A fragrance allergen is a specific scent ingredient known to cause allergic skin reactions in some people. EU and UK cosmetic rules name a set list of these substances. When one of them is present in a product above a set level, it has to be named in the ingredient list so that sensitised people can avoid it.

It must be declared when its concentration in the finished product is above 0.001% in a leave-on product, such as a serum or cream, or above 0.01% in a rinse-off product, such as a shampoo or wash. Below those levels it does not need naming separately on the label.

Multiply the percentage of the allergen in the fragrance or essential oil by the percentage of that material in your formula, then divide by 100. If the same allergen comes from more than one material, add those amounts together before comparing the total to the threshold. The calculator above does this for you across every material you add.

From your supplier. It is usually included in the material safety data sheet, often in section 3 or near the end, or provided separately as an IFRA allergen declaration or an allergen statement. It lists each allergen present in that material along with its percentage.

The original EU list named 26 fragrance allergens. Regulation (EU) 2023/1545 expanded it to more than 80 substances and groups. Products newly placed on the EU market need to comply by 31 July 2026, and products already on the market by 31 July 2028.

Not necessarily. The EU expanded its list under Regulation 2023/1545. The UK keeps its own retained cosmetics regulation and has not adopted that expansion, so the two lists can differ. Always confirm the rules for the market you are selling into and work with your safety assessor.