Alcohol Intolerance: Symptoms and Causes

Alcohol intolerance involves a variety of physical responses due to the body’s inability to fully metabolize alcohol. Even small amounts trigger symptoms in people with this intolerance, as their bodies cannot break down alcohol into harmless byproducts. These responses tend to be rapid and range from uncomfortable symptoms to severe, life-threatening reactions.

The common Alcohol Intolerance Symptoms include flushing, headaches, nausea, and vomiting, which appear shortly after consuming minimal alcohol. Studies indicate that some individuals experience these effects after as little as 1 ml of pure alcohol, triggering hives or urticarial reactions in specific cases.

For a smaller percentage, reactions resemble severe allergic reactions like anaphylaxis. While alcohol-induced anaphylaxis is rare, cases have been documented where individuals encountered health effects immediately following alcohol exposure, as reported by Sticherling and Brasch in Alcohol: intolerance syndromes, urticarial and anaphylactoid reactions (1999).

The main causes of Alcohol Intolerance involve genetic factors, particularly deficiencies in Aldehyde Dehydrogenase (ALDH2), an enzyme important for breaking down alcohol. ALDH2 deficiency leads to acetaldehyde buildup, a compound known for triggering allergy-like symptoms in those with this genetic trait. For instance, individuals with this deficiency experience a blood acetaldehyde increase of up to 10 times more than those without it.

Furthermore, heightened sensitivity to histamines, which are released upon alcohol drinking, intensifies allergy symptoms for some people. These factors explain why certain populations, including about 36% of East Asian individuals, are more likely to experience alcohol intolerance.

While no permanent treatment exists for Alcohol Intolerance, avoiding alcohol is the most effective prevention method. Consulting with a healthcare provider aids in identifying specific triggers and establishing personalized management strategies to mitigate symptoms effectively.

What Is Alcohol Intolerance?

Alcohol Intolerance is a condition where the body cannot properly process alcohol, resulting in uncomfortable and sometimes severe physical reactions even after minimal intake. This reaction stems from a genetic deficiency in Aldehyde Dehydrogenase (ALDH2), an enzyme important for breaking down acetaldehyde, a toxic byproduct of alcohol. When ALDH2 is insufficient, acetaldehyde builds up in the bloodstream, causing symptoms such as flushing, headaches, nausea, vomiting, and, in some cases, hives or anaphylaxis.

The mechanism behind alcohol intolerance is metabolic rather than immune-based, which differentiates it from an Alcohol Allergy. Alcohol intolerance does not involve immunoglobulin E (IgE) antibodies, which are active in allergic reactions, meaning that it is not a true allergic response. This condition is also distinct from intoxication, as it does not stem from consuming large amounts of alcohol but from the body’s inability to metabolize alcohol effectively.

For those with alcohol intolerance, reactions appear after consuming as little as 1 ml of pure alcohol, highlighting the severity and immediacy of symptoms for affected individuals, as noted by M Sticherling and J Brasch in Alcohol: intolerance syndromes, urticarial and anaphylactoid reactions (1999).

While alcohol intolerance is manageable, it is dangerous, particularly if reactions progress to anaphylactoid responses, which, though rare, is life-threatening. The ICD-10 code for Alcohol Intolerance is T51.0, which categorizes it under the toxic effects of alcohol. According to DSM-5 criteria, alcohol intolerance is not classified as a psychiatric disorder; however, severe cases warrant medical attention, especially when symptoms resemble anaphylaxis.

Recent statistics show that alcohol intolerance is more common in certain populations, with up to 36% of individuals of East Asian descent possessing the ALDH2 deficiency, which predisposes them to the condition. This prevalence demonstrates that genetic background significantly impacts one’s likelihood of experiencing alcohol intolerance.

What Are the Symptoms of Alcohol Intolerance?

The common Alcohol Intolerance Symptoms include various physical, behavioral, and psychological reactions that emerge soon after consuming even small amounts of alcohol. Unlike symptoms from an Alcohol Allergy, these reactions stem from a deficiency in Aldehyde Dehydrogenase (ALDH2), which causes difficulty in breaking down alcohol’s toxic byproducts.

