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Facial Redness: Why do some people turn red after drinking alcohol?

Redness is often associated with excessive alcohol consumption. While it is false and stigmatizing to assume that all individuals suffering from erythema consume alcohol, it is true that alcohol tends to cause skin redness in some individuals. What are the causes of this redness? Why does it only affect a portion of the population? Here are some elements of response.

Summary
Published April 9, 2024, updated on April 10, 2024, by Pauline, Head of Scientific Communication — 5 min read

Why does the skin turn red after consuming alcohol?

The appearance of redness on the face after drinking alcohol is a sign of intolerance to this beverage. This phenomenon is usually accompanied by an acceleration of the heart rate, headaches, nausea, vomiting, dizziness, and a general feeling of physical discomfort. All these symptoms are likely to appear after the consumption of any alcoholic beverage, although they are more common when it has a high alcohol content. It's worth noting that what is commonly referred to as alcohol is actually ethanol, a molecule with the brute formula C2H6O.

After the ingestion of ethanol, the majority of its metabolism occurs in the liver. This process begins with a oxidation reaction controlled by the enzyme alcohol dehydrogenase (ADH), linked to NAD+, a cellular coenzyme. This enzyme allows the formation of acetaldehyde (C2H4O) from ethanol. A toxic product, acetaldehyde attacks cell membranes and alters the functioning of mitochondria. It is not only responsible for the state of intoxication but also for the appearance of redness on the face.

High concentrations of acetaldehyde in the human body trigger the release of histamine by mast cells, part of the immune system. Histamine is a chemical mediator that binds to H1 receptors on the endothelial cells of blood vessels, triggering vasodilation. This increase in capillary diameter in turn intensifies blood flow. These two factors are visually reflected in the appearance of redness on the face.

Redness after drinking alcohol: why does it only affect a portion of individuals?

Not everyone is equal when it comes to the redness that accompanies alcohol consumption. Indeed, some people are prone to developing erythema after a drink, while others never blush. A recent study conducted with a large panel of 1475 men showed that only 527 of them, or 36%, exhibited redness after consuming alcohol. This study also revealed that the onset of facial redness was correlated with a higher risk of high blood pressure. Indeed, it seems that this risk increases after 4 drinks of alcohol per week for those prone to redness, while it increases after 8 drinks per week for those not affected by this issue.

Important : Even if you do not experience redness after consuming alcohol, the WHO recommends limiting yourself to two drinks per day and spacing out the days with alcohol. High blood pressure is just one of the risks associated with this beverage: cirrhosis, cognitive disorders, cancers...

Several scientists have investigated the reasons that explain why some people flush and others do not after consuming alcohol. It has been observed that ethnicity plays a certain role in this difference, with individuals with darker skin often being less prone to flushing than those of so-called Caucasian or Asian types. Furthermore, genetics appear to be involved.

Indeed, after the transformation of ethanol into acetaldehyde, the metabolism of alcohol usually continues with the conversion of acetaldehyde into acetic acid (C2H4O2) under the action of the enzyme acetaldehyde dehydrogenase (ALDH2). However, individuals prone to redness tend to have a mutation in the gene coding for ALDH2. More specifically, it would be a substitution of glutamine by a lysine residue at the active site, which results in the inactivation of the ALDH2 enzyme. The metabolism of ethanol is then impacted and an accumulation of acetaldehyde in the body occurs. As mentioned above, this molecule is the cause of redness. The mutation of the ALDH2 enzyme gene is currently the leading hypothesis to explain why some people blush after drinking alcohol.

Sources

  • HISHIDA S. & others. The correlation between facial redness and blood acetaldehyde levels following alcohol consumption. Pharmacology Biochemistry and Behavior (1973).

  • Thesis by Véronique LAFOREST BÉRARD. Alcohol Dependence: Toxic Metabolites of Ethanol and Neurotransmitters (1995).

  • KOHNO S. & al. Acetaldehyde prompts histamine release from human airway mast cells, leading to bronchoconstriction. International Archives of Allergy and Immunology (2004).

  • YOON S. J. & et al. Correlations Between Alcohol Intake, Facial Redness Reaction, and Metabolic Syndrome in Healthy Males. Annals of Epidemiology (2012).

  • YOON S. J. & others. Hypertension Associated with Alcohol Consumption Based on the Facial Flushing Reaction to Drinking. Alcohol: Clinical & Experimental Research (2013).

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