The holiday season is when the "Asian glow" shows up in photos: a face that turns red after one glass, sometimes with a racing heart, a headache or nausea. Online, it is often treated as a cosmetic problem with a trick to fix it: take an antacid before drinking and the redness fades. That advice misses the point. The flush is not the problem. It is a signal that a cancer-causing compound is building up in your body, and hiding the signal does not make the compound go away.
What the flush is telling you
Your body breaks alcohol down in two steps. First, enzymes coded by genes such as ADH1B turn ethanol into acetaldehyde. Then the enzyme ALDH2 turns acetaldehyde into harmless acetate. Acetaldehyde is the troublemaker: it widens blood vessels, which causes the redness, and it damages DNA. The International Agency for Research on Cancer classifies acetaldehyde from alcoholic drinks as a Group 1 carcinogen, its highest category (Secretan et al., Lancet Oncology, 2009).
About 540 million people, close to 8% of humanity and roughly a third or more of people of Chinese, Japanese and Korean ancestry, carry a variant of ALDH2 called ALDH2*2 (rs671). With one copy, the enzyme works at a small fraction of its normal capacity. With two copies, it barely works at all, and most people with two copies cannot drink more than a few sips comfortably.
A second gene can add to the effect. A common version of ADH1B, rs1229984, turns ethanol into acetaldehyde faster. It makes the flush more intense and is strongly linked to a lower risk of alcohol dependence (Li et al., Biological Psychiatry, 2011).
The risk is highest in people who flush and keep drinking
The most at-risk group is not people with two copies, who usually avoid alcohol because it makes them feel so unwell. It is people with one copy, who feel bad at first but can get used to drinking. In Japanese studies, drinkers with one ALDH2*2 copy had roughly 6 to 10 times the risk of esophageal cancer of drinkers with a fully working enzyme (Brooks et al., PLoS Medicine, 2009; Yokoyama et al., Cancer Epidemiology, Biomarkers and Prevention, 1998). In people who do not drink, the variant does not raise the risk.
That is why the authors of the 2009 paper proposed something simple: doctors could ask patients whether their face turns red after drinking, a question that identifies most people who carry the variant.
Do antacids and "glow pills" work?
H2 antihistamines such as famotidine are widely shared online as a way to prevent the flush, and many products sold as "Asian glow" remedies follow the same idea. There is no good clinical evidence that they prevent it reliably, and nothing suggests that they lower acetaldehyde, since they do not touch the ALDH2 enzyme. Even when the face stays pale, the acetaldehyde is still there, and so is the damage it does. Removing the warning while keeping the drinking is the worst of both worlds.
The same goes for building tolerance. Drinking more often can make the flush and the nausea feel milder, but your ALDH2 enzyme does not change. People who drink through the flush were precisely the group the 2009 paper worried about.
Many people still do not know alcohol causes cancer
In January 2025, the US Surgeon General issued an advisory on alcohol and cancer. It linked drinking to at least seven types of cancer, about 100,000 cancer cases and 20,000 cancer deaths a year in the United States, and called for warning labels. A national survey a few weeks later found that 56% of US adults knew that regular drinking raises cancer risk, up from 40% a few months earlier (Annenberg Public Policy Center, 2025). That still leaves almost half who do not. For millions of people, the flush is a personal, visible reminder.
What to do if you flush
- Treat the flush as information. If you turn red after one or two drinks, you probably carry ALDH2*2. The lowest-risk choice is to drink little or not at all.
- Do not mask it. Skip antacids and "glow" pills taken to keep drinking.
- Never combine alcohol and tobacco. Smoking adds to the esophageal cancer risk of drinking.
- Talk to your doctor if you have been a regular drinker who flushes, and promptly if you have trouble swallowing. In Japan, flushers who drink are sometimes offered endoscopic screening.
- Use the alcohol-free options that holiday parties now have: alcohol-free beer, wine and spirits, kombucha, sparkling water with bitters.
Check your ALDH2 and ADH1B genes
rs671 is on most consumer DNA chips, so the answer is usually already in your raw data file. Our Complete report reads ALDH2 and ADH1B and explains what your combination means for drinking. For the full biology, read our guide to ALDH2 and alcohol metabolism.
Educational information, not medical advice. If you are worried about your drinking or your cancer risk, speak to a doctor.
References
- Brooks PJ, Enoch MA, Goldman D, Li TK, Yokoyama A. The alcohol flushing response: an unrecognized risk factor for esophageal cancer from alcohol consumption. PLoS Med. 2009;6(3):e1000050.
- Yokoyama A, et al. Esophageal cancer and aldehyde dehydrogenase-2 genotypes in Japanese males. Cancer Epidemiol Biomarkers Prev. 1998;7(11):971-976.
- Secretan B, Straif K, Baan R, et al. A review of human carcinogens, Part E: tobacco, areca nut, alcohol, coal smoke, and salted fish. Lancet Oncol. 2009;10(11):1033-1034.
- Li D, Zhao H, Gelernter J. Strong association of the alcohol dehydrogenase 1B gene (ADH1B) with alcohol dependence and alcohol-induced medical diseases. Biol Psychiatry. 2011;70(6):504-512.
- Office of the US Surgeon General. Alcohol and Cancer Risk: The U.S. Surgeon General's Advisory. January 2025.
- Annenberg Public Policy Center. Awareness grows of cancer risk from alcohol consumption. April 2025.