Metronidazole for Women: Side Effects, BV Relief, and Your Next Steps

If you've been prescribed metronidazole, you're likely dealing with a bacterial infection—most commonly bacterial vaginosis (BV). Metronidazole is one of the most widely recommended and evidence-based treatments for BV and several other infections in women.

Understanding how it works, what side effects to expect, and when to follow up can help you feel more confident about your treatment and recovery.

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What Is Metronidazole?

Metronidazole is an antibiotic that targets anaerobic bacteria (bacteria that thrive without oxygen) and certain parasites. It works by damaging the DNA of these organisms, stopping them from multiplying.

In women, it is commonly prescribed for:

• Bacterial vaginosis (BV)
• Trichomoniasis (a sexually transmitted infection)
• Certain pelvic or abdominal infections
• Some dental or gastrointestinal infections

For BV, metronidazole is considered a first-line treatment by major medical organizations.

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How Metronidazole Treats Bacterial Vaginosis (BV)

Bacterial vaginosis happens when the normal balance of bacteria in the vagina shifts. Healthy vaginal bacteria (mainly Lactobacillus) decrease, and other bacteria overgrow.

Common BV symptoms include:

• Thin gray or white discharge
• A strong, "fishy" odor (often worse after sex)
• Mild irritation or burning
• Sometimes no symptoms at all

Metronidazole helps by reducing the overgrowth of harmful bacteria, allowing the healthy bacteria to restore balance.

Common Treatment Options for BV

Metronidazole may be prescribed as:

• Oral tablets (usually 500 mg twice daily for 7 days)
• Vaginal gel (0.75%) used once daily for 5 days

Both forms are effective. Your doctor may recommend one over the other based on:

• Personal preference
• Side effect concerns
• Recurring BV
• Other health conditions

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How Quickly Does Metronidazole Work?

Many women notice improvement in symptoms within 2–3 days, but it's critical to:

• Finish the entire prescription
• Even if symptoms improve early
• Even if discharge or odor goes away

Stopping early increases the risk that BV will return.

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Common Side Effects of Metronidazole in Women

Like all medications, metronidazole can cause side effects. Most are mild and temporary.

Common Side Effects

• Nausea
• Metallic taste in the mouth
• Loss of appetite
• Mild stomach upset
• Headache
• Dry mouth

If using vaginal gel:

• Mild vaginal irritation
• Yeast infection (occasionally)

These symptoms typically resolve after finishing treatment.

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Important: Alcohol and Metronidazole

One of the most well-known precautions with metronidazole is to avoid alcohol.

Drinking alcohol while taking metronidazole can cause:

• Severe nausea
• Vomiting
• Flushing
• Rapid heartbeat
• Headache

To stay safe:

• Avoid alcohol during treatment
• Avoid alcohol for at least 24–48 hours after finishing

Even small amounts can cause unpleasant reactions.

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Serious but Rare Side Effects

Serious reactions are uncommon, but it's important to recognize them.

Seek medical care immediately if you experience:

• Severe allergic reaction (rash, swelling, trouble breathing)
• Numbness or tingling in hands or feet
• Seizures
• Severe abdominal pain
• Persistent vomiting
• Signs of liver problems (yellowing of skin or eyes)

If something feels severe or unusual, speak to a doctor right away.

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What If BV Keeps Coming Back?

BV is frustratingly common—and recurrence is common too. About 30% of women experience recurrence within 3 months.

If BV keeps returning, your doctor may recommend:

• A longer course of metronidazole
• Maintenance vaginal gel therapy
• Evaluation for other infections
• STI testing
• Probiotics (in some cases)

Recurrent BV does not mean you've done anything wrong. It's a complex condition involving vaginal bacteria balance.

If you're unsure whether your symptoms are BV or something else, Ubie's free AI-powered Bacterial Vaginosis symptom checker can help you understand your symptoms and guide your next steps before seeing a doctor.

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Metronidazole and Sexual Activity

For BV:

• You can have sex during treatment, but it may worsen irritation
• Condoms may reduce recurrence risk
• Avoid douching (this disrupts healthy bacteria)
• Female partners may need evaluation in some cases

For trichomoniasis:

• Both partners must be treated
• Avoid sex until treatment is complete

Always follow your healthcare provider's instructions.

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Metronidazole and Pregnancy

Metronidazole is often considered safe during pregnancy, especially after the first trimester. In fact, treating BV during pregnancy can reduce certain risks like:

• Preterm birth (in some high-risk women)
• Infection complications

If you are pregnant or trying to conceive, inform your provider before starting medication.

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Does Metronidazole Cause Yeast Infections?

Sometimes.

Because metronidazole changes vaginal bacteria, it can occasionally allow yeast to overgrow. Signs of a yeast infection include:

• Thick white discharge
• Intense itching
• Redness and swelling
• Burning during urination

If these symptoms appear after treatment, speak to your doctor. A simple antifungal medication can treat it.

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Tips for Taking Metronidazole Safely

To reduce side effects and improve effectiveness:

• Take oral tablets with food to reduce nausea
• Avoid alcohol
• Complete the full course
• Do not double doses if you miss one
• Store medication properly
• Tell your doctor about other medications

Metronidazole can interact with certain drugs, including blood thinners and some seizure medications.

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When to Speak to a Doctor

While BV itself is usually not life-threatening, untreated infections can increase risk for:

• Pelvic inflammatory disease (PID)
• STI transmission
• Pregnancy complications

Speak to a doctor if:

• Symptoms don't improve after treatment
• Symptoms return quickly
• You have pelvic pain or fever
• You're pregnant and experiencing symptoms
• You develop severe side effects
• You have new sexual partners and want STI screening

If anything feels severe, worsening, or potentially life-threatening, seek urgent medical care immediately.

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The Bottom Line

Metronidazole is a highly effective and widely trusted treatment for bacterial vaginosis and other infections in women. Most women tolerate it well, and relief often begins within a few days.

Key things to remember:

• Finish the full course
• Avoid alcohol
• Expect mild side effects
• Follow up if symptoms return
• Speak to a doctor about serious concerns

If you're experiencing unusual symptoms and want to better understand what might be causing them, try Ubie's free online Bacterial Vaginosis symptom checker to get personalized insights before your doctor's appointment.

Your health matters. Don't ignore persistent symptoms—and don't hesitate to speak to a doctor about anything that feels serious, worsening, or life-threatening. Early treatment leads to better outcomes and peace of mind.