Ingredient review
Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde
INCI: Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde
A synthetic fragrance that is a common allergen; many brands have phased it out due to safety regulations.
In plain English
This is a man-made scent ingredient that gives products a floral, lily-of-the-valley-like smell. It is one of the fragrance allergens that the European Union requires to be listed separately on labels because it can cause skin allergies in some people. Many cosmetic companies have stopped using it in favor of safer alternatives.
Review score
Safety, usefulness, and evidence
Higher-caution ingredient
The evidence base is relatively strong for its common cosmetic role.
Main practical flags: irritation is moderate; clogging risk is low.
- Source
- synthetic
- Evidence
- strong
- Irritation
- moderate
- Clogging risk
- low
Quick decision guide
Read the cautions before using
Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde can be useful, but watch for some irritation potential.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
moderateCan bother some users, especially with frequent use, damaged skin, or strong companion ingredients.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
strongThere is a stronger practical or research basis for the ingredient role described here.
What it is
A synthetic aromatic aldehyde used primarily as a fragrance ingredient to impart a floral scent.
How it works
It evaporates from the skin, releasing scent molecules that are detected by the nose. In a product, it simply adds fragrance and has no functional skincare benefit.
Pros
Pleasant floral scent
Adds a classic lily-of-the-valley note that many people enjoy in perfumes and scented lotions.
Widely studied
Its allergenicity is well-documented, so regulators have clear guidelines for safe use levels.
Cons and cautions
Common allergen
It is one of the most frequently reported fragrance allergens in patch tests, meaning it can cause red, itchy, or irritated skin in susceptible individuals.
Restricted in some markets
Due to its sensitizing potential, the EU has set strict concentration limits, and many brands have voluntarily removed it from their formulas.
Best for
- People who tolerate synthetic fragrances well
- Those using products where it is present at very low levels and have no history of fragrance allergy
Use caution if
- Anyone with known fragrance allergies or sensitive, reactive skin
- People with eczema or contact dermatitis
Usage tips
Safety summary
Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde is a well-known skin sensitizer and common allergen. It is considered safe for most people at very low concentrations, but individuals with fragrance allergies or sensitive skin should avoid it. Regulatory bodies in the EU have set strict limits on its use.
Research notes
Multiple studies confirm its role as a contact allergen, with positive patch test rates of 1-3% in dermatology clinics. The EU's Scientific Committee on Consumer Safety has classified it as a strong sensitizer, leading to restricted use.
Common label clues
- Typical concentration
- Typically used at very low levels (under 1%) in leave-on products
- Regulatory status
- Restricted in the EU as a fragrance allergen; must be listed on the label if present above certain levels. Not banned in the US but subject to safety reviews.
- Common uses
- Fragranced skincare, Perfumes, Body lotions, Hair care
- Environmental note
- As a synthetic compound, it is not biodegradable and may accumulate in the environment, though its impact is considered low due to small usage amounts.
Good to know
- This ingredient is also known by the trade name Lyral.
- It is one of the 26 fragrance allergens that must be individually listed on cosmetic labels in the European Union.
Common questions
What is Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde in beauty products?
This is a man-made scent ingredient that gives products a floral, lily-of-the-valley-like smell. It is one of the fragrance allergens that the European Union requires to be listed separately on labels because it can cause skin allergies in some people. Many cosmetic companies have stopped using it in favor of safer alternatives.
What does Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde do in a beauty product?
It evaporates from the skin, releasing scent molecules that are detected by the nose. In a product, it simply adds fragrance and has no functional skincare benefit.
Is Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde safe for most people?
Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde is a well-known skin sensitizer and common allergen. It is considered safe for most people at very low concentrations, but individuals with fragrance allergies or sensitive skin should avoid it. Regulatory bodies in the EU have set strict limits on its use.
Who should be careful with Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde?
Anyone with known fragrance allergies or sensitive, reactive skin People with eczema or contact dermatitis
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.