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What is Alcohol Intolerance?

Alcohol intolerance is sometimes referred to as acute alcohol sensitivity. It is characterized by an unpleasant and immediate reaction after drinking alcohol. The most typical signs and symptoms of acute alcohol sensitivity or alcohol intolerance are skin flushing and a stuffy nose. Alcohol intolerance is caused by a genetic condition in which the body cannot break down alcohol efficiently. Alcohol intolerance is not the same as alcohol intoxication.

Alcohol intolerance is most common in Asians [1]. Individuals who are suffering from acute alcohol sensitivity accumulate acetaldehyde, the primary metabolite of alcohol, because of a genetic polymorphism that doesn’t allow aldehyde dehydrogenase (ALDH) to metabolize acetaldehyde to non-toxic acetate.

The only way to prevent alcohol intolerance reactions is to avoid alcohol. Alcohol intolerance isn’t an allergy. However, in some cases, what seems to be alcohol intolerance may be a reaction to something in an alcoholic beverage, such as chemicals, grains, or preservatives. Combining alcohol with certain medications (Bactrim and alcohol) also can cause reactions. In rare instances, an unpleasant reaction to alcohol can signify a serious underlying health problem that requires diagnosis and treatment.

Alcohol Intolerance
Unfortunately, nothing can prevent reactions to alcohol or ingredients in alcoholic beverages. To avoid a reaction, avoid alcohol or the particular substance that causes your reaction.
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How Common is Alcohol Intolerance?

The existence of racial differences in alcohol sensitivity or alcohol intolerance between Oriental and Caucasian populations has been well documented [2]. The primary manifestation is a highly visible facial flushing (47-85% in Orientals vs 3-29% in Caucasians) accompanied by other objective and subjective symptoms of discomfort. Even among different Oriental groups, subtle differences in the flushing response and alcohol consumption can exist. 

North and South American Indian populations differ in phenotypes for alcohol dehydrogenase and aldehyde dehydrogenase, but systematic studies comparing the degree of flushing, alcohol elimination rates, and blood acetaldehyde levels in these populations are lacking. One study of 948 individuals found that 7.2% self-reported wine intolerance. It happened to women more than men (8.9% versus 5.2%). It is unclear if that number reflects the general population.

Aldehyde dehydrogenase (ALDH) is one of the two enzymes primarily involved in alcohol metabolism. Several variants exist of the gene that produces ALDH. One of these gene variants, which generates a nonfunctional enzyme, is present in Asians but not in Caucasians and African-Americans. People with two copies of the defective gene respond to alcohol consumption with intense flushing and other unpleasant reactions, such as nausea. Consequently, these people consume very little alcohol and are at a much lower risk for alcoholism than people with functional ALDH genes. 

Signs Your Body Might Be Alcohol Intolerant

If you’re a person who has severe reactions after one or two drinks, you may actually be alcohol intolerant. Symptoms differ from person to person, but there are some clear signs your body is intolerant to alcohol that you need to know about. It’s crucial to identify an alcohol intolerance, as it can have some severe long-term effects over time.

Flushed Face (Red Face)

Skin flushing is another extremely common symptom of intolerance. This might be caused by a rise in blood pressure due to the ALDH2 gene deficiency. When the body can’t break down acetaldehyde, that redness appears on the face and sometimes throughout the body.

Runny Nose

A stuffed or runny nose is one of the most common symptoms of alcohol intolerance. Nasal congestion is the result of inflammation in the sinus cavity. This is also due to high levels of histamine found in alcoholic beverages, especially wine and beer.


Alcohol intolerance can lead to warm, itchy bumps on the skin, also known as hives. This again is a result of an ALDH2 deficiency, but it can also be from histamines in your drink or allergies to specific ingredients.


It’s no surprise that alcohol intolerance can lead to feelings of nausea. This is attributed to an increase in stomach acid which irritates the esophagus, intestines, and stomach.


Along with nausea, vomiting can occur as well. Vomiting is also a sign of drinking too much, but if you feel that you immediately throw up from very few drinks, it’s likely a sign of intolerance.


This is common even for those who are not alcohol intolerant, but for those who are, it’s more severe and comes on quicker. When alcohol is consumed it affects how water is absorbed in the large intestine leading to more fluid and quicker stool passage.

Alcohol Intolerance
There are other possible conditions that may occur as primary or secondary effects due to the inability to break down alcohol. 

Fast Heart Beat

Alcohol intolerance can cause tachycardia or a fast heartbeat. A fast heart rate can also be a sign of a greater alcohol allergy, according to Livestrong, so if you experiencing a racing heart after drinking, it’s best to go see a doctor.

Worsening Of Asthma

Alcohol intolerance can cause worsening respiratory issues. If you have asthma, you can have an asthmatic reaction at that moment.

Low Blood Pressure

It’s not something you might be able to tell on your own, but an alcohol intolerance can cause a drop in blood pressure after drinking. Some indicators that your blood pressure has dropped include dizziness, lack of concentration, fatigue, rapid shallow breathing, and more.

When in doubt, it’s best to cut back on the alcohol, but also be sure to see a doctor, who can help you come up with the correct diagnosis.

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Alcohol Intolerance Symptoms 

Symptoms of alcohol intolerance include:

  • Facial redness (flushing)
  • Red and itchy skin bumps (hives)
  • Nasal congestion
  • Worsening of preexisting asthma conditions
  • Low blood pressure
  • A fluttering of the heart
  • Hot flashes
  • Nausea and vomiting
  • headaches and hypertension
  • Swelling of the lips or tongue
  • Coughing
  • Fainting or chest pain
  • Runny or stuffy nose
  • Diarrhea

By definition, the lack of enzymes within the body is the reason for alcohol intolerance. However, since symptoms can present very similarly, it is common for people to confuse alcohol intolerance with an alcohol allergy.

