When a person’s cheeks turn red after consuming alcohol, this common physiological response is known as “alcohol flush” or “Asian glow.” This reaction indicates the body processes alcohol in a distinct way. It is a specific metabolic response, not an allergy. Understanding this reaction involves looking into how the body breaks down alcohol.
The Role of Alcohol Metabolism
The body primarily metabolizes alcohol (ethanol) in a two-step process, mainly in the liver. First, an enzyme called alcohol dehydrogenase (ADH) converts ethanol into acetaldehyde, a highly reactive and toxic compound. This initial step changes alcohol into a substance that can cause cellular damage if it accumulates. Acetaldehyde is the key molecule responsible for the visible redness and other uncomfortable symptoms experienced during flushing.
Next, another enzyme, aldehyde dehydrogenase 2 (ALDH2), rapidly breaks down the toxic acetaldehyde into a harmless substance called acetate. Acetate is then further broken down into carbon dioxide and water, which the body easily eliminates.
Genetic Factors
The reason some individuals experience alcohol flush while others do not lies in their genetic makeup. A specific genetic variation in the ALDH2 enzyme, the ALDH22 allele, causes this reaction. Individuals with this genetic variant have an ALDH2 enzyme that is either less efficient or largely inactive.
When the ALDH2 enzyme is impaired, acetaldehyde cannot be converted into acetate quickly enough, leading to its accumulation in the bloodstream. This buildup triggers the body’s response, including the characteristic facial flushing as blood vessels dilate. The ALDH22 allele is particularly common in people of East Asian descent, with approximately 30% to 50% of individuals of Chinese, Japanese, and Korean ancestry carrying at least one copy of this variant. While most prevalent in these populations, this genetic predisposition can also occur in other ethnic groups.
Beyond Facial Flushing: Other Symptoms and Health Risks
While facial flushing is the most noticeable sign of this metabolic difference, individuals with an ALDH2 deficiency may experience other immediate symptoms after drinking alcohol. These can include nausea, a rapid heartbeat, headaches, and dizziness. Some people also report a sensation of overheating, general physical discomfort, low blood pressure, or a stuffy nose. These reactions serve as immediate indicators of acetaldehyde buildup in the body.
Beyond these immediate symptoms, continued alcohol consumption in individuals with ALDH2 deficiency is associated with several long-term health risks. Acetaldehyde is classified as a Group 1 carcinogen, meaning it is cancer-causing. The accumulation of this toxic compound can lead to DNA damage, significantly increasing the risk of certain cancers, particularly those of the esophagus, head, and neck. There is also an elevated risk of cardiovascular issues, including hypertension, heart disease, and stroke. Liver disease is another concern for those who continue to drink regularly despite this metabolic difference.
What to Do If You Experience Alcohol Flushing
For individuals who experience alcohol flush, the most effective approach is to limit or avoid alcohol consumption. This is because the flushing reaction is a signal of acetaldehyde accumulation, a compound with known toxic and carcinogenic properties. There is no established cure or treatment that corrects the underlying ALDH2 enzyme deficiency.
While some medications, such as histamine-2 blockers or topical solutions, can help mask the visible symptoms like facial redness, they do not address the continued buildup of acetaldehyde in the body. Relying on these remedies might conceal warning signs without mitigating the internal health risks. Therefore, understanding this physiological response and adjusting drinking habits accordingly is the most responsible course of action for personal well-being.