What Is Alcohol Intolerance?


Alcohol intolerance is a genetic condition that is often inherited. As a type of metabolic disorder, alcohol intolerance occurs because the enzyme (i.e., proteins that help break down food and drink) that typically regulates alcohol metabolism, termed alcohol dehydrogenase, is affected.1 Consequently, the digestive system is unable to effectively break down the alcohol in one’s systems as it normally should do thereby causing discomfort and an array of symptoms. The hereditary nature of the condition means that it is passed down from family members, and one can be affected even if their parents did not directly have the condition.

Differentiation between alcohol intolerance, alcohol allergy, and low alcohol tolerance:

  • Alcohol intolerance – Genetic metabolic condition of the digestive system where the body cannot process alcohol correctly
  • Alcohol allergy – An immune system response where the immune system overreacts to an ingredient in alcohol (such as chemical, grain or preservative) and ends up attacking the alcohol in one’s system
  • Low alcohol tolerance – Generally a social term used to describe someone who experiences the effects of alcohol and ‘gets drunk’ much quicker than others

Causes of alcohol intolerance

can be caused by the dysfunction of alcohol dehydrogenase, a specific enzyme responsible for the alcohol metabolism (i.e., breakdown of alcohol) in the body.2

When ingesting alcohol (which contains ethanol) the following events take place within the digestive system of the body:

  • When an alcoholic beverage is consumed, the alcohol dehydrogenase (ADH) enzyme operated to break down the alcohol in the digestive system
  • The liver converts the ethanol found in alcohol to acetaldehyde, which damages the body through cell damage
  • An additional enzyme termed aldehyde dehydrogenase 2 (ALDH2) works by converting the harmful acetaldehyde into acetic acid (i.e., vinegar), a non-toxic by-product safe for the body

Here it should be noted that in individuals with alcohol intolerance, a genetic mutation (i.e., change in their biological makeup) results in an inactive or less active aldehyde dehydrogenase 2 (ALDH2) enzyme. As a result, the body is prevented from effectively breaking down the acetaldehyde into acetic acid. Failure to complete this final conversion results in an excess of acetaldehyde in the body and symptoms of alcohol intolerance is related to this build-up of acetaldehyde in one’s blood and tissues.

Individuals may also experience intolerance reactions to other ingredients in alcohol besides ethanol, these include:

  • Sulphites (or other preservatives) – Sulphites are added to alcoholic beverages to limit yeast growth and act as a preservative. Examples of common sulphite compounds include potassium bisulphate and potassium metabisulphite
  • Histamines – Histamines are a naturally occurring body chemical that is also present in certain alcoholic beverages due to fermentation or brewing. A lack of diamine oxidase, an enzyme responsible for breaking down histamine, in the body results in allergic reactions
  • Chemicals (grains or other ingredients) – Gluten derived from grains, notably wheat, rye and barley, which can be found in certain alcoholic beverages can result in allergic reactions

Signs and symptoms of alcohol intolerance

The most predominant symptoms of alcohol intolerance are feeling warm, especially in the chest, and an alcohol-flushing reaction, whereby one’s face becomes flushed (i.e., red). In addition to this other signs andsymptoms of alcohol intolerance include:

Symptoms and tolerance levels commonly vary from person to person, however, the main major symptoms to look out for are flushed skin and feeling sick when consuming alcohol.

Management and treatment for alcohol intolerance

The most optimal way to live with alcohol intolerance is to avoid alcohol as much as possible which should theoretically enable you to live without any undesirable consequences from alcohol.

Alternatives, such as non-alcoholic beverages, may be used as substitutes, however, it has been questioned how realistic or attainable it is to completely abstain from drinking alcohol. In turn, when making such a lifestyle change it is vital to establish a support system and recognise the importance of restricting alcohol intake on their individual health.

In instances where one may drink alcohol and experience mild tolerance symptoms, taking prescribed or over-the-counter antihistamines can help reduce certain symptoms such as a study nose or a flushed face. Nevertheless, antihistamines provide temporary relief and are by no means a treatment method one should continuously adopt in favour of continuing to drink alcohol.