What Causes Alcohol Intolerance? 

Having an alcohol intolerance is a genetic condition that means the body can’t process alcohol efficiently. With this condition, a person has an inactive or less-active form of the chemical that breaks down alcohol in the body.

When someone drinks alcohol, the liver first breaks down alcohol into a toxic chemical called acetaldehyde. The body uses a chemical called aldehyde dehydrogenase, or ALDH2, to break down acetaldehyde. When broken down, acetaldehyde can’t hurt the body. However, in some individuals, ALDH2 does not work properly, resulting in alcohol intolerance.

Physicians have found that a problem with ALDH2 (the enzyme that helps break down the byproduct of alcohol) is genetic. Therefore, it is likely that your family members are at risk for the same problem. The main risk factors for having a problem with ALDH2 is being of East Asian descent, especially Chinese, Korean or Japanese.

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What Happens When You Drink Alcohol? 

This is what happens when a person consumes an alcoholic beverage:

  1. When someone drinks alcohol, the body uses an enzyme called alcohol dehydrogenase (ADH) to break down the alcohol.
  2. The liver then converts it to acetaldehyde which can be damaging for the body. This is where ALDH2 comes in.
  3. ALDH2 works by turning acetaldehyde into acetic acid, otherwise known as vinegar, which is safe for your body.
  4. When the ALDH2 enzyme is inactive or less active, the body doesn’t do a proper job at making this final conversion, resulting in the symptoms you experience if you have alcohol intolerance. 

Even in individuals who don’t have alcohol intolerance, a build of acetaldehyde in the body is what causes a person to feel sick when they’ve had too much alcohol. 

It can be difficult to diagnose conditions that are genetically inherited. In trying to make a diagnosis, your healthcare provider will look into the medical history and conduct a physical exam. The doctor might also conduct lab tests.

Diseases that Cause Alcohol Intolerance

Bad reactions to alcohol and alcohol intolerance can also characterize some diseases. However, just because you feel ill after drinking alcohol doesn’t mean you’re sick. If you have any concerns about your health, always consult a doctor.

  • Hodgkin lymphoma alcohol reaction: research shows that 1.5–5% of people with this cancer have a sudden onset alcohol intolerance that causes pain after ingesting alcohol.
  • Tumors of female organs: studies show that women with uterine tumors are more susceptible to alcohol reactions, followed by ovary and breast tumors.
  • Gilbert’s syndrome and alcohol intolerance: patients with this mild, hereditary liver condition may find that drinking alcohol causes brain fog, fatigue, jaundice, and severe hangovers.
  • Menopause and alcohol intolerance: drinking has been shown to worsen the symptoms of menopause by intensifying hot flushes and night sweats.

Alcohol Allergy vs. Intolerance

To an Allergist (a doctor who is an expert in the treatment of allergies), an “allergy” means that you have specific allergic antibodies or “IgE” to something like peanut, cat, or penicillin. True IgE-mediated allergy to alcohol is rare, but alcohol intolerance is quite common. Alcohol acts as a substance that causes the blood vessels in your skin and nasal passages to open up (vasodilator). This causes facial flushing (red face) and sometimes even itching or heat and nasal congestion.

For individuals with rosacea, this effect on the skin can be very brisk and alarming, which mimics an allergic reaction but is not associated with the other signs and symptoms of anaphylaxis (hives, angioedema, bronchospasm, hypotension). Some individuals are sensitive to certain kinds of alcohol and can develop gastrointestinal symptoms such as nausea, vomiting, diarrhea, or headaches even if they have not had a significant amount of alcohol.

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Alcohol Intolerance Treatment 

While there is no way to treat this condition, your doctor can talk with you about reducing the adverse effects of alcohol intolerance. You may need to avoid:

  • Alcohol: Avoiding or restricting alcohol consumption is the most straightforward way to avoid the symptoms. Consider nonalcoholic substitutions instead.
  • Tobacco use or exposure to secondhand smoke: Smoking may increase levels of acetaldehyde, which may raise cancer risk.
  • Alcohol use when taking certain medications: Some drugs may make your symptoms more severe.
  • Antacid or antihistamine use to reduce symptoms: These medications mask the symptoms of alcohol intolerance. You may end up drinking even more alcohol, since you don’t feel the adverse effects. If you do so, the problem will worsen.

Alcohol abuse can still develop if someone has alcohol intolerance. Some individuals continue to drink through adverse reactions to feel the pleasurable effects of alcohol.

Heavy drinking and alcohol intolerance may increase the risks of developing specific alcohol-related problems, such as:

  • High blood pressure
  • Cancer of the mouth and throat
  • Esophageal and gastric cancer
  • Higher rates of liver disease (cirrhosis)
  • Late-onset Alzheimer’s disease
  • Hypertension

If you or a loved one is struggling with alcohol intolerance and alcohol addiction, a specialized treatment program will be recommended. Depending on the severity of the condition, an inpatient program may be the most effective course of treatment.

Patients who attend our alcoholic recovery treatment facilities can benefit from some of the following treatment methodologies:

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Having alcohol intolerance doesn’t preclude you from struggling with alcohol addiction.

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[1] NIH –

[2] NCBI –