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Alcohol Intolerance: Definition, Causes, Symptoms, Test, and Remedy

Alcohol intolerance refers to the body’s inability to effectively metabolize alcohol and is a condition that affects a significant portion of the population. According to a study by the American Journal of Clinical Nutrition, approximately 7-10% of the global population experience some form of alcohol intolerance. This condition is characterized by an immediate, uncomfortable reaction to alcohol consumption, which ranges from mild to severe.

The primary cause of alcohol intolerance is genetic. Individuals with this condition lack sufficient levels of the enzyme aldehyde dehydrogenase 2 (ALDH2), which is necessary for breaking down ethanol in alcohol. Without enough ALDH2, toxic byproducts like acetaldehyde accumulate in the body, leading to various adverse reactions. Environmental factors and other health conditions, such as asthma or allergies, will exacerbate the symptoms of alcohol intolerance.

Symptoms of alcohol intolerance appear within minutes of alcohol consumption. Common signs include facial flushing, nausea, rapid heartbeat, headache, and nasal congestion. These symptoms are often mistaken for a simple allergic reaction; however, they are indicative of the body’s inability to metabolize alcohol effectively. In some cases, more severe reactions will occur, such as worsening of asthma or even anaphylaxis, especially when combined with specific allergens found in certain alcoholic beverages.

Diagnosing alcohol intolerance is straightforward. A medical professional will recommend a simple test involving alcohol consumption under controlled conditions to observe symptoms. However, the most effective remedy is abstinence from alcohol. For those who do not wish to abstain, limiting intake and choosing alcoholic beverages that are lower in congeners and chemicals that might trigger reactions could help manage the condition. Additionally, over-the-counter antihistamines might alleviate mild symptoms but should be used cautiously and under medical advice.

What is Alcohol Intolerance?

what is alcohol intolerance

Alcohol intolerance is a genetic metabolic disorder, which means it’s passed down from your parents. Even if neither parent exhibits symptoms, they can still transmit a mutated gene that leads to this condition. This specific disorder arises from an issue with the enzyme responsible for metabolizing alcohol (ALDH2). When people with alcohol intolerance consume even small amounts of alcohol (ethanol), they experience adverse reactions. These reactions begin with a reddening or pinkness of the face (known as alcohol flush) and a sensation of warmth, indicating the body’s struggle to break down alcohol effectively.

According to a Cedars-Sinai article “Alcohol Intolerance: What You Need to Know” by Nikolas Charles, between 30%-50% of people of East Asian descent have alcohol intolerance, a fact which leads many to refer to the condition as “Asian flush” or “Asian glow.” But although people of Asian ancestry are most at risk for alcohol intolerance, the condition can affect people of all races and ethnicities. According to the World Health Organization,​​ countries with high prevalence of alcohol intolerance, such as Japan and South Korea, public health policies regarding alcohol consumption are specifically tailored to address and educate about alcohol intolerance. These policies include public awareness campaigns and labeling requirements on alcoholic beverages 

What Causes Alcohol Intolerance?

causes of alcohol intolerance

Alcohol intolerance has various causes, and it often stems from a combination of genetic and environmental factors. Here are 5 of the causes of alcohol intolerance:

1. Enzyme Deficiencies

One of the primary causes of alcohol intolerance is the deficiency or reduced activity of the enzyme aldehyde dehydrogenase (ALDH). ALDH is responsible for breaking down acetaldehyde, a toxic byproduct of alcohol metabolism. When ALDH is deficient, acetaldehyde builds up in the body, leading to the symptoms associated with alcohol intolerance.

2. Genetic Factors

Alcohol intolerance is largely determined by genetics, affecting how the body processes alcohol. According to a study from the Mayo Clinic, certain ethnic groups, particularly East Asians, exhibit a notably higher incidence of aldehyde dehydrogenase 2 (ALDH2) deficiency. This deficiency is found in up to 40% of individuals in these populations, making them significantly more prone to experiencing symptoms of alcohol intolerance. The condition is inherited, meaning that it can be passed down from parents to children through mutated genes related to this enzyme, regardless of whether the parents themselves exhibit symptoms.

3. Histamine Intolerance

Some individuals may experience alcohol intolerance due to an underlying histamine intolerance. A study published in The Journal of Allergy and Clinical Immunology states that alcohol intolerance is exacerbated by high levels of histamine in alcoholic beverages such as wine and beer. Some individuals with alcohol intolerance may actually be reacting to histamine or other substances in the alcohol rather than alcohol itself.

