Acetaldehyde !

The first product of alcohol in the liver: highly reactive, it causes hangover symptoms, flushing and part of the liver damage and cancer.

Updated 2026-11-01

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Key facts

CH₃–CHO: an aldehyde that ALDH2 quickly oxidises to acetate.
It binds proteins and DNA (adducts): it damages microtubules, mitochondria and DNA repair.
IARC classifies it as a group 1 carcinogen when it comes from alcoholic drinks.
It builds up with disulfiram or the ALDH2*2 variant: flushing, nausea, tachycardia and hypotension.

It releases histamine and dilates vessels: the facial flushing of the «Asian flush».
Its protein adducts activate immunity and stellate cells: liver fibrosis.
Saliva and oral bacteria also make it: link with mouth, pharynx and oesophageal cancer.

Think of the answer, then tap the question to see it.

Which enzyme removes acetaldehyde, and in which compartment?

ALDH2, in the hepatocyte mitochondrion.

Why is acetaldehyde carcinogenic?

It forms DNA adducts and impairs DNA repair.

What symptoms does its build-up cause?

Flushing, headache, nausea, vomiting, tachycardia and hypotension.

Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: Acetaldehyde (CID 177) (PubChem, NCBI, 2026); Ethanol oxidation (Reactome, 2026); Alcohol use disorder: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026).

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Representative model, for educational purposes only.