Alcohol intolerance is not normally dangerous. However, it is unpleasant enough that most people who have it will avoid heavy amounts of alcohol.

Alcohol intolerance1 is a rare condition that causes people to experience unpleasant symptoms when drinking alcohol. This condition can cause many symptoms, but a stuffy nose and flushing in the face are the most common. 

Alcohol intolerance is not normally dangerous. However, it is unpleasant enough that most people who have it will avoid heavy amounts of alcohol.

What Is Alcohol Intolerance?

Alcohol intolerance is an uncommon condition that affects an enzyme involved in alcohol metabolism. Alcohol in your body turns into a chemical called acetaldehyde2, which is then immediately broken down into another chemical called acetate. 

People with alcohol intolerance have a mutation in the enzyme that breaks acetaldehyde down into acetate, causing the acetaldehyde to build up in the body. Over the long term, acetaldehyde can increase the risk of cancer. On a short-term basis, it will only cause the unpleasant symptoms that alcohol intolerance is known for.

Alcohol Allergy vs. Intolerance

Alcohol intolerance is different from an alcohol allergy3. Alcohol intolerance happens because a defective enzyme causes acetaldehyde to build up. Alcohol allergy occurs when the body’s immune system overreacts to alcohol. People may also have allergies to other components of an alcoholic drink, such as an ingredient in a mixer, and mistake this for an alcohol allergy. Still, either condition will cause unpleasant symptoms to occur when drinking alcohol.

What Causes Alcohol Intolerance?

Alcohol intolerance is caused by an abnormality in an enzyme called aldehyde dehydrogenase. This abnormality is caused by genetics4, meaning that people with alcohol intolerance inherited the genetic trait from at least one of their parents. Alcohol intolerance can be more common in people of Asian descent.

Alcohol Intolerance Symptoms

Alcohol intolerance symptoms are caused by the buildup of acetaldehyde that occurs as alcohol is metabolized. Symptoms of alcohol intolerance5 can include:

  • Facial redness
  • Worsening of existing asthma
  • Runny or stuffy nose
  • Diarrhea
  • Nausea or vomiting
  • Low blood pressure
  • Headache
  • Hangover symptoms
  • Heart palpitations
  • Low blood pressure 

Alcohol Flushing

Alcohol intolerance is sometimes called “Asian Flush”6 because it primarily affects those of Asian descent and the main symptom is flushing in the face. This flushing (sudden redness) is caused by the buildup of acetaldehyde. Facial flushing after drinking alcohol is a strong indicator that alcohol intolerance may be present.

Sudden Alcohol Intolerance

While alcohol intolerance is normally caused by genetics, several other factors can also cause it to develop. Some cancers7 have been found to suddenly cause alcohol intolerance, likely due to an effect on how acetaldehyde is processed.

Medications can also cause alcohol intolerance. The antibiotic metronidazole temporarily affects how the enzyme aldehyde dehydrogenase works, causing alcohol intolerance. Disulfiram is another medication that causes alcohol intolerance, but it is taken to deliberately cause alcohol intolerance. The purpose of this medication is to discourage drinking in those who find it difficult to stop. By creating an alcohol intolerance, the appeal of alcohol is greatly reduced. Disulfiram can be used as part of alcohol addiction treatment.

Alcohol Intolerance Test

Alcohol intolerance is normally diagnosed based on the symptoms that are experienced. Allergy testing8 may be done to rule out an alcohol allergy. While there are no specific tests for alcohol intolerance, genetic testing can indicate whether you have the genetics associated with alcohol intolerance. These approaches can help determine if alcohol intolerance is present. 

Living With Alcohol Intolerance

Someone who does not use alcohol won’t usually know that they have an alcohol intolerance; this condition is only ever an issue when alcohol is used. For those who do enjoy alcohol, however, it can be more difficult. There is normally no way to get rid of alcohol intolerance. 

One important consideration for those with alcohol intolerance is exposure to alcohol in unexpected places. For example, drinking a cough syrup that has alcohol can cause a reaction in someone who has alcohol intolerance. Alcohol intolerance requires mindfulness about potential exposures to alcohol.

Alcohol Intolerance Treatment

Unless it is caused by the use of a medication, there is no cure for alcohol intolerance. Alcohol intolerance will be present for life, and there is no way to get rid of it. Someone with alcohol intolerance may be able to take medications that mask the symptoms, but these medicines will not deal with the underlying issue.

Someone with alcohol intolerance may still be able to develop an addiction to alcohol if they push through the unpleasant symptoms. This can be dangerous, as prolonged exposure to high acetaldehyde levels can increase the risks of several types of cancers.

If you or someone you love is struggling with alcohol use, The Recovery Village at Cherry Hill can help you achieve lasting sobriety. Contact us today to learn more about alcoholism treatment programs that can support you in living a healthier, alcohol-free life. 

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Editor – Jonathan Strum
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Medically Reviewed By – Benjamin Caleb Williams, RN
Benjamin Caleb Williams is a board-certified Emergency Nurse with several years of clinical experience, including supervisory roles within the ICU and ER settings. Read more

  1. National Center for Advancing Translational Sciences. “Acute alcohol sensitivity.” Accessed January 28, 2022.
  2. Delaware Health and Social Services. “Acetaldehyde.” January 2015. Accessed January 28, 2022.
  3. Australasian Society of Clinical Immunology and Allergy. “Alcohol Allergy.” March 2019. Accessed January 28, 2022.
  4. Morozova, Tatiana V.; Mackay, Trudy F.C.; Anholt, Robert R.H. “Genetics and genomics of alcohol sensitivity.” Molecular Genetics and Genomics, 2014. Accessed January 28, 2022.
  5. Igumnova, Anastasia. “Alcohol Flush Reaction: Do You Have Alcohol Intolerance?” Atlas Blog. Accessed January 28, 2022.
  6. Brooks, Philip J.; Enoch, Mary-Anne; et al. “The Alcohol Flushing Response: An Unreco[…] Alcohol Consumption.” PLoS Medicine, March 2009. Accessed January 28, 2022.
  7. Bryant, Andrew J.; Newman, John H. “Alcohol intolerance associated with Hodgkin lymphoma.” CAMJ, May 14, 2013. Accessed January 28, 2022.
  8. Wüthrich, B. “Allergic and intolerance reactions to wine.” Allergologie Select, September 2018. Accessed January 28, 2022.
Medical Disclaimer

The Recovery Village aims to improve the quality of life for people struggling with a substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare provider.