In a study involving 12 patients with adverse reactions to ethanol, 54.5% tested positive for hypersensitivity after consuming 30 mL of ethanol, confirming that symptoms are dose-dependent and influenced by ethanol itself, according to Ehlers, Hipler, Zuberbier, and Worm in Ethanol as a cause of hypersensitivity reactions to alcoholic beverages in 2002. The main physical, behavioral, and psychological symptoms of Alcohol Intolerance are explained below:

Physical Symptoms of Alcohol Intolerance

Physical symptoms of alcohol intolerance are the most noticeable and range from mild discomfort to severe reactions. These symptoms appear within minutes of alcohol drinking, reflecting the body’s rapid response to acetaldehyde buildup.

• Facial flushing: A sudden, red flush on the face and neck is one of the most common physical signs. This occurs as blood vessels dilate in response to rising acetaldehyde levels in the bloodstream.
• Headaches and migraines: Many individuals experience headaches shortly after drinking, with migraines affecting some. The intensity varies depending on individual sensitivity and alcohol intake.
• Nausea and vomiting: A common reaction due to acetaldehyde buildup, which irritates the stomach lining and triggers nausea.
• Skin reactions: Red, itchy patches resembling allergy symptoms like hives appear, especially on the face and arms. While they mimic allergic hives, they result from metabolic stress rather than an immune reaction.
• Anaphylaxis: In rare cases, alcohol intolerance leads to anaphylactic responses, with symptoms like difficulty breathing and lowered blood pressure. Though uncommon, this reaction requires immediate medical attention, as it is life-threatening.

Behavioral Symptoms of Alcohol Intolerance

Behavioral responses to alcohol intolerance develop in people with repeated episodes of alcohol intolerance. These responses stem from a desire to avoid discomfort and potential social embarrassment.

• Avoidance of social drinking: Individuals choose to abstain from alcohol-related events or gatherings to prevent unwanted symptoms in public.
• Caution with food and beverages: Those with alcohol intolerance exhibit hesitation or avoid trying unfamiliar foods or drinks that contain alcohol, even in small amounts.
• Reliance on others for support: People with alcohol intolerance might rely on close friends or family for assistance in social settings to avoid accidentally drinking alcohol or to provide help if a reaction occurs.

Psychological Symptoms of Alcohol Intolerance 

Psychological symptoms of alcohol intolerance arise from the constant anticipation of adverse reactions. These mental responses lead to heightened stress and social anxiety.

• Anxiety in social situations: Anticipation of an adverse reaction leads to stress, particularly in social settings where alcohol is commonly served. This increases self-consciousness and reduces the enjoyment of social interactions.
• Hypervigilance: Some individuals become overly aware of their environment, constantly monitoring for alcohol in foods or drinks, which impacts their sense of ease in various settings.
• Fear of severe reactions: For those who have experienced severe symptoms, such as anaphylactic-like reactions, a persistent fear of recurrence arise, leading to reluctance in engaging socially or trying new foods.

What Are the Causes of Alcohol Intolerance?

The common causes of Alcohol Intolerance include various genetic, enzymatic, and environmental factors that hinder the body’s ability to metabolize alcohol. Unlike an Alcohol Allergy, which involves an immune response, alcohol intolerance stems from the body’s difficulty in processing alcohol effectively.

Below are the primary causes of alcohol intolerance:

1. Genetic Causes 

Genetic factors are a primary cause of Alcohol Intolerance, especially among individuals of East Asian descent. In this population, approximately 36% have a genetic mutation affecting Aldehyde Dehydrogenase (ALDH2), an enzyme important for breaking down acetaldehyde, a toxic byproduct of alcohol. Without sufficient ALDH2, acetaldehyde builds up quickly, leading to flushing, headaches, and nausea soon after alcohol drinking.

These genetic mutations make people more susceptible to symptoms even with small amounts of alcohol. Symptoms appear after as little as 1 ml of pure alcohol in people with ALDH2 deficiency, according to M Sticherling and J Brasch in Alcohol: intolerance syndromes, urticarial and anaphylactoid reactions (1999).

2. Ingredients in Alcoholic Beverages

Ingredients added to alcoholic beverages, such as sulfites, histamines, and preservatives, exacerbate or mimic Alcohol Intolerance symptoms. For instance, sulfites, commonly found in wine and beer, trigger reactions in sensitive individuals, causing symptoms like skin rashes, nasal congestion, and even asthma-like symptoms.

