Metronidazole – Specialized antibiotic for anaerobic bacteria and parasites.
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What is Metronidazole?
Metronidazole is a specialized antibiotic that’s particularly effective against anaerobic bacteria and certain parasites. It’s commonly used for infections in areas of the body with low oxygen levels, such as the mouth, gut, and reproductive organs.
Book an online consultation if you’re experiencing symptoms of bacterial infections, particularly dental infections, digestive problems, or gynecological infections. Our GPs can assess your symptoms and determine if Metronidazole is the appropriate antibiotic for your specific condition.
What is Metronidazole used for?
- Bacterial vaginosis and trichomonas infections
- Helicobacter pylori eradication (with other medications)
- Dental and gum infections
- Skin and soft tissue infections
- Inflammatory bowel disease (Crohn's disease)
- Post-surgical infection prevention
- Amoebic dysentery and giardiasis
- Anaerobic bacterial infections
How does Metronidazole work?
An antimicrobial agent that disrupts DNA synthesis in bacteria and parasites, particularly effective against anaerobic organisms that thrive in low-oxygen environments.
Dosage and Administration
Adults
200-500 mg taken 2-3 times daily for 5-10 days, depending on infection type.
Children
7.5 mg per kg taken 3 times daily—GP will calculate appropriate dose based on weight.
Important Notes
- Take with or after food to reduce stomach upset.
- Complete the full course even if symptoms improve.
- Avoid alcohol completely during treatment and for 48 hours after.
- Take at evenly spaced intervals throughout the day.
Side Effects
Common Side Effects
- Metallic taste in mouth
- Nausea and vomiting
- Loss of appetite
- Diarrhoea or constipation
- Stomach cramps
- Headache
- Dizziness
Serious Side Effects
Seek immediate medical attention if you experience:
- Peripheral neuropathy (numbness in hands/feet)
- Severe allergic reactions
- Seizures (rare)
- Blood disorders
- Severe liver problems
- Stevens-Johnson syndrome (severe skin reaction)
Important Warnings
- NEVER drink alcohol during treatment—can cause severe reaction with flushing, nausea, and vomiting.
- Tell your GP if you have liver disease, blood disorders, or neurological conditions.
- May worsen existing nerve problems—report any numbness or tingling.
- Can interact with warfarin—increased bleeding risk.
- May cause dark urine—this is usually harmless.
Drug Interactions
Tell your GP if you're taking any of the following medications:
- Alcohol—dangerous reaction causing severe nausea and flushing.
- Warfarin—significantly increases bleeding risk.
- Lithium—may increase lithium levels and toxicity.
- Phenytoin—may increase phenytoin levels.
- Disulfiram—may cause confusion and psychotic reactions.
- Ciclosporin—may increase ciclosporin levels.
Frequently Asked Questions
Why can't I drink alcohol with Metronidazole?
Metronidazole blocks alcohol metabolism, causing a 'disulfiram-like reaction' with severe nausea, vomiting, flushing, and rapid heart rate. Avoid alcohol completely.
How long does the metallic taste last?
The metallic taste usually appears within 1-2 days of starting treatment and typically resolves within a few days of completing the course.
Why is my urine darker than usual?
Metronidazole can cause harmless darkening of urine. This is a normal side effect and will resolve after completing treatment.
Can I use Metronidazole gel for vaginal infections?
Yes, topical Metronidazole gel is available for bacterial vaginosis. It has fewer systemic side effects than oral tablets.
Medically Reviewed by: Mohammed Hassan - Independent Prescriber
Last Updated: 2025-01-14