Butylphenyl methylpropional is a synthetic fragrance chemical most commonly known by its trade name, Lilial. It has a strong floral scent reminiscent of lily of the valley and was one of the most widely used fragrance ingredients in consumer products for decades. Since March 2022, it has been banned from cosmetics sold in the European Union after being classified as harmful to reproductive health.
Chemical Identity and Scent Profile
The full chemical name is 3-(4-tert-butylphenyl)-2-methylpropanal, with a molecular formula of C14H20O. You might also see it listed as lily aldehyde, Lilestralis, or p-tert-butyl-alpha-methylhydrocinnamaldehyde on ingredient labels or safety data sheets. It belongs to a class of chemicals called phenyl propanaldehydes, which share a reactive aldehyde group that gives them their characteristic scent properties.
The ingredient produces a strong, clean floral odor that perfumers valued for its ability to replicate the smell of fresh lily of the valley. This made it a staple in fine fragrances, but it was equally common in everyday products: shower gels, deodorants, perfumes, cleaning agents, and air fresheners all frequently contained it.
Why the EU Banned It
The European Union banned butylphenyl methylpropional from cosmetic products effective March 1, 2022, under Regulation (EU) No. 2021/1902. The reason was its classification as a CMR substance, specifically as reprotoxic, meaning it can harm fertility or fetal development. This classification automatically triggers a ban under EU cosmetics law, which prohibits CMR-classified substances from being used in products applied to the body.
The UK’s Office for Product Safety and Standards also issued reminders to cosmetics manufacturers about the ban, underscoring that products still containing Lilial should not be sold. If you purchased cosmetics before 2022, particularly European-made perfumes or body care products, they may still contain this ingredient. Checking ingredient lists for “butylphenyl methylpropional” is the simplest way to identify it.
Skin Sensitization Risk
Beyond reproductive concerns, butylphenyl methylpropional is also an established contact allergen. Clinical data from multiple independent dermatology centers have documented it as a fragrance ingredient with a moderate prevalence of sensitization, with between 10 and 100 reported cases of allergic contact dermatitis across published studies. That places it in the same sensitization category as benzyl alcohol, benzyl benzoate, and amyl cinnamal.
For people with fragrance allergies, exposure typically causes red, itchy, or inflamed skin at the site of contact. Patch testing at a dermatologist’s office can confirm whether this specific chemical is a trigger. Because it was so widespread in consumer products, people with unexplained contact dermatitis from perfumed products may have been reacting to Lilial without knowing it.
Environmental Breakdown
One area where butylphenyl methylpropional performs relatively well is environmental persistence. According to an evaluation by Australia’s industrial chemicals regulator, the chemical is not persistent, not bioaccumulative, and readily biodegradable in water based on standard OECD testing. It also degrades rapidly in the atmosphere.
That said, it does carry some aquatic toxicity. It is classified as “toxic to aquatic life” in the acute category, with lethal concentrations for zebrafish at around 2 mg/L over 96 hours and effects on water fleas at about 10.7 mg/L over 48 hours. In practical terms, the chemical can harm aquatic organisms at relatively low concentrations, but because it breaks down quickly, it does not accumulate in waterways or build up in the food chain. Risk assessments comparing predicted environmental concentrations to safe thresholds found the risk quotient for Lilial at 0.52, which falls below the level of concern (a value of 1 or higher would indicate unacceptable risk).
What Replaced It
The fragrance industry has been reformulating products since the ban. Replacing Lilial is not straightforward because its particular floral quality was hard to replicate with a single alternative molecule. Fragrance manufacturers have developed proprietary blends to approximate the same lily of the valley character. One example is a base called Mugal, created by Spanish fragrance house Bordas, described as a fresh floral-aquatic composition designed to fill the gap Lilial left in formulations.
Most major brands have already completed reformulation, so products currently on shelves in the EU and UK should be Lilial-free. In the United States, butylphenyl methylpropional has not been banned at the federal level, so it may still appear in products sold there. If you want to avoid it, look for it by name on the ingredient list, or check for “Lilial” if the product uses trade names.
How to Identify It on Labels
EU cosmetics regulations have long required individual fragrance allergens to be listed by name on product labels rather than hidden under the generic term “fragrance” or “parfum.” Butylphenyl methylpropional is one of these mandatory disclosure ingredients. On older products, you will typically find it near the end of the ingredient list. It may appear as any of its synonyms: butylphenyl methylpropional, Lilial, or lily aldehyde.
In countries without mandatory fragrance allergen labeling, the chemical can be bundled into the catch-all “fragrance” designation, making it impossible to know whether a product contains it without contacting the manufacturer directly.