If you flush when you drink, you probably already suspect something genetic is going on. You're right. And in 2026, confirming it is easier than most people think.

What You're Testing For

ALDH2 deficiency is caused by a specific variant in the ALDH2 gene — known as ALDH2*2. People who inherit one copy of this variant produce an ALDH2 enzyme with reduced activity. People who inherit two copies produce an enzyme that barely functions at all.

The variant affects how your liver processes acetaldehyde, a toxic byproduct of alcohol metabolism. With deficient ALDH2, acetaldehyde builds up in the bloodstream after drinking — causing flushing, racing heart, nausea, and headaches.

How to Test

Consumer DNA testing. 23andMe includes ALDH2 variant analysis in their health + ancestry kits. You provide a saliva sample, send it off, and receive results covering hundreds of genetic variants including ALDH2*2 status. It will tell you whether you have zero, one, or two copies of the variant — which corresponds roughly to no deficiency, partial deficiency, or full deficiency.

AncestryDNA raw data can also be analysed for ALDH2 variants using third-party tools, though this is a more technical process and less user-friendly for most people.

Clinical genetic testing. If you want a medical-grade result — for example, as part of a broader health assessment — a GP or genetic counsellor can arrange targeted genetic testing. This is more expensive and less accessible than consumer testing, but may be appropriate in some circumstances.

The informal test. Honestly? If you consistently flush red after one or two drinks, and you have East Asian heritage, the probability that you carry ALDH2*2 is high enough that many clinicians would treat it as a working assumption without formal testing. The test is most useful for understanding severity — one copy versus two — and for people who want a definitive answer.

What the Result Tells You

Testing tells you your genotype — your genetic status. What it doesn't tell you is exactly how you'll respond to any given amount of alcohol, because other factors (body weight, food consumption, hydration, sleep, concurrent medications) all affect the real-world experience.

A result showing you have two copies of ALDH2*2 indicates that your enzyme activity is very low and your acetaldehyde exposure when drinking is substantially elevated. That's clinically meaningful — it's information worth having when thinking about long-term health.

A result showing one copy means partial function — your experience of flush will typically be less severe than someone with two copies, though it varies.

Why It's Worth Knowing

Understanding your ALDH2 status helps you make informed decisions about alcohol consumption — not just about comfort, but about long-term health. People with ALDH2 deficiency who drink regularly face an elevated risk of oesophageal cancer due to sustained acetaldehyde exposure. Knowing you have the variant is an argument for taking acetaldehyde management seriously, not just for hiding the red face.

Take the Next Step with iBlush

Once you know your ALDH2 status, the goal shifts to managing acetaldehyde exposure. iBlush products are formulated to support acetaldehyde clearance — working with your body's chemistry rather than just masking the flush. Find your format at iblushshop.com.

P.S. We did the research so you don't have to: 

1. The ALDH2*2 (rs671) variant is the specific genetic mutation tested for in consumer DNA kits. It is predominantly found in East Asian populations and is essentially absent among Europeans. Source: Genetic Polymorphisms of the Mitochondrial Aldehyde Dehydrogenase ALDH2 Gene, PMC. PMC
2. ALDH2*2 homozygotes have almost no ALDH2 enzyme activity. Heterozygotes have been reported to have up to ~80% reduced activity compared to those with two functional copies of the gene. Source: Slaney, C. et al. (2025). Alcohol, Clinical and Experimental Research. Wiley
3. A two-question questionnaire has been shown to predict ALDH2*2 genotype in East Asian populations with approximately 90% sensitivity and 88% specificity, suggesting the flushing response itself is a reliable indicator. Source: Brooks, P.J. et al. (2009). The Alcohol Flushing Response: An Unrecognized Risk Factor for Esophageal Cancer. PLOS Medicine. PMC
4. People with ALDH2 deficiency who drink regularly face an elevated risk of esophageal cancer due to sustained acetaldehyde exposure — making knowledge of genotype clinically meaningful. Source: ALDH2 Polymorphism and Alcohol-Related Cancers in Asians: A Public Health Perspective. PMC. PMC