Histamines, naturally present in fermented beverages,  induce headaches, nausea, and flushing in those with heightened sensitivity. This sensitivity to certain ingredients complicates the body’s response to alcohol, leading to symptoms that resemble allergic reactions and are sometimes mistaken for alcohol intolerance.

3. Enzyme Deficiencies 

Deficiency in Aldehyde Dehydrogenase (ALDH2) is a major cause of alcohol intolerance, leading to an inability to efficiently process acetaldehyde. When alcohol is consumed, it is metabolized into acetaldehyde, a toxic compound. In individuals with ALDH2 deficiency, this acetaldehyde remains in the bloodstream, causing immediate symptoms like nausea, facial flushing, and dizziness.

Those with this enzyme deficiency experience a rapid buildup of acetaldehyde, causing discomfort after small amounts of alcohol and even severe reactions, depending on the dosage, as detailed by Ehlers, Hipler, Zuberbier, and Worm in Ethanol as a cause of hypersensitivity reactions to alcoholic beverages (2002).

4. Medical Conditions

Certain health conditions heighten sensitivity to alcohol and lead to symptoms associated with Alcohol Intolerance. For example, individuals with asthma or Hodgkin’s lymphoma experience exacerbated reactions, including respiratory distress, due to their bodies’ altered responses to alcohol.

Gastrointestinal conditions, like peptic ulcers and inflammatory bowel disease, also increase the severity of symptoms by making the stomach more sensitive to alcohol’s effects. These conditions produce reactions similar to allergic reactions, complicating the accurate diagnosis of alcohol intolerance.

5. Medications

Medications impact the body’s ability to process alcohol, leading to intolerance symptoms or intensifying them. For instance, certain antibiotics, antidepressants, and pain medications inhibit enzyme activity, particularly Aldehyde Dehydrogenase, which delays the breakdown of alcohol’s toxic byproducts.

This interaction causes individuals to experience heightened symptoms like flushing, nausea, and headaches after drinking small amounts of alcohol.  

What Risk Factors Contribute to Alcohol Intolerance?

Risk factors for Alcohol Intolerance include genetic mutations, enzyme deficiencies, and other physiological and environmental influences that increase sensitivity to alcohol. The following are common risk factors:

• Genetic Predisposition
  Genetic predisposition is a significant risk factor for Alcohol Intolerance, particularly among East Asian populations, where up to 36% of individuals have a mutation that affects Aldehyde Dehydrogenase (ALDH2). This mutation causes an enzyme deficiency, which prevents the effective breakdown of acetaldehyde, a toxic byproduct of alcohol metabolism. As a result, even small amounts of alcohol trigger symptoms like flushing, nausea, and headaches, as demonstrated in findings by M Sticherling and J Brasch, who observed symptoms emerging from as little as 1 ml of alcohol (Alcohol: intolerance syndromes, urticarial and anaphylactoid reactions, 1999).
• Enzyme Deficiency
  Enzyme deficiency, specifically in Aldehyde Dehydrogenase (ALDH2), is another primary risk factor for alcohol intolerance. Individuals with this deficiency experience rapid acetaldehyde buildup in the bloodstream after drinking alcohol, leading to immediate reactions such as skin flushing, nausea, and headaches. Research by Ehlers, Hipler, Zuberbier, and Worm indicated that 54.5% of patients with ALDH2 deficiency showed hypersensitivity symptoms after ingesting only 30 mL of ethanol, highlighting the enzyme’s role in processing alcohol (Ethanol as a cause of hypersensitivity reactions to alcoholic beverages, 2002).
• Underlying Medical Conditions
  Underlying medical conditions such as asthma, Hodgkin’s lymphoma, and gastrointestinal disorders heighten sensitivity to alcohol, making symptoms more pronounced. For example, individuals with asthma experience respiratory difficulties, while those with gastrointestinal conditions like inflammatory bowel disease find alcohol exacerbates symptoms such as abdominal pain and nausea. These conditions influence how the immune and digestive systems respond to alcohol, increasing the likelihood of experiencing intolerance symptoms.
• Medication Interactions
  Medication interactions significantly impact alcohol intolerance, as certain drugs, including antibiotics, antidepressants, and pain relievers, interfere with the body’s alcohol metabolism. These medications reduce ALDH2 activity, slowing down the breakdown of alcohol’s toxic byproducts. As a result, individuals taking these medications experience intensified symptoms like flushing, headaches, and nausea after even minimal alcohol intake.

