taken at the same time, but only under a doctor's guidance.

Diagnosing a Co-infection

Because the symptoms can be similar, it is crucial to get a proper diagnosis from a healthcare provider. A pelvic exam and a sample of vaginal discharge can help confirm whether you have BV, a yeast infection, or both. Self-diagnosing can lead to incorrect or ineffective treatment. For example, relying on an over-the-counter yeast infection treatment for what is actually BV will not resolve the underlying bacterial issue.

Comparing Bacterial Vaginosis and Yeast Infection Symptoms


Symptom	Bacterial Vaginosis (BV)	Yeast Infection
Discharge Appearance	Thin, watery, and grayish-white	Thick, white, and clumpy (like cottage cheese)
Odor	Distinctive, strong “fishy” odor, especially after sex	No significant or distinct odor
Itching	Mild or sometimes absent	Intense vaginal and vulval itching
Pain/Irritation	General vaginal discomfort; irritation from excess discharge	Burning sensation during urination or sex; vulval redness and swelling

Important Considerations When Combining Medications

If a healthcare provider determines that co-treatment is necessary, it is essential to follow their instructions carefully. Here are some key points to discuss:

Potential Drug Interactions: While generally safe together, combining medications can have risks. The combination of fluconazole and metronidazole has been shown to potentially increase the risk of an irregular heart rhythm (torsade de pointes) in rare cases, especially in individuals with pre-existing heart conditions or electrolyte imbalances.
Monitoring: Your doctor may suggest closer monitoring during treatment, particularly if you have risk factors for heart rhythm problems.
Side Effects: Discuss any side effects you experience. Common side effects of metronidazole include nausea, a metallic taste in the mouth, and headache. Antifungals can also cause various side effects.
Risk of Recurrence: Some treatments, like metronidazole, can disrupt the vaginal microbiome. To reduce the risk of a recurrent BV or yeast infection, your doctor might recommend probiotics.
Completing the Full Course: Always finish the entire course of medication as prescribed. Stopping prematurely, even if symptoms improve, can increase the risk of the infection becoming resistant to treatment.

What to Do If You Develop a Yeast Infection After Taking Metronidazole

If you finish your metronidazole treatment and then develop yeast infection symptoms (itching, thick white discharge), it's important to contact your doctor again. Do not start using leftover metronidazole or self-diagnose based on past infections. Your doctor can prescribe the correct antifungal medication, such as an oral dose of fluconazole or a topical antifungal cream.

Conclusion

While you cannot treat a yeast infection with metronidazole, you can and should treat a yeast infection while taking metronidazole if you have both infections. The crucial first step is to see a healthcare provider for an accurate diagnosis, as metronidazole treats bacteria while antifungals treat yeast. Co-treatment with an antibiotic and an antifungal is a common and often necessary approach for concurrent infections. Always follow your doctor's guidance to ensure both infections are properly cleared and to minimize side effects.

Visit ACOG for more information on vaginal health.

Frequently Asked Questions

Yes, you can use an over-the-counter antifungal cream or suppository (like Monistat, which contains miconazole) to treat a yeast infection while on a course of metronidazole. However, you should confirm with your healthcare provider first, especially to ensure your symptoms are actually from a yeast infection and not an unrelated issue or a worsening of your original condition.

No, you do not need to wait. If you have a co-infection, a doctor may have you start both treatments simultaneously. If the yeast infection appears later as a side effect, you can begin antifungal treatment while still on metronidazole. A healthcare professional can advise on the best timing.

Symptoms of a yeast infection caused by metronidazole are the same as any other yeast infection. They include intense vaginal itching and burning, a thick, white, cottage cheese-like discharge, and redness or irritation of the vulva.

Yes, it is generally safe to take oral fluconazole (Diflucan) and oral metronidazole (Flagyl) together if prescribed by your doctor. However, individuals with a history of certain heart rhythm problems (like long QT syndrome) may require special monitoring due to a rare risk of complications.

A yeast infection typically presents with a thick, white, odorless discharge and intense itching. BV is more often characterized by a thin, watery, grayish-white discharge with a distinct fishy odor, though it may cause less itching. A proper diagnosis from a doctor is the only definitive way to know.

While it is not always preventable, some women at high risk for developing yeast infections after antibiotics are sometimes prescribed an antifungal medication proactively by their doctor. Discuss this with your healthcare provider if you have a history of developing yeast infections after antibiotic use.

If your symptoms worsen or change significantly, you should contact your healthcare provider. This could indicate a co-infection, a medication side effect, or another condition that needs to be addressed with a different treatment plan.