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Metronidazole is a common antibiotic often sold under the brand name Flagyl. It’s also available as a generic drug. It’s most commonly prescribed as an oral tablet, and it also comes as a vaginal suppository and a topical cream. It is widely used for a variety of bacterial infections.

It’s also no myth that you shouldn’t combine it with alcohol.

On its own, metronidazole can cause the following side effects:

These can be unpleasant, but drinking alcohol within three days of taking metronidazole can cause additional unwanted effects, too. The most common is face flushing (warmth and redness), but other possible effects include:

Further, mixing metronidazole with alcohol can cause severe side effects. These include a sudden drop in blood pressure, rapid heart rate, and liver damage.

Metronidazole can treat certain infections caused by bacteria. These include bacterial infections of your:

You usually take this drug up to three times per day for 10 days, depending on the type of infection.

People taking antibiotics sometimes feel better before they’ve taken all of their medication. It is important to take all of your antibiotics, unless your doctor tells you otherwise. Not finishing your antibiotic medication as directed can contribute to bacterial resistance and make the drug less effective. For this reason, you also shouldn’t stop taking this antibiotic early so that you can drink.

To stay safe, you should also make sure your doctor knows about all of the medications you take, including over-the-counter and prescription drugs, vitamins, and herbal supplements. You should also tell your doctor if you’re pregnant or thinking about becoming pregnant.

Besides alcohol, there are other items to consider if you use metronidazole:

Use of blood thinners: Metronidazole can increase the effectiveness of blood thinners such as warfarin. This can increase your risk of abnormal bleeding. If you take a blood thinner, your doctor may need to decrease its dose while you take this drug.

Existing kidney or liver disease: Metronidazole can be hard on your kidneys and liver. Taking it while you have kidney or liver disease can make these diseases even worse. Your doctor may need to limit your dose or give you a different drug.

Existing Crohn’s disease: Taking metronidazole can complicate Crohn’s disease. If you have Crohn’s disease, your doctor may adjust your dose of metronidazole or prescribe a different drug.

Sun exposure: Taking metronidazole can make your skin especially sensitive to the sun. Make sure to limit sun exposure while you take this drug. You can do this by wearing hats, sunscreen, and long-sleeved clothing when you go outside.

Shop for sunscreen.

It is best to avoid alcohol while taking metronidazole. Alcohol can cause reactions in addition to the regular side effects of this drug. Some of these reactions can be severe. The typical length of treatment with this drug is only 10 days, and it’s best to wait at least three more days after your last dose before reaching for a drink. In the scheme of things, this treatment is short. Waiting it out before drinking could save you a good deal of trouble.