What Are the Risks of Alcohol Intolerance?

The common risks of Alcohol Intolerance include a range of physical, psychological, and behavioral consequences that emerge from the body’s inability to metabolize alcohol effectively. Physical risks involve immediate reactions like nausea, headaches, and, in severe cases, respiratory distress. Psychological risks include social anxiety and heightened stress over possible adverse reactions in public.

Behavioral risks are reflected in changes to one’s lifestyle, such as avoiding social events or relying on others for support in alcohol-related settings.

The physical, psychological, and behavioral risks of alcohol intolerance are explained below:

Physical Risks of Alcohol Intolerance

Physical risks of Alcohol Intolerance involve immediate bodily reactions that range from mild discomfort to severe symptoms, affecting both short-term and long-term health. Individuals with alcohol intolerance experience nausea and vomiting soon after drinking alcohol due to a buildup of toxic byproducts.

Headaches and migraines frequently accompany these symptoms, along with facial flushing and an increased heart rate as blood vessels dilate. In severe cases, reactions progress to anaphylaxis, a life-threatening condition impacting breathing and blood pressure, which requires emergency intervention.

Repeated alcohol exposure also increases the risk of liver damage, leading to long-term conditions such as cirrhosis. In a study on alcoholic cirrhosis, daily alcohol drinking averaged 190 grams in men, contributing to liver complications in cases of prolonged use, according to Wilkinson, Santamaria, and Rankin in Epidemiology of Alcoholic Cirrhosis.

Psychological Risks of Alcohol Intolerance

Psychological risks of Alcohol Intolerance arise from the stress and anxiety associated with potential reactions, significantly impacting mental well-being and social comfort. Many people with alcohol intolerance experience social anxiety in settings where alcohol might be served, leading to discomfort and a tendency to avoid social gatherings.

This hypervigilance extends to constantly monitoring for potential alcohol exposure, adding stress to daily interactions. The psychological impact is particularly pronounced in individuals with a family history of alcohol-related health issues, as noted by Wilkinson, Santamaria, and Rankin, who found that 46% of patients with alcoholic cirrhosis had relatives with alcohol issues.

This familial connection heightens personal anxieties and stress about reactions, further complicating social interactions and mental peace.

Behavioral Risks of Alcohol Intolerance

Behavioral risks of Alcohol Intolerance involve lifestyle modifications that individuals adopt to avoid adverse reactions, affecting both personal choices and social relationships. People with alcohol intolerance choose to avoid social or professional events where alcohol is commonly served, limiting opportunities for interaction and engagement.

Some adopt restrictive dietary habits to avoid foods or drinks that might contain alcohol, which affects daily routines and meal planning. Additionally, many people with alcohol intolerance rely on close friends or family members for support in settings where alcohol is present, creating a dependency that influences social behavior and reinforces avoidance of situations involving alcohol.

How Is Alcohol Intolerance Diagnosed?

Alcohol Intolerance is diagnosed through a combination of assessments and tests aimed at identifying an individual’s sensitivity to alcohol and pinpointing underlying causes, such as enzyme deficiencies or genetic factors. This condition, marked by immediate reactions like flushing, nausea, and headaches after consuming even small amounts of alcohol, is confused with Alcohol Allergy or other sensitivities.

To accurately diagnose alcohol intolerance, medical professionals look for consistent patterns in symptoms and apply a series of targeted diagnostic methods. These methods include gathering a personal and family health history, conducting physical examinations, performing patch and blood tests, and using elimination testing to confirm alcohol as the trigger. Each diagnostic tool provides insights into the patient’s metabolic response to alcohol and helps rule out other conditions, ensuring a clear and precise diagnosis.