4. Sensitivity to Other Components

Alcohol intolerance can also be caused by sensitivity to other substances present in alcoholic beverages, such as sulfites, additives, or preservatives. These substances can trigger allergic-like reactions or worsen symptoms in individuals who are sensitive to them.

5. Medications or Medical Conditions

Certain medications, such as those used to treat infections or disulfiram (a medication for alcohol dependence), will cause adverse reactions when combined with alcohol. Additionally, certain medical conditions, such as liver disease or gastrointestinal disorders, will make individuals more susceptible to alcohol intolerance. According to a study published in Journal of Epidemiology and Community Health, individuals with alcohol intolerance, especially those with an ALDH2 deficiency, have a significantly increased risk of developing esophageal cancer if they consume alcohol. The risk is elevated due to the accumulation of acetaldehyde, a known carcinogen.

What are the Signs of Alcohol Intolerance?

Alcohol intolerance manifests through various signs and symptoms, which typically occur shortly after consuming alcohol. Here are some common signs of alcohol intolerance:

  • Facial flushing: One of the most noticeable signs is facial flushing, which is characterized by redness and warmth in the face, neck, and sometimes the upper body. This occurs due to the accumulation of acetaldehyde, a byproduct of alcohol metabolism.
  • Rapid heartbeat: Alcohol intolerance causes an increased heart rate, known as tachycardia. This will lead to a sensation of palpitations or a racing heart.
  • Nausea and vomiting: Individuals with alcohol intolerance experience gastrointestinal symptoms such as nausea, vomiting, or stomach discomfort. These symptoms occur shortly after alcohol consumption.
  • Headaches: Alcohol intolerance triggers headaches or migraines in some individuals. The exact mechanism behind alcohol-induced headaches is not fully understood, but it may involve the release of certain substances that cause blood vessels in the brain to dilate.
  • Low blood pressure: Some people with alcohol intolerance experience a drop in blood pressure after consuming alcohol. This leads to lightheadedness, dizziness, or even fainting.
  • Nasal congestion and runny nose: Alcohol intolerance causes nasal congestion, sneezing, and a runny nose, similar to allergic reactions. This is associated with histamine release triggered by alcohol.
  • Skin reactions: In some cases, alcohol intolerance causes skin reactions such as hives, itching, or redness.

Here are some of the additional symptoms of alcohol intolerance:

  • Redness or itching of the eyes
  • Swelling of the face, lips, or tongue
  • Difficulty breathing
  • Fatigue or weakness
  • Mental confusion or foggy thinking

How to get Diagnosed or Tested for Alcohol Intolerance?

Diagnosing alcohol intolerance primarily involves a consultation with your healthcare provider, who will inquire about any adverse reactions you experience following alcohol consumption. This discussion is crucial for determining whether your symptoms align with those of alcohol intolerance.

Additionally, a specific test known as the ethanol patch test may be conducted. In this test, your healthcare provider will:

  1. Apply a drop of ethanol onto a gauze pad.
  2. Secure the gauze pad to your arm using medical tape.
  3. Allow the patch to remain in place for approximately seven minutes.
  4. Remove the gauze and examine the area for any signs of redness, itching, or swelling.

This test helps confirm a diagnosis by observing the skin’s reaction to direct contact with ethanol.

How Do You Prevent Alcohol Intolerance?

If you’re alcohol intolerant, there’s no sure-fire way to consume alcohol without getting the reactions. However, below are some tips you can implement: 

  • Avoid or limit alcohol consumption.
  • Choose beverages with lower alcohol content.
  • Stay hydrated by drinking plenty of water.
  • Be aware of your body’s reactions to alcohol and listen to any warning signs.
  • Avoid mixing alcohol with medications or substances that interact negatively.
  • Identify and avoid triggers that worsen your symptoms, such as specific types of alcohol or additives. Always read the labels.
  • Consider alternative non-alcoholic beverages when socializing or celebrating.
  • Seek medical advice and guidance if you suspect alcohol intolerance or experience severe symptoms.

What is the Difference Between Alcohol Intolerance and Alcohol Allergy?

alcohol intolerance vs alcohol allergy

Alcohol intolerance and alcohol allergy are two distinct conditions with different underlying mechanisms and symptoms. Here are the key differences between the two:

Alcohol Intolerance

  • Cause: Alcohol intolerance is primarily caused by the body’s inability to metabolize or process alcohol efficiently. It is often related to a deficiency in the enzyme aldehyde dehydrogenase (ALDH) or an inability to break down acetaldehyde, a byproduct of alcohol metabolism.
  • Symptoms: Common symptoms of alcohol intolerance include facial flushing, rapid heartbeat, nausea, vomiting, headaches, low blood pressure, nasal congestion, and skin reactions. These symptoms are typically not life-threatening but can be uncomfortable or unpleasant.
  • Mechanism: Alcohol intolerance is primarily a reaction to the direct effects of alcohol or its metabolites, such as acetaldehyde, on the body. It is not an immune response like an allergy.

