Alcohol flush reaction

Alcohol flush reaction is a type of intolerance related to the ability to metabolize alcohol. This reaction manifests itself mainly as facial redness or flushing, among other symptoms, hence it is also known as alcohol flush reaction.

Flush reaction is a metabolic disorder that involves a decrease in the ability to metabolize alcohol. During the flush, the enzyme alcohol dehydrogenase converts alcohol into acetaldehyde, which is a toxic molecule. The resulting acetaldehyde is converted into other non-toxic molecules by another enzyme called aldehyde dehydrogenase (ALDH). In circumstances where acetaldehyde is not efficiently removed from the systemic circulation, its toxic effects are triggered through the release of histamine responsible for causing flushing in the cala reaction.This is responsible for the flushing reaction consisting of reddening and temperature increase of the face, neck and chest after drinking alcohol, as well as other unpleasant symptoms such as urticaria, nausea, palpitations or tachycardia, nasal congestion, low blood pressure, asthmatic crises, or the occurrence of migraine episodes.

This is more frequent in individuals from Asian populations because variants that trigger a loss of function in the enzyme responsible for transforming acetaldehyde are more frequent in this population.This is why it is also known as "Asian flush" or "Asian glow"; however, it can occur in individuals of any race or ethnicity.

In addition, regular intake of alcohol with this intolerance has been associated with an increased risk of other diseases such as cancer of the mouth and throat, since the acetaldehyde molecule itself is carcinogenic, liver disease or cirrhosis, or even late-onset Alzheimer's disease.

Various studies have shown that this is a heritable trait, having identified its development due to alterations in the ALDH2 gene, a gene that codes for the production of the enzyme aldehyde dehydrogenase 2, which carries out the alcohol metabolization process. The fact that this alcohol intolerance develops means that mutations in the ALDH2 gene have also been indirectly related to a lower frequency of alcohol consumption and dependence.

Number of observed variants

13.5 million variants

Number of variants analyzed in the study

1 variant


National Institute on Alcohol Abuse and Alcoholism. Alcohol Flush Reaction [May 2022]

Cleveland Clinic. Alcohol Intolerance. [May 2022]

Chen CC et al. Interaction between the functional polymorphisms of the alcohol-metabolism genes in protection against alcoholism. Am J Hum Genet. 1999 Sep;65(3):795-807.

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