ACETALDEHYDE

📋 Quick facts

Description: ACETALDEHYDE — FRAGRANCE.

All Functions: FRAGRANCE

Quick Facts:

• Category: other
• Regulatory Note: Prohibited in the EU

Proven Benefits At A Glance:

• Acetaldehyde is a byproduct of alcohol metabolism in the body, produced when enzymes break down ethanol
• High acetaldehyde exposure is linked to cancers of the digestive tract and upper airways, especially in people who drink alcohol or smoke
• Genetic variations affect how efficiently your body processes acetaldehyde, influencing flushing responses and cancer risk
• Acetaldehyde can appear as an impurity in alcohol-based hand sanitizers at levels that may pose health concerns with frequent use
• The amino acid cysteine can bind acetaldehyde and may help reduce its harmful effects

⚗️ Chemical Overview

Acetaldehyde can cause cancer according to an independent committee of scientific and health experts. Acetaldehyde appears as a clear colorless liquid with a pungent choking odor. Flash point -36 °F. Boiling point 69 °F. Density 6.5 lb / gal. Vapors are heaver than air and irritate the mucous membranes and especially the eyes. Used to make other chemicals. Acetaldehyde is the aldehyde formed from acetic acid by reduction of the carboxy group. It is the most abundant carcinogen in tobacco smoke. It has a role as an electron acceptor, a mutagen, a carcinogenic agent, a teratogenic agent, an oxidising agent, a mouse metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite, a human metabolite and an EC 3.5.1.4 (amidase) inhibitor.

Source(s): CAMEO Chemicals, ChEBI, California Office of Environmental Health Hazard Assessment (OEHHA), via PubChem

📊 Comedogenicity

🛡️ Safety rating

Safety tier is a starting heuristic from regulatory status and comedogenic rating, not a dermatological verdict — see our Terms for the full disclaimer. Research confidence reflects how many real cited studies back this ingredient, not the strength of their findings.

🤰 Pregnancy Safety Note

Listed in California Safe Cosmetics Program as carcinogen or reproductive toxicant

🌍 Regulatory Status

💧 Skin Type Compatibility

⚠️ Don’t Combine With

📚 Research & Evidence

🔬 The Science

Acetaldehyde is a toxic intermediate compound created when your body metabolizes alcohol. It’s also a contaminant found in some commercial products. Here’s what the research shows:

#1: Acetaldehyde and cancer risk — Strong evidence indicates that local acetaldehyde exposure is a major factor behind gastrointestinal cancers, particularly in people who drink alcohol or smoke (Novartis Found Symp, 2007). The chemical appears to play a role in the etiology of liver cirrhosis and may contribute to other pathological developments including brain damage, cardiomyopathy, pancreatitis, and fetal alcohol syndrome (Alcohol Clin Exp Res, 2001). #2: How your genes affect acetaldehyde processing — A key enzyme called aldehyde dehydrogenase 2 (ALDH2) converts acetaldehyde to acetic acid during alcohol metabolism.

Genetic variants in ALDH2 significantly impact how efficiently your body clears acetaldehyde. For example, the rs671 variant (common in East Asian descendants) causes a 6-fold increase in acetaldehyde levels after alcohol consumption compared to people with the standard variant, while two newly identified variants (R101G and R114W) cause 2-fold increases (J Transl Med, 2024). These genetic differences directly correlate with facial flushing, increased heart rate, and elevated cancer risk. #3: Acute physiological responses — Elevated acetaldehyde during alcohol intoxication triggers vasodilation (blood vessel widening) associated with increased skin temperature, facial flushing, increased heart and respiration rate, lowered blood pressure, dry mouth or throat, nausea, and headache (Alcohol Clin Exp Res, 2001).

Interestingly, acetaldehyde creates both unpleasant aversive reactions that discourage excessive drinking and euphoric sensations that may reinforce it. #4: Acetaldehyde in hand sanitizers — Acetaldehyde appears as an impurity in alcohol-based hand sanitizers. A 2025 analysis of 85 commercial products in Taiwan found mean acetaldehyde concentrations of 22.39 μg/g, exceeding US FDA interim limits (Toxics, 2025). Children aged 2-11 who frequently use these products showed the highest non-carcinogenic and cancer risk from dermal exposure. #5: Protective strategies — Research suggests cysteine, an amino acid, can bind acetaldehyde efficiently by forming a stable compound called thiazolidine-carboxylic acid, potentially protecting against acetaldehyde toxicity (Novartis Found Symp, 2007).

Special cysteine formulations (lozenges and chewing gums) have been developed to bind acetaldehyde from smoking and alcohol consumption in the oral cavity. Additionally, an antiseptic mouthwash containing chlorhexidine can significantly reduce acetaldehyde production from ingested ethanol in the oral cavity. The sources show clear limitations: there is no direct skincare application of acetaldehyde discussed in these abstracts. The research focuses on acetaldehyde as a metabolic byproduct from alcohol consumption, an impurity in hand sanitizers, and a cancer risk factor—not as an intentional skincare ingredient.

📄 Related Research

Matched by search — not necessarily verified support for every statement above.

• Salaspuro V (2007). Pharmacological treatments and strategies for reducing oral and intestinal acetaldehyde. Novartis Found Symp.
• Zhou W et al. (2025). Acetaldehyde dehydrogenase 1A1 upregulation drives dacomitinib-induced skin toxicity through mitochondrial dysfunction and keratinocyte apoptosis. Cell Signal.
• Rwere F et al. (2024). Uncovering newly identified aldehyde dehydrogenase 2 genetic variants that lead to acetaldehyde accumulation after an alcohol challenge. J Transl Med.
• Eriksson CJ (2001). The role of acetaldehyde in the actions of alcohol (update 2000). Alcohol Clin Exp Res.
• Cheng CA et al. (2025). Presence and Dermal Exposure to Benzene and Acetaldehyde in Hand Sanitizers Available in Taiwan. Toxics.

🧴 Products Containing ACETALDEHYDE