Can I continue to drink if I have alcohol intolerance?

Individuals with alcohol intolerance may decide to continue drinking which results in dangerously high levels of enzymes, notably acetaldehyde, accumulating which the body is unable to break down effectively. Consequently, they will continue to experience uncomfortable and distressing symptoms. Additionally, continued exposure to alcohol may put them at a higher risk for other diseases, such as

How common is alcohol intolerance?

Alcohol intolerance is fairly common. Often mistaken as an allergy to alcohol, individuals are actually reacting to other components within their alcoholic drinks. To determine the exact prevalence of alcohol intolerance ongoing research is still being conducted.

Who are at risk of alcohol intolerance?

Alcohol intolerance is genetic therefore the mutated gene can be passed down through the family even if your parents or grandparents do not directly have alcohol intolerance.

Additional risk factors that increase the likelihood of developing alcohol intolerance include:

How is alcohol intolerance diagnosed?

Given the genetic nature of alcohol intolerance, it can be difficult to diagnose. Whilst self-diagnosis of alcohol intolerance is not advised, seeking the assistance of a healthcare professional to receive a diagnosis is strongly advised. When attempting to make a diagnosis in addition to examining one’s medical history and conducting a physical examination, the following test may also be conducted:

  • Ethanol patch test – A cotton pad infused with alcohol is taped to one’s arm and left for several minutes. When the pad is removed the skin is checked for signs of alcohol intolerance such as swelling, hives or redness
  • Skin prick test – A drop of alcohol is applied to the surface of the skin where it is then pricked to see if the alcohol causes a reaction. If one is allergic, then a raised bump or other skin reaction will appear
  • Blood test – Measures the immune’s systems response to alcohol by examining the number of allergy-type antibodies in the bloodstream, commonly termed immunoglobulin E antibodies

The aforementioned tests help medical professionals to rule out any other conditions that may be causing the reaction to alcohol to ensure that you receive the correct diagnosis. To get an accurate diagnosis it may be worthwhile visiting a doctor specialising in alcohol-related conditions.

How can I prevent alcohol intolerance?

Whilst alcohol intolerance is genetically inherited and there remains no cure or treatment method to prevent it, the following behaviours can be integrated into one’s lifestyle to help cope with the condition.

  • Restricting or stopping alcohol consumption
  • Avoiding alcohol when taking medication as this can worsen symptoms
  • Quick smoking directly and avoid second-hand exposure to smoke
  • Read beverage labels to examine whether they contain ingredients or additives, such as sulphates or grains, which are known to cause reactions

When should I see a doctor?

Experiencing a mild alcohol intolerance or intolerance to something else in alcoholic drinks may not necessarily warrant a trip to the doctor. In turn, avoiding alcohol, limiting alcohol consumption, and avoiding certain types of alcoholic beverages may be beneficial. However, serious reactions or severe pains as a result of consuming alcohol should warrant a visit to a doctor to examine the best way to move forward.


Alcohol intolerance refers to a genetic metabolic disorder whereby the digestive system fails to effectively break down alcohol consumed which results in distressing and uncomfortable symptoms. The condition is often inherited from the family however there are additional risk factors that pose a risk to certain groups. Whilst symptoms are indeed undesirable there remains no clinical treatment course therefore affected individuals often limit or abstain from alcohol to reduce the impact that it has on their life. Individuals should consult a medical professional if they are significantly affected by alcohol or require any assistance with their condition. Nevertheless, it is perfectly possible for individuals with an alcohol intolerance to lead an enjoyable and healthy lifestyle.


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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Jaskirat Kanwal

Masters of Science – MSc, Applied Neuropsychology. University of Bristol, UK

Jaskirat currently works in pharmaceutical care and in the mental health sector. Given their extensive background in psychology, they’re currently seeking to undertake their DClinPsych. They hope to study further, and continue in academia and research, with hopes to ultimately become an HCPC registered clinical neuropsychologist.

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