Introduction
Metronidazole is a prescription antibiotic used to treat infections caused by bacteria and certain parasites. It is commonly prescribed for stomach infections, vaginal infections, dental infections, and skin conditions like rosacea.
This guide explains what metronidazole treats, how to take it safely, common side effects, and important warnings patients should know.
What Is Metronidazole?
Metronidazole belongs to a group of medicines called nitroimidazole antibiotics. It works by damaging the DNA of harmful microorganisms, stopping them from growing and spreading.

It is available as:
- Oral tablets and capsules
- Topical cream or gel
- Vaginal gel
- IV injection (hospital use)
Metronidazole Uses
Doctors prescribe metronidazole to treat infections caused by anaerobic bacteria and parasites.
1. Bacterial Vaginosis
A common vaginal infection caused by bacterial imbalance.
2. Parasitic Infections
- Giardiasis
- Amebiasis
- Trichomoniasis (sexually transmitted infection)
3. Gastrointestinal Infections
Treats certain stomach and intestinal infections that cause severe diarrhea.
4. Dental Infections
Used for gum infections, tooth abscesses, and oral surgery infections.
5. Skin Conditions
Topical metronidazole helps reduce inflammation in rosacea.
Metronidazole Dosage
Dosage depends on the condition and patient health.
- Tablets: Usually 1โ3 times daily for 5โ10 days
- Topical forms: Apply once or twice daily
- Vaginal gel: Typically once daily for 5 days
Important: Always complete the full course even if you feel better.
Common Side Effects of Metronidazole
- Nausea
- Metallic taste in mouth
- Headache
- Loss of appetite
- Stomach upset
- Diarrhea
These side effects are usually mild and temporary.
Serious Side Effects (Seek Medical Help)
- Seizures
- Numbness or tingling
- Severe allergic reaction
- Persistent vomiting
- Severe dizziness
Important Safety Warnings
Avoid Alcohol
Do not drink alcohol during treatment and for at least 48 hours after finishing. Mixing alcohol with metronidazole can cause severe nausea, vomiting, flushing, and rapid heartbeat.
Pregnancy and Breastfeeding
Consult your healthcare provider before use.
Drug Interactions
Metronidazole may interact with blood thinners, lithium, and certain seizure medications. Always share your full medication list with your provider.
Tips for Taking Metronidazole Safely
- Take doses at the same time each day
- Take with food if stomach upset occurs
- Do not skip doses
- Do not share antibiotics
- Store at room temperature
When to See a Doctor
- Symptoms do not improve within a few days
- Side effects become severe
- Infection returns after treatment
Frequently Asked Questions
How fast does metronidazole work?
Most patients notice improvement within a few days, but the full course must be completed.
Can metronidazole treat viral infections?
No. It does not work for colds or flu.
Is metallic taste normal?
Yes, it is a common temporary side effect.
Medical Disclaimer
This information is for educational purposes only and does not replace professional medical advice. Always follow instructions from your healthcare provider.
Credible Health References
Safety and antibiotic guidance from Centers for Disease Control and Prevention and drug safety labeling from U.S. Food and Drug Administration support the recommendations summarized in this guide.
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