A synthetic aromatic aldehyde frequently utilized for its intense lily-of-the-valley and cyclamen-like scent. Once a staple in global perfumery, regulatory bodies have largely restricted or banned its use due to its well-documented role as a potent skin sensitizer and allergen.
- INCI Name:
- Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde
- Chemical/Scientific Name:
- 4-(4-Hydroxy-4-methylpentyl)cyclohex-3-ene-1-carbaldehyde
- Common Aliases:
- Lyral, HICC, Kovanol, Mugonal
| Category: | Scents |
| Source Origin: | Synthetic |
| Comedogenic Rating: | N/A |
| Primary Industries: | Fine Fragrance, Personal Care, Household Detergents |
| Solubility: | Oil-soluble, Alcohol-soluble |
At a Glance: Properties & Effects
| Texture Enhancement | |
| Formula Stability | |
| Irritation Risk | |
| Comedogenicity |
- Primary Benefits:
- Provides a long-lasting, sophisticated floral Aroma to cosmetic bases.
- Functions as a masking agent to neutralize the unpleasant natural odors of raw chemical materials.
- Potential Risks:
- High prevalence of contact allergy and dermatological sensitivity.
- Induces skin redness, itching, and dermatitis in sensitized individuals.
- Prohibited in several major cosmetic markets, including the European Union and United Kingdom.
Biological Action & Cosmetic Profile
Molecularly, this aromatic aldehyde serves no physiological purpose in skin health or barrier maintenance. Its primary function is olfactory, characterized by high substantivity, meaning the scent remains on the skin for extended periods after application. Unlike many natural extracts, this synthetic compound offers a consistent scent profile that does not degrade easily when exposed to varying temperatures or pH levels within a Fragrance formulation.A significant concern arises from its chemical structure, which allows it to act as a pro-hapten. Once the molecule penetrates the stratum corneum, it can undergo oxidation or enzymatic activation, forming reactive species that bind to skin proteins. This protein-binding process triggers an immune response, leading to the development of allergic contact dermatitis. Clinical data indicates that it is one of the most common causes of fragrance-related allergies, second only to oakmoss and isoeugenol in certain population studies.
Broader Applications & Origins
Laboratories first introduced this compound to the commercial market in the 1960s as a reliable alternative to volatile natural floral oils. Its stability made it an ideal candidate for complex Parfum compositions, laundry detergents, and fabric softeners. While it dominated the “fresh” and “clean” scent categories for decades, the rise in clinical sensitivity cases prompted the industry to seek safer synthetic replacements that mimic the same floral notes without the high risk of immunogenicity.
Routine Integration
- Synergies:
- Works effectively alongside fixatives like Benzyl Alcohol to prolong scent longevity.
- Blends seamlessly with other synthetic floral components to create complex bouquets in luxury products.
- Conflicts:
- Highly reactive with sensitive or compromised skin types.
- Should be avoided in products intended for the eye area or mucous membranes.
Clinical Consensus & Safety
Dermatological consensus has shifted decisively against the use of this ingredient in topical applications. The Scientific Committee on Consumer Safety (SCCS) issued an opinion stating that the high number of sensitized consumers rendered the substance unsafe for use in cosmetics. Consequently, EU Regulation 2017/1410 officially banned the ingredient, prohibiting any products containing it from being placed on the market as of August 2019, with a total withdrawal by August 2021. In regions where it remains legal, such as the United States, it must be explicitly listed on the label if concentrations exceed 0.001% in leave-on products, rather than being hidden under the generic term “fragrance.”
Is Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde safe for all skin types?
No, it is considered one of the most frequent allergens in skincare. Individuals with reactive skin or a history of eczema should strictly avoid products containing this compound to prevent flare-ups of contact dermatitis.
Why do some products still list Lyral on their labels?
Regulation varies by country. While the EU and UK have banned the substance, other markets may still allow it, provided it is declared in the INCI list once it exceeds specific concentration thresholds.
How can I identify this ingredient if it’s not listed by its full name?
Check for the common trade name “Lyral” or the abbreviation “HICC” on industrial safety data sheets, though in consumer cosmetics, the full INCI name “Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde” is the legal requirement for disclosure.