Alcohol Allergy

  • Cause: Alcohol allergy is an immune system response to specific components in alcoholic beverages, such as proteins or other substances. It is caused by an overreaction of the immune system to these allergens.
  • Symptoms: Allergic reactions to alcohol can manifest as skin rashes, hives, itching, swelling (angioedema), difficulty breathing, wheezing, nasal congestion, runny nose, gastrointestinal symptoms, and in severe cases, anaphylaxis. These symptoms can be life-threatening and require immediate medical attention.
  • Mechanism: Alcohol allergies involve an immune system response, specifically an IgE-mediated allergic reaction. The immune system perceives certain components in alcohol as harmful and triggers an allergic response, releasing histamine and other chemicals.

Note that alcohol intolerance and alcohol allergy can coexist in some individuals. If you suspect you have either or both conditions, it is recommended to seek medical evaluation and diagnosis from a healthcare professional.

Can Alcohol Intolerance Develop Over Time?

Yes, someone can develop alcohol intolerance later in life, although it is relatively uncommon. Some potential factors include changes in liver function, hormonal changes, the onset of certain medical conditions, or the use of medications that interact with alcohol. Additionally, lifestyle changes, such as decreased alcohol consumption or periods of abstinence, sometimes leads to increased sensitivity to alcohol when it is reintroduced.

How is alcohol intolerance different from caffeine intolerance?

Alcohol intolerance and caffeine intolerance are both metabolic disorders, but they involve different substances and symptoms. Alcohol intolerance occurs when the body lacks the enzymes needed to break down alcohol, leading to symptoms like facial flushing, nausea, and rapid heartbeat. Caffeine intolerance involves an exaggerated response to caffeine, resulting in symptoms such as jitteriness, headaches, and insomnia. Both conditions can significantly impact an individual’s quality of life, but the substances involved and the mechanisms behind the intolerance differ.

Can alcohol intolerance lead to alcohol addiction?

Alcohol intolerance and alcohol addiction are separate conditions, and having alcohol intolerance typically discourages alcohol consumption due to the immediate and uncomfortable symptoms it causes. Individuals with alcohol intolerance are less likely to develop alcohol addiction because their adverse reactions make drinking unpleasant. However, it is important to note that a person with alcohol intolerance can still develop addiction to other substances, and it is crucial to be aware of the risks associated with substance abuse in general.

What lifestyle changes can help manage alcohol intolerance?

Managing alcohol intolerance involves making specific lifestyle changes to avoid triggering symptoms. These changes include avoiding alcoholic beverages and foods that contain alcohol, reading labels carefully to identify hidden sources of alcohol, and opting for non-alcoholic alternatives during social events. Additionally, maintaining a healthy diet and staying hydrated can support overall well-being and reduce the impact of accidental alcohol exposure. For those who frequently attend events where alcohol is present, having a plan in place to manage social situations without consuming alcohol is essential.

Can alcohol intolerance be confused with a hangover?

Alcohol intolerance and a hangover are different. Alcohol intolerance is a reaction to alcohol itself, with symptoms occurring shortly after consumption. Hangovers result from excessive alcohol consumption and are typically felt the day after consumption.

How is alcohol intolerance diagnosed?

Alcohol intolerance is diagnosed based on a person’s symptoms and medical history. A healthcare professional will conduct an evaluation and ask questions about the individual’s alcohol consumption patterns and any associated symptoms experienced.

In some cases, a healthcare professional will recommend an alcohol challenge test. This involves the supervised consumption of a controlled amount of alcohol to observe the individual’s reaction. During the test, vital signs, symptoms, and any physical changes are closely monitored.

Ryan Wakim MD
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Dr. Wakim is a board-certified psychiatrist with a passion for and expertise in addiction, mood disorders, trauma-related disorders and the subspecialty of interventional psychiatry. He obtained his medical degree from West Virginia University where he also completed his residency training, finishing as chief resident. Dr. Wakim co-founded and served as the CEO of Transformations leading to a successful merger with Shore Capital in May 2021. He is purpose driven towards improving the standard of and removing stigma related to behavioral healthcare. Dr. Wakim enjoys golf, traveling and time spent with his two dogs, Lulu and Rayna.

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