How To Use Metronidazole

How to Take Metronidazole: Step-by-Step Usage Guide

1. Check suitability: Read the patient information leaflet. Ensure you have no allergies to metronidazole or other nitroimidazoles (like tinidazole).
2. Prepare a glass of water: Have a full glass of water ready to swallow the tablet.
3. Take with food: Swallow the tablet whole during or just after a meal. This reduces the chance of feeling sick.
4. Do not crush or chew: Tablets have a bitter taste and are designed to be swallowed whole.
5. Follow the timing: Space doses evenly – usually every 8 hours. Use an alarm if needed.
6. Complete the course: Keep taking until you finish all tablets, even if symptoms disappear.
7. Avoid alcohol: Do not drink any alcohol during treatment and for 48 hours after the last dose.

Dosage Guide for Adults & Children

Dosage depends on the type of infection, your age, kidney/liver function, and the formulation. Below are general guidelines from the PIL.

Adults – Bacterial infections

• Initial dose: 800mg (two 400mg tablets) as a single dose.
• Maintenance dose: 400mg every 8 hours (usually for 5–7 days).

Surgical infection prevention

• Start 24 hours before surgery: 400mg every 8 hours.
• After surgery, you may receive intravenous or suppository metronidazole until you can swallow tablets.

Children

• Dose is calculated by the doctor based on your child's weight.
• For babies under 8 weeks: usually one daily dose or two doses 12 hours apart.

Special adjustments

• Liver problems: Lower dose or less frequent dosing may be needed.
• Kidney dialysis: Take the dose after dialysis session.

Who Should Use Metronidazole?

Metronidazole is prescribed for people with proven or suspected anaerobic bacterial infections or certain parasitic infections. Common conditions include:

• Bacterial vaginosis (BV)
• Pelvic inflammatory disease (usually with other antibiotics)
• Dental infections (acute ulcerative gingivitis, pericoronitis)
• Infected leg ulcers and pressure sores
• Intra-abdominal infections (e.g., diverticulitis, appendicitis)
• Brain abscess (with other antibiotics)
• Prevention of post-surgical infections (colorectal, gynaecological)

Your doctor will decide if metronidazole is right for your specific infection.

Who Should NOT Use Metronidazole?

• Allergy: If you are allergic to metronidazole, other nitroimidazoles (tinidazole), or any tablet ingredients.
• First trimester of pregnancy: Generally avoided unless absolutely necessary – discuss with your doctor.
• Severe liver disease: Dose adjustment required; in some cases, alternative antibiotics may be preferred.
• Active neurological disorders: Such as epilepsy or peripheral neuropathy – metronidazole can worsen these.
• Cockayne syndrome: These patients are at high risk of severe liver toxicity; metronidazole should be avoided or used with extreme caution and frequent monitoring.
• If you are taking disulfiram (for alcohol dependence): Combining can cause psychosis; wait at least two weeks after stopping disulfiram.

To Be Taken With Food or Without Food?

Take metronidazole with or just after food. This helps reduce nausea and stomach upset, which are common side effects. Food does not significantly reduce absorption, so you get the full benefit. If you forget to take it with a meal, you can take it with a snack or a glass of milk.

Avoid taking it on an empty stomach if you are prone to nausea.

Special Conditions: Pregnancy, Breastfeeding & More

Pregnancy

Metronidazole crosses the placenta. It is generally avoided in the first trimester unless the benefit outweighs the risk. For BV in pregnancy, topical treatments (gels or creams) are often used first. Always inform your doctor if you are pregnant or planning pregnancy.

Breastfeeding

Small amounts of metronidazole pass into breast milk. The manufacturer advises either stopping breastfeeding or avoiding the drug. A single high dose (2g) is not recommended while breastfeeding. For short courses, your doctor may advise pumping and discarding milk during treatment and for 24 hours after the last dose. Discuss with your healthcare provider.

Liver impairment

Dose reduction may be needed; your doctor will monitor liver function.

Kidney dialysis

Take metronidazole after dialysis, as the treatment removes the drug.

Elderly

Standard dosing is usually appropriate, but kidney and liver function should be considered.

Metronidazole Usage FAQs

Need Metronidazole Prescription?

If you have symptoms of bacterial vaginosis or another infection, speak to a UK-registered doctor online.

Secure Prescription & Next-Day Delivery

MHRA-compliant | GPhC-registered pharmacy | Discreet packaging | UK doctors