• Medical History Assessment
  A medical history assessment helps determine if a person has experienced symptoms of alcohol intolerance, such as flushing, headaches, or nausea, and whether these reactions occur shortly after alcohol drinking. The purpose is to identify patterns and rule out other conditions, such as an Alcohol Allergy. Components include a detailed review of symptoms, frequency, and family history, which is important as alcohol intolerance has genetic links.
• Physical Examination
  A physical examination helps identify visible signs of alcohol intolerance, such as skin reactions, facial flushing, or respiratory issues. The purpose is to observe any immediate physical signs that are triggered or worsened by alcohol exposure. Components include blood pressure measurement, checking for skin reactions, and observing breathing patterns to detect any physiological responses.
• Ethanol Patch Test
  The ethanol patch test is used to observe skin reactions to ethanol, helping diagnose sensitivity to alcohol. The purpose is to measure local skin responses when a small amount of ethanol is applied to the skin. Components include applying an ethanol-soaked pad to the skin for a set period and monitoring for reactions like redness, itching, or swelling.
• Blood Tests
  Blood tests detect enzyme deficiencies, especially Aldehyde Dehydrogenase (ALDH2) deficiency, which is a common cause of alcohol intolerance. The purpose is to measure enzyme levels or genetic markers linked to alcohol metabolism issues. Components include testing for acetaldehyde levels after alcohol drinking or genetic testing to identify ALDH2 mutations, both of which indicate a high likelihood of alcohol intolerance.
• Elimination Testing
  Elimination testing involves abstaining from alcohol for a period to see if symptoms resolve, followed by reintroduction under controlled conditions. The purpose is to confirm alcohol as the cause of symptoms by eliminating other potential triggers. Components include a period of complete alcohol avoidance, followed by a supervised reintroduction to observe any recurrence of symptoms.

Is There a Cure for Alcohol Intolerance?

No, there is no cure for Alcohol Intolerance. This condition stems primarily from genetic factors, such as a deficiency in the enzyme Aldehyde Dehydrogenase (ALDH2), which prevents the body from fully breaking down alcohol’s toxic byproducts. Due to the genetic nature of ALDH2 deficiency, treatments are limited to managing symptoms and avoiding alcohol rather than reversing the intolerance itself.

Studies show that people with ALDH2 deficiency experience adverse reactions after as little as 1 ml of alcohol, indicating high sensitivity and difficulty in tolerating any alcohol exposure, according to M Sticherling and J Brasch in Alcohol: intolerance syndromes, urticarial and anaphylactoid reactions.

What Is the Remedy for Alcohol Intolerance?

The only definitive remedy for Alcohol Intolerance is complete avoidance of alcohol, as this condition is due to genetic enzyme deficiencies, such as in Aldehyde Dehydrogenase (ALDH2), which prevents the body from properly breaking down alcohol byproducts. For those who choose to drink alcohol despite intolerance, managing symptoms involves strategies that reduce the likelihood of reactions.

According to Vally and Thompson, avoiding wines high in sulfite additives helps, as sulfites are known to trigger asthma-like symptoms in some individuals with alcohol intolerance. Their study on wine-induced asthma used both single and cumulative doses of sulfites and found that approximately 60% of participants with sulfite sensitivity reported respiratory symptoms after cumulative exposure, indicating a dose-dependent effect.

In addition, opting for low-sulfite or sulfite-free wines and, in some cases, using antihistamines under medical supervision alleviate mild reactions. However, Vally and Thompson emphasize that complete avoidance of alcohol remains the most effective approach for managing alcohol intolerance, as discussed in Role of sulfite additives in wine-induced asthma: single dose and cumulative dose studies (2003).

Can You Prevent Alcohol Intolerance?

No, Alcohol Intolerance cannot be prevented, as it is primarily caused by genetic factors, specifically a deficiency in Aldehyde Dehydrogenase (ALDH2), an enzyme responsible for metabolizing alcohol byproducts. This enzyme deficiency is inherited and leads to the accumulation of acetaldehyde, a toxic compound, which causes symptoms like flushing, nausea, and headaches even after minimal alcohol drinking.

Studies show that individuals of East Asian descent are particularly affected, with about 36% carrying a genetic mutation that impairs ALDH2 function. Although alcohol intolerance cannot be prevented, individuals manage symptoms by avoiding alcohol or choosing low-sulfite options to reduce reactions.

According to Vally and Thompson, managing additives such as sulfites, which exacerbate reactions, helps in mild cases, but complete avoidance of alcohol remains the only reliable approach to managing this condition.

What Is the Difference Between Alcohol Intolerance and Alcohol Tolerance? 

The main difference between Alcohol Intolerance and Alcohol Tolerance lies in how the body reacts to alcohol: alcohol intolerance causes immediate adverse reactions even at low doses due to genetic enzyme deficiencies, while alcohol tolerance refers to the body’s adaptation to alcohol, requiring larger amounts to feel its effects.

