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Alcohol Intolerance: Symptoms, Causes & Testing

Last Updated: November 15, 2023

Editorial Policy | Research Policy

Alcohol intolerance is a physical reaction to alcohol that can cause mild to severe side effects, even with minimal alcohol consumption. 

Alcohol, for many, can be a way to unwind and socialize with others. However, even a small sip can lead to an unpleasant reaction for some people. If you’ve ever experienced facial flushing, nausea or a rapid heartbeat after drinking, you might have alcohol intolerance. Understanding what alcohol intolerance is, its causes, symptoms and how to test for it can help if you’re experiencing unpleasant symptoms after using alcohol.

What Is Alcohol Intolerance?

Alcohol intolerance is a condition where you experience a reaction after consuming alcohol. It’s not the same as getting drunk or having a hangover; it’s a physical reaction to alcohol that can occur even with minimal consumption. The symptoms can range from mild to severe and are often mistaken for other conditions. 

Alcohol Allergy vs. Intolerance

While the terms “alcohol allergy” and “alcohol intolerance” are sometimes used interchangeably, they are distinct and separate conditions. An alcohol allergy is a somewhat uncommon condition where the immune system reacts to the ingredients in alcohol, similar to how some people are allergic to peanuts or shellfish. Alcohol allergy is often not truly an allergy to alcohol itself but rather an allergy to something in the alcoholic beverage.

Alcohol intolerance, on the other hand, is a metabolic problem where the body lacks an enzyme needed to break down alcohol, leading to a build-up of chemicals that cause unpleasant symptoms. Alcohol intolerance is due to alcohol itself and is not something that can be avoided by using a different type of alcoholic beverage. It’s crucial to differentiate between alcohol intolerance and alcohol allergy, as the management and implications of each are different.

Causes of Alcohol Intolerance

Alcohol intolerance is caused when an enzyme called aldehyde dehydrogenase (ALDH2) doesn’t work correctly. Often, it is due to a deficiency of the enzyme; however, it can also be due to inhibition of the enzyme. When this enzyme isn’t present and working, the body struggles to break down alcohol, accumulating toxic byproducts. Some other causes include:

  • Genetic factors: Some populations, especially those of East Asian descent, have a higher prevalence of ALDH2 deficiency.
  • Medications: Certain drugs can interfere with alcohol metabolism, leading to intolerance.
  • Certain diseases: Some diseases, such as certain types of cancer, have alcohol intolerance as a rare side effect.

How Does Sudden Onset Alcohol Intolerance Occur?

It can be perplexing when you develop alcohol intolerance seemingly out of the blue. While genetics can play a significant role in alcohol intolerance, it will be present your entire life and not start suddenly. Other factors like health conditions, medications or even aging can lead to a sudden onset. Medications are the most common culprit, with disulfiram and metronidazole often leading to a sudden onset of alcohol intolerance.

Symptoms of Alcohol Intolerance

If you suspect you have alcohol intolerance, watch out for the following symptoms after consuming alcohol:

  • Flushed skin
  • Stomach upset
  • Rapid heartbeat
  • Nasal congestion
  • Headaches

These symptoms are typically unpleasant, not dangerous. If they are caused by alcohol intolerance, they will begin very soon after drinking alcohol and occur every time you drink.

Alcohol Intolerance Testing

If you believe you have alcohol intolerance, you should consult a healthcare professional. Some genetic tests can determine if your genes affect the ALDH2 enzyme. Alcohol intolerance, however, is typically diagnosed by ruling out other causes of your symptoms, such as alcohol allergy, and based on the nature of your symptoms.

Can Alcohol Intolerance Be Treated?

There’s no cure for alcohol intolerance, and the best way to manage it is to avoid or limit alcohol consumption. Depending on the cause, alcohol intolerance can sometimes be eliminated by addressing the underlying cause. While drinking with an alcohol intolerance is not recommended, some medications can help mask symptoms. Choosing to drink with an alcohol intolerance will be unpleasant and dangerous over the long term, as the frequent build-up of acetaldehyde in your blood can increase your risk of cancer.

If you are struggling to stop drinking even though you have alcohol intolerance, you should consider getting professional help to stop drinking alcohol. At The Recovery Village Kansas City, we understand how difficult it can be to stop using alcohol and what it takes to defeat alcohol addiction. Contact us today to learn more about how we can help you start on your journey to lasting recovery.


MedlinePlus. “​​Alcohol.” March 22, 2022. Accessed October 5, 2023.

Mayo Foundation for Medical Education and Research. “Alcohol Intolerance.” April 6, 2023. Accessed October 5, 2023.

Genetic and Rare Diseases Information Center. “Acute alcohol sensitivity.” February, 2023. Accessed October 5, 2023.

National Institute on Alcohol Abuse and Alcoholism. “Alcohol’s Effects on Health.” September, 2022. Accessed October 5, 2023.

Australasian Society of Clinical Immunology and Allergy. “Alcohol Allergy.” March, 2019. Accessed October 5, 2023.