[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Acetaldehyde

[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# 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

Loading the 3D model…

## 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.

**Also called**
Ethanal

**Formula**
C₂H₄O

**PubChem**
[CID 177](https://pubchem.ncbi.nlm.nih.gov/compound/177)

## Structure

- A methyl group bonded to an aldehyde group (–CHO).

## Clinical notes

- 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.

## Pathways

- [Ethanol metabolism](https://durgical.com/en/biochemistry/pathways/ethanol-metabolism/)

## Related conditions

- [Disulfiram–ethanol reaction](https://durgical.com/en/conditions/disulfiram-ethanol-reaction/)
- [Alcoholic liver disease (biochemistry)](https://durgical.com/en/conditions/alcoholic-liver-disease/)
- [Oesophageal cancer](https://durgical.com/en/conditions/oesophageal-cancer/)

## Related

- [Ethanol](https://durgical.com/en/biochemistry/molecules/ethanol/)
- [Aldehyde dehydrogenase 2 (ALDH2)](https://durgical.com/en/biochemistry/enzymes/aldehyde-dehydrogenase-2/)
- [Alcohol dehydrogenase (ADH)](https://durgical.com/en/biochemistry/enzymes/alcohol-dehydrogenase/)
- [Cytochrome P450 2E1 (CYP2E1, MEOS)](https://durgical.com/en/biochemistry/enzymes/cytochrome-p450-2e1/)

## Test yourself

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.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/biochemistry/molecules/acetaldehyde/)

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)](https://pubchem.ncbi.nlm.nih.gov/compound/177) (PubChem, NCBI, 2026); [Ethanol oxidation](https://reactome.org/PathwayBrowser/#/R-HSA-71384) (Reactome, 2026); [Alcohol use disorder: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/alcohol-use-disorder/) (MedlinePlus, US National Library of Medicine, 2026).

[← All of biochemistry](https://durgical.com/en/biochemistry/)

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/biochemistry/molecules/acetaldehyde/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/molecules/acetaldehyde/