Alcohol intolerance stems from a deficiency in Aldehyde Dehydrogenase (ALDH2), leading to symptoms like flushing, nausea, and headaches. In contrast, alcohol tolerance develops over repeated alcohol exposure, as the liver adjusts its metabolic processes.

Studies indicate that up to 36% of East Asians are genetically predisposed to alcohol intolerance due to ALDH2 deficiency, whereas alcohol tolerance varies widely across populations depending on drinking habits and frequency of consumption, as discussed by M Sticherling and J Brasch in Alcohol: intolerance syndromes, urticarial and anaphylactoid reactions (1999).

What Is the Difference Between Alcohol Intolerance and Hangover?

The primary difference between Alcohol Intolerance and a Hangover is that alcohol intolerance involves immediate symptoms following alcohol drinking, while a hangover occurs hours later, the morning after drinking. Alcohol intolerance is caused by enzyme deficiencies, particularly ALDH2, that hinder proper metabolism, leading to symptoms like skin flushing, headaches, and nausea shortly after drinking alcohol.

A hangover, on the other hand, results from dehydration, buildup of toxins, and inflammation due to excessive alcohol intake, causing symptoms like headache, fatigue, and sensitivity to light and sound. Unlike alcohol intolerance, which occurs after just a few milliliters of alcohol, a hangover correlates with the quantity consumed. According to M Sticherling and J Brasch, individuals with alcohol intolerance experience symptoms after as little as 1 ml of alcohol (Alcohol: intolerance syndromes, urticarial and anaphylactoid reactions, 1999).

What Is the Difference Between Alcohol Intolerance and Histamine Intolerance?

Alcohol Intolerance and Histamine Intolerance differ in their underlying causes: alcohol intolerance results from a genetic enzyme deficiency in ALDH2, while histamine intolerance occurs when the body cannot break down histamines due to insufficient Diamine Oxidase (DAO) enzyme levels. Alcohol worsens histamine intolerance symptoms, as certain alcoholic beverages, especially wines and beers, contain high levels of histamines, which lead to flushing, headaches, and nasal congestion.

For people with alcohol intolerance, these symptoms appear due to acetaldehyde buildup rather than histamine accumulation. Approximately 54.5% of individuals with alcohol sensitivity experience symptoms following ethanol exposure, highlighting the metabolic nature of alcohol intolerance, according to Ehlers, Hipler, Zuberbier, and Worm in Ethanol as a cause of hypersensitivity reactions to alcoholic beverages (2002).

What Is the Difference Between Alcohol Intolerance and Alcohol Poisoning?

The key distinction between Alcohol Intolerance and Alcohol Poisoning is that alcohol intolerance involves immediate symptoms from low alcohol intake, while alcohol poisoning is a severe, potentially fatal reaction to excessive alcohol drinking. Alcohol intolerance is due to genetic enzyme deficiencies, like ALDH2, that prevent the proper metabolism of alcohol’s byproducts.

Alcohol poisoning, however, occurs when large amounts of alcohol overwhelm the liver’s processing ability, leading to dangerously high blood alcohol levels that depress the central nervous system, impairing breathing and heart rate. Alcohol poisoning results from binge drinking, with a lethal dose for the average adult estimated at around 0.4% BAC (blood alcohol concentration).

In contrast, individuals with alcohol intolerance experience adverse symptoms after as little as 1 ml of alcohol, as noted by M Sticherling and J Brasch (Alcohol: intolerance syndromes, urticarial and anaphylactoid reactions, 1999).

What Is the Difference Between Alcohol Intolerance and Asian Flush? 

The primary difference between Alcohol Intolerance and Asian Flush is that Asian flush is a visible symptom of alcohol intolerance, not a separate condition. Asian flush, or Alcohol Flush Reaction, is characterized by redness in the face, neck, and sometimes the chest after consuming even small amounts of alcohol, and it is a hallmark of alcohol intolerance among individuals with ALDH2 deficiency, especially within East Asian populations.

In people with this genetic trait, ALDH2 deficiency leads to acetaldehyde buildup, which causes flushing as well as nausea, headaches, and rapid heart rate. Studies show that approximately 36% of East Asians experience this flush reaction, which is part of a broader intolerance to alcohol.