ALDH2: the alcohol flush, and the risk behind it
The flush after a drink isn't a quirk. It's your body telling you a toxin is piling up. The research backs that up.
When you drink, your body turns the alcohol into acetaldehyde, a toxic byproduct, then breaks that down with an enzyme called ALDH2. The rs671 variant cripples that second step. Acetaldehyde sticks around, and that's the flush you feel: the red face, the queasiness, the pounding heart. That same backup is why steady drinking carries a much higher esophageal cancer risk for people who carry the variant.
Alcohol hits you harder than it hits most people. Your ALDH2 variant slows the breakdown of acetaldehyde, the toxic step between alcohol and a hangover, which is what causes the flush. It also means regular drinking carries a much higher esophageal cancer risk for you. The reliable move is to drink less or skip it. This is a warning light, not a diagnosis, so talk it through with your doctor.
PubMed 37795758 · ALDH2 rs671, alcohol & esophageal squamous cell carcinoma
What ALDH2 does
No pill fixes this. The thing that actually works is drinking less, or not at all. Acetaldehyde is classed as a carcinogen, and carriers who drink heavily sit at the high end of the risk.
Think of this as a warning light, not a verdict. That said, it's one of the most solidly proven gene-and-lifestyle links we have in this whole field. Bring it up with your doctor.
Your variants, decoded
The A allele builds an enzyme that barely works. One copy is enough to give you the flush.
| GG | Two working copies. This variant won't make you flush. |
| GA | One copy (*1/*2). You'll flush — and if you keep drinking anyway, this is actually the higher-risk group for esophageal cancer: you keep just enough enzyme to tolerate alcohol while toxic acetaldehyde builds up. |
| AA | Two copies (*2/*2). The enzyme is essentially dead, so the flush is severe — most people who carry it simply can't drink, which keeps real-world risk low. The danger appears only if alcohol is pushed past the reaction. |
We show genotypes on the forward strand and ignore letter order. Your own export may print the complementary letters. Same result either way.
See this matched to your own DNA, free.
Upload your 23andMe or AncestryDNA file and you'll get your actual ALDH2 result, plus every other variant worth acting on. Every line cited. Your file is never stored.
Questions
Is the alcohol flush dangerous?
The flush is acetaldehyde building up in your blood. On its own it's uncomfortable, not dangerous. The real worry is the long game. Drinking regularly with an ALDH2 variant raises esophageal cancer risk, and cutting back is what helps.