Metronidazole: Why You Must Avoid Alcohol With This Antibiotic

What metronidazole is

Metronidazole is an antibiotic that is also effective against certain parasites. It works particularly well against bacteria that thrive in low-oxygen environments, known as anaerobes, which makes it useful for infections that other antibiotics struggle to reach. It is a prescription-only medicine in the UK and EU.

What it is used for

Doctors may prescribe metronidazole for infections including:

• Some dental and gum infections
• Certain gut and abdominal infections
• Some skin and wound infections
• Particular vaginal and pelvic infections
• Some parasitic infections

Like all antibiotics, it targets bacteria (and some parasites) only and has no effect on viruses. Appropriate use supports the wider effort against antibiotic resistance explained. For more background, see bacterial infections explained.

The alcohol warning — read this carefully

The single most important practical point about metronidazole is its interaction with alcohol. Combining the two can cause an unpleasant reaction that may include:

• Flushing and a hot, red face
• Nausea and vomiting
• Headache
• A fast or pounding heartbeat
• Stomach cramps

For this reason, you should avoid all alcohol while taking metronidazole and for a period after finishing the course — the leaflet will state how long, often a couple of days. This includes hidden sources of alcohol such as some mouthwashes, tonics and certain cold and flu remedies, so check labels. If you are unsure, ask your pharmacist.

How to take it safely

Follow your prescriber's directions and the patient information leaflet. General guidance includes:

• Finish the full course even if you feel better, to clear the infection completely and reduce resistance.
• Take it with or after food if it upsets your stomach, unless told otherwise.
• Swallow tablets whole with water.
• Tell your doctor about other medicines, especially blood-thinners such as warfarin.

Metronidazole may give some people a metallic taste in the mouth or darken the colour of their urine. These effects are generally harmless and settle after the course.

Possible side effects

Common side effects include nausea, a metallic taste, loss of appetite and stomach upset. Most are mild. Seek medical advice promptly if you experience severe or ongoing diarrhoea, numbness or tingling in the hands or feet, or signs of an allergic reaction such as a rash, swelling or breathing difficulty.

Contraception and other practical points

Metronidazole is not generally thought to reduce the effectiveness of the contraceptive pill on its own, but vomiting or severe diarrhoea during any antibiotic course can. If that happens, use backup contraception and ask your pharmacist. Always mention pregnancy or breastfeeding to your prescriber, as advice may differ.

When to see a doctor

Contact your doctor if your symptoms do not improve, get worse, or return after treatment, or if you accidentally drink alcohol and feel very unwell. You can browse our antibiotics range, compare with the Amoxicillin guide, or shop all for everyday health needs.

Metronidazole is a reliable antibiotic for the right infections. Remember the golden rule: no alcohol during the course and for the advised time afterwards.

General information only — not medical advice. Always read the patient information leaflet and consult a doctor or pharmacist before starting any medication.