Alcohol intolerance is a condition in which someone’s body is not able to process alcohol normally. This results in the buildup of a chemical called acetaldehyde, which causes uncomfortable symptoms that are typically considered to be worse than any pleasure that alcohol brings. 

Alcohol intolerance is relatively uncommon, and many people who have problems drinking alcohol actually have an alcohol allergy — not alcohol intolerance. If you believe you may be suffering from an alcohol allergy or intolerance, it can be helpful to learn about the symptoms of these two conditions.

What Is Alcohol Intolerance?

Alcohol intolerance occurs when someone has a disruption in the way that their body breaks down alcohol. Usually, alcohol is broken down into a chemical called acetaldehyde. This chemical is almost immediately converted into other chemicals by an enzyme called aldehyde dehydrogenase. A deficit or inhibition of this enzyme leads to alcohol intolerance and causes acetaldehyde to build up.

Prolonged acetaldehyde exposure can be harmful. However, the acetaldehyde buildup caused by alcohol intolerance does not last long enough to cause truly dangerous effects. Its temporary effects are still uncomfortable and can cause headache, nausea, stuffiness and other unpleasant symptoms.

Alcohol Allergy vs. Intolerance

Alcohol intolerance is quite uncommon, and many people who think they may have an intolerance to alcohol actually have an alcohol allergy. An alcohol allergy is very different from alcohol intolerance and occurs when the body’s immune system attacks something found in alcohol.

Alcohol allergies are almost never caused by the alcohol itself. More commonly, they are related to a component of the alcohol, such as grapes, hops or barley. Someone with an alcohol allergy may not be allergic to all forms of alcohol equally.

Alcohol Intolerance Symptoms

Alcohol intolerance symptoms are caused by the buildup of acetaldehyde in the bloodstream. These symptoms include:

  • Flushing in the face
  • Stuffy nose
  • Headache
  • Abdominal pain
  • Nausea or vomiting
  • Diarrhea

These symptoms occur almost immediately after using alcohol. They may even be caused by exposure to alcohol from sources other than alcoholic beverages. For example, using cough syrup with alcohol in it or even using an alcohol-based hand sanitizer can lead to alcohol intolerance symptoms.

What Causes Alcohol Intolerance?

There are several different things that can cause alcohol intolerance, including genetics. DNA changes affecting the enzyme aldehyde dehydrogenase will cause alcohol intolerance that will last throughout the lives of those who have it. People of Asian heritage most commonly have genetic-based alcohol intolerance; however, it can affect anyone.

Alcohol intolerance can also be caused by medications. Certain antibiotics can inhibit aldehyde dehydrogenase, leading to alcohol intolerance. In this situation, alcohol intolerance may be referred to as a disulfiram reaction. A medication called disulfiram (Antabuse) is actually used to deliberately cause this reaction, as it can help discourage people from drinking alcohol when they are trying to stop.

In addition, alcohol intolerance can be caused by certain diseases. While this most commonly occurs with Hodgkin’s lymphoma, a type of cancer, there are many diseases that can cause alcohol intolerance. However, only a small percentage of people with these diseases actually develop an alcohol intolerance.

What Causes a Sudden Alcohol Intolerance?

Sometimes, people who have previously been able to use alcohol may suddenly develop alcohol intolerance. This is usually caused by one of two things:  

  1. A medication that causes alcohol intolerance has been started. This is often related to an antibiotic called metronidazole (Flagyl), but other medicines may also cause this.
  2. It is not actually alcohol intolerance; rather, it is an alcohol allergy that has suddenly started. Allergies can develop suddenly and unpredictably.

Testing for Alcohol Intolerance

There is no specific test used to evaluate alcohol intolerance. However, genetic testing can determine whether you have the genes associated with lifelong, inherited alcohol intolerance. Testing for alcohol allergies can also help to rule out alcohol intolerance as a possibility.

The diagnosis of alcohol intolerance is usually made by ruling out alcohol allergy as a cause of these symptoms. It also involves evaluating the symptoms that occur and how connected they are to alcohol use.

Can Alcohol Intolerance Be Treated?

Alcohol intolerance cannot be eliminated if it is caused by genetics. While there are medicines that can reduce some of the symptoms of alcohol intolerance, they will still be present. Using alcohol when you have alcohol intolerance can lead to chronic acetaldehyde exposure; this is associated with health concerns such as an increased risk of cancer and other problems. Someone with genetic alcohol intolerance will generally be discouraged from ever using alcohol.

If alcohol intolerance is due to the use of a medication, it is much easier to treat. In these cases, alcohol should be avoided while taking the medicine, or the medicine should be changed. This should quickly resolve any problems caused by the medicine.

Best Alcohol for Alcohol Intolerance

Many people who have alcohol intolerance will wonder about what alcoholic drinks they can use. If it is a true alcohol intolerance, the amount of alcohol will be the sole factor that affects how a drink impacts you. Ultimately, it will be best to avoid alcoholic drinks and use non-alcoholic alternatives. If you choose to use alcohol, using lower-proof beverages is best.

If an alcohol intolerance is actually an alcohol allergy, then the best alcoholic beverages to use will be those that do not contain anything that you are allergic to. You may wish to consult with your doctor to help you figure out what drinks you are least likely to be allergic to.

If you or someone you love is struggling to stop drinking despite the unpleasant symptoms of alcohol intolerance, Orlando Recovery Center can help. Contact us today to learn more about alcohol abuse and addiction treatment programs that can work well for your needs.

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Editor – Jonathan Strum
Jonathan Strum graduated from the University of Nebraska Omaha with a Bachelor's in Communication in 2017 and has been writing professionally ever since. Read more
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

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Atlas Blog. “Alcohol Flush Reaction: Do You Have Alcohol Intolerance?” December 1, 2021. Accessed June 16, 2022.

Australasian Society of Clinical Immunology and Allergy. “Alcohol Allergy.” 2019. Accessed June 16, 2022.

National Organization for Rare Disorders. “NIH GARD Information: Acute alcohol sensitivity.” Accessed June 16, 2022.

Soghoian, Samara. “Disulfiram Toxicity.” Medscape, May 16, 2022. Accessed June 16, 2022.

Bryant, Andrew J.; Newman, John H. “Alcohol intolerance associated with Hodgkin lymphoma.” Canadian Medical Association Journal, May 14, 2013. Accessed June 16, 2022.

Medscape. “Metronidazole (Rx).” Accessed June 16, 2022.

YorkTest. “Alcohol Intolerance.” Accessed June 16, 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.