Commonly nicknamed the “Asian glow” or “Asian flush,” alcohol flush reaction is a physical response to drinking alcohol seen predominantly in people of East Asian descent. This condition is marked by a reddening of the face, increased heart rate, and sometimes nausea or headaches shortly after consuming alcohol.About 560 million people worldwide, which makes it roughly 8% of the global population, carry a genetic mutation called ALDH2*2 that causes this reaction. An estimated 45% of East Asians experience flushing when they drink, and many use antihistamines to mask the symptoms. But researchers warn that these visible reactions are more than just a cosmetic issue, they’re a red flag indicating a heightened vulnerability to serious diseases. We spoke to Dr Gaurav Mehta, Consultant, Gastroenterology/Hepatology and Transplant Hepatology, Kokilaben Dhirubhai Ambani Hospital, Mumbai, who explains that the use of antihistamines (such as diphenhydramine or loratadine) to mask alcohol flush is medically discouraged. These medications may suppress visible symptoms like redness and discomfort, but they do not reduce acetaldehyde accumulation or its systemic toxic effects. "By concealing early warning signs, individuals may consume more alcohol than they should, leading to increased toxic load, liver stress, and potential long-term complications. Additionally, combining alcohol with antihistamines can impair cognitive and motor functions, increasing the risk of accidents, sedation, and drug interactions," he says.What Causes It?The root cause of alcohol flush reaction lies in how alcohol is metabolized in the body. Normally, alcohol is broken down in two steps.First, it is converted into acetaldehyde, a compound far more toxic than alcohol itself. Then, acetaldehyde is quickly broken down into acetate by an enzyme called aldehyde dehydrogenase 2 (ALDH2), which the body can safely eliminate.However, in people with the ALDH2*2 mutation, this second step is impaired. Their version of the ALDH2 enzyme has little to no activity, causing acetaldehyde to accumulate in the bloodstream. This toxic buildup is what leads to the flushing and other symptoms.The World Health Organization classifies acetaldehyde as a Group 1 carcinogen, meaning there is strong evidence that it causes cancer in humans. Even with moderate alcohol intake, such as two beers, the acetaldehyde levels in people with this mutation can reach carcinogenic levels.From an oncological standpoint, explains Dr Mehta, this is highly alarming. "Acetaldehyde is both mutagenic and genotoxic it damages DNA, interferes with DNA repair mechanisms, and promotes inflammation, all of which can drive carcinogenesis. The risk of esophageal squamous cell carcinoma is significantly higher in ALDH2-deficient individuals who consume alcohol, even in small amounts."The danger is further compounded by the fact that these individuals often develop visible flushing reactions, which are frequently misunderstood or dismissed. In many cases, people attempt to suppress the symptoms using antihistamines or continue drinking socially, unaware that they are exposing their bodies to a carcinogenic environment.Why It’s DangerousWhile many consider alcohol flush reaction an inconvenience, the health risks it signals are far more serious. Experts have linked the ALDH2*2 mutation with significantly elevated risks for several life-threatening conditions if alcohol consumption continues.Dr Mehta explains, "While this reaction may appear harmless or cosmetic, it is a clinical marker of impaired alcohol metabolism. Persistent exposure to elevated acetaldehyde levels is linked to cellular damage, inflammation, and increased risk for certain cancers. Thus, the flush reaction can indicate a deeper metabolic vulnerability rather than a simple sensitivity."People with the mutation who drink moderately (defined as two drinks per day for men and one for women) have a 40 to 80 times higher risk of developing esophageal cancer compared to those without the mutation. The risk increases with the amount of alcohol consumed, making it a dose-dependent danger.The mutation is also associated with higher risks of:Head and neck cancersGastric (stomach) cancerCoronary artery diseaseStrokeOsteoporosisImportantly, these elevated health risks are not seen in non-drinkers with the same mutation, highlighting that alcohol intake is the trigger.Why Antihistamines Don’t HelpMany young people, particularly college students, take over-the-counter antihistamines like Pepcid AC or Zantac to reduce the visible symptoms of alcohol flush reaction. While these drugs may lessen skin flushing by reducing blood vessel dilation, they do nothing to prevent the dangerous accumulation of acetaldehyde in the bloodstream.Experts caution that using antihistamines this way is risky. By masking the body’s warning signals, individuals may end up drinking more than they should, unknowingly increasing their health risks.A Problem of AwarenessDespite the potentially deadly consequences, awareness of the ALDH2*2 mutation remains low. The variant is believed to have originated from a single individual in Southeast China 2,000 to 3,000 years ago. Today, its prevalence is highest in Taiwan (49 percent), Japan (40 percent), China (35 percent), and South Korea (30 percent). Yet, alcohol consumption in East Asia continues to rise.Between 1990 and 2017, alcohol use in East Asia increased from 48.4 percent to 66.9 percent. The region now bears the highest burden of alcohol-attributable cancers globally, with 5.7 percent of all cancer cases linked to alcohol, nearly double the rate in North America.Many people still believe that facial flushing from alcohol is harmless or even a sign of a strong liver. In fact, it’s a clear signal of toxicity and should not be ignored.Raising Public Education and Health LiteracyEfforts to raise awareness are growing. In Taiwan, researchers and health advocates founded the Taiwan Alcohol Intolerance Education Society, which collaborates with government agencies to educate the public. The group launched National Taiwan No Alcohol Day on May 9, with “5-9” sounding like “no alcohol” in Mandarin, a clever linguistic nudge toward abstinence, as reported by the Washington Post.Research also suggests that personalized health information can help. A study conducted among Asian American young adults found that those who were informed about their genetic risks related to the ALDH2*2 variant reduced both their drinking frequency and volume over the following month.Experts emphasize that the message is clear: if you experience alcohol flush reaction, your body is sounding an alarm. Ignoring it may come at a serious cost.