Metronidazole and Alcohol: Is It Safe?

Bacterial vaginosis (BV) is a common infection affecting around 23 to 29% of reproductive-age women. It’s caused by an imbalance of vaginal bacteria and the main symptom is unusual vaginal discharge. Bacterial vaginosis can increase the risk of getting a sexually transmitted infection, but treatment is available.

Metronidazole tablets are the first-line treatment for bacterial vaginosis. They contain metronidazole, an antibiotic that kills BV-causing bacteria. Some studies show that metronidazole is more than 90% effective for treating BV. However, there are some concerns about drinking alcohol while taking metronidazole because it can cause a reaction, often referred to as a ‘disulfiram-like’ reaction.

In this guide, we’ll discuss why you should avoid drinking alcohol while taking metronidazole, the potential side effects, and how long you’ll need to wait after you finish your course to drink alcohol again.

Drinking alcohol while taking metronidazole is not recommended because it can cause a reaction in some people called a disulfiram-like reaction (DLR). Disulfiram is a type of medication given to help people with chronic alcoholism stop drinking alcohol.

When alcohol and metronidazole mix, it can cause side effects like:

• feeling and being sick
• stomach pain
• palpitations
• headache

Metronidazole and alcohol cause a DLR because metronidazole impacts how your body metabolises (processes and breaks down) alcohol, causing a buildup of the toxic by-product, acetaldehyde.

Usually, when you drink alcohol, your body breaks it down or metabolises it in 2 stages:

1. Alcohol is broken down into acetaldehyde, a toxic compound that causes alcohol-related side effects like feeling or being sick and flushing.
2. Acetaldehyde is then reduced to acetate by an enzyme called aldehyde dehydrogenase. Acetate is oxidised into carbon dioxide, which leaves the body when you breathe out.

Disulfiram blocks the effects of the enzyme aldehyde dehydrogenase, which causes acetaldehyde to build up in the body and cause symptoms like:

• flushing
• palpitations
• feeling or being sick
• headache

It was thought that metronidazole blocked the effect of this enzyme, causing similar symptoms, but the evidence for this is mixed.

What should you do if you drink while taking metronidazole?

If you drink alcohol while taking metronidazole, it can cause some unpleasant side effects, including feeling or being sick. You should monitor your symptoms and seek medical advice if you are concerned. We go into more detail on managing the side effects of drinking on metronidazole in the following section.

Like all medications, metronidazole can cause side effects, although not everyone will get them.

Common metronidazole side effects include:

• feeling sick (nausea)
• being sick (vomiting)
• diarrhoea
• metallic taste in your mouth or a furry tongue

If you drink alcohol while taking metronidazole, you may experience symptoms similar to a disulfiram-like reaction. In mild cases, these symptoms can be managed by:

If your symptoms are severe, you should seek urgent medical attention.

You should wait at least 48 hours or 2 days after finishing a course of metronidazole before drinking alcohol. The half-life of metronidazole (the time it takes for half of the medication to leave your body) is 8 hours. However, it can take 44 hours or more for it to completely leave your body.

If you have liver problems, it can take longer than 48 hours for metronidazole to fully leave your system, so it’s advisable in some cases to wait at least 72 hours after your last dose before drinking alcohol.

If you are unsure, you should speak to your doctor or pharmacist for advice.

If you have been prescribed metronidazole for bacterial vaginosis, it’s advisable not to drink alcohol or eat food containing alcohol for the duration of your course of antibiotics and for the 2 days after you take your final dose.

If you do consume alcohol while taking metronidazole, it can cause a reaction that results in several unpleasant symptoms.

Can I drink alcohol 24 hours before taking metronidazole?

Yes, you can drink alcohol 24 hours before taking metronidazole, but it’s advisable to stop drinking alcohol 12 hours before you start your first dose to avoid any potential interactions.

Can I have one drink while taking metronidazole?

No, it’s generally advisable not to drink any alcohol while taking metronidazole. If you drink alcohol, it can react with metronidazole and cause side effects like feeling and being sick, stomach pain, and a racing heartbeat.

What about alcohol in mouthwash and food?

For safety, you should avoid alcohol containing products, like mouthwash, and foods, because they may react with metronidazole and cause unpleasant side effects. Even small amounts of alcohol can cause side effects while taking metronidazole.

Can you drink alcohol while using metronidazole cream?

No, it is best to avoid all alcohol while using any metronidazole-containing product, including cream, to prevent interactions and side effects.

Can alcohol make BV worse?

Yes, alcohol may make bacterial vaginosis symptoms worse because it can change your vaginal microbiome, making you more susceptible to bacterial vaginosis bacteria. Equally, increased consumption of alcohol can lead to more risky sexual behaviours or a loss of inhibition, which can increase the risk of bacterial vaginosis.