Body & Beauty / Compounds / Hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral)

Hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral) on your skin: a safety profile

High risk

(People-specific data is limited; this page draws from human adult context.) Strong skin sensitizer; reproductive toxicant suspect; BANNED in EU cosmetics since August 2021 (REACH Annex II); one of the most potent fragrance contact allergens identified

What is hydroxyisohexyl 3-cyclohexene carboxaldehyde (lyral)?

The IUPAC name is 4-(4-hydroxy-4-methylpentyl)cyclohex-3-ene-1-carbaldehyde.

Also known as: 4-(4-hydroxy-4-methylpentyl)cyclohex-3-ene-1-carbaldehyde, 4-(4-Hydroxy-4-methylpentyl)-3-cyclohexene-1-carboxaldehyde, hydroxyisohexyl 3-cyclohexene carboxaldehyde, Liral.

IUPAC name
4-(4-hydroxy-4-methylpentyl)cyclohex-3-ene-1-carbaldehyde
CAS number
31906-04-4
Molecular formula
C13H22O2
Molecular weight
210.31 g/mol
SMILES
CC(C)(CCCC1=CCC(CC1)C=O)O
PubChem CID
91604

Risk for people

High risk

Strong skin sensitizer; reproductive toxicant suspect; BANNED in EU cosmetics since August 2021 (REACH Annex II); one of the most potent fragrance contact allergens identified

Regulatory consensus

3 regulatory and scientific bodies have classified Hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral). The classifications differ — that's the data.

AgencyYearClassificationNotes
EU2024Banned in cosmetics (REACH Annex II)
IFRA2020prohibitionIFRA prohibited — extreme sensitizer
EU_COSMETICS2022bannedEU banned in cosmetics March 2022

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where you encounter hydroxyisohexyl 3-cyclohexene carboxaldehyde (lyral)

  • Personal Care — perfume, deodorant, soap, shampoo, lotion
  • Fragrance — perfume, cologne, scented personal care products, household fragrance products, candles
    Identified in Fragrance Ingredient Safety Priority Research database (2,325 ingredients)

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral):

  • Floralozone (Floramat)
    Trade-offs: Powerful oxidant; effective for taste/odor and micropollutants; decomposes to oxygen (no residual); forms bromate in bromide-containing water; capital cost moderate; operational complexity higher than chlorination.
    Relative cost: 1.2-2×
  • Cyclamen aldehyde
    Trade-offs: Alternative fragrance ingredient; individual safety profile should be assessed per IFRA standards; sensitization potential varies by compound; patch testing recommended for sensitive individuals.
    Relative cost: 1.2-2×
  • Lilac aldehydes
    Trade-offs: Alternative fragrance ingredient; individual safety profile should be assessed per IFRA standards; sensitization potential varies by compound; patch testing recommended for sensitive individuals.
    Relative cost: 1.2-2×

Frequently asked questions

What products contain hydroxyisohexyl 3-cyclohexene carboxaldehyde (lyral)?

Hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral) appears in: perfume (Personal care); deodorant (Personal care); perfume (Fragrance); cologne (Fragrance).

Why do regulators disagree about hydroxyisohexyl 3-cyclohexene carboxaldehyde (lyral)?

Hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral) has been classified by 3 agencies including EU, IFRA, EU_COSMETICS, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.

See Hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral) in the body app

Look up products containing hydroxyisohexyl 3-cyclohexene carboxaldehyde (lyral), compare to alternatives, and explore the full data record.

Open in body View raw API data

Sources (1)
  1. PubChem Compound Database (2026) — database

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →