Perfume labels list specific allergens like linalool or limonene because EU and UK cosmetic regulation legally requires disclosure of certain fragrance substances known to cause skin sensitisation in a minority of people, so anyone with a known allergy or sensitive skin can check the label before buying or using a product.

The reasoning behind the rule

Fragrance is usually protected as a trade secret, brands aren’t required to reveal their full formula, but regulators carved out an exception for a specific list of substances, covered in our answer on the EU’s listed fragrance allergens, because dermatological research identified them as more likely than average to cause contact allergies or irritation in susceptible individuals. Listing them doesn’t mean the product is unsafe for most people; it means regulators decided the public benefit of disclosure, for that specific minority, outweighed the industry’s usual confidentiality around full formulas.

In practice, most of these compounds occur naturally in common raw materials, linalool in lavender, limonene in citrus peel, so a perfume doesn’t need harsh synthetic chemistry to trigger the listing; it’s just as likely to come from natural essential oils as from lab-made ingredients. Our perfume ingredients guide explains labelling and safety fully, and the complete guide to perfume covers formulation basics. This is also why two perfumes with a similar overall smell can list quite different named allergens, since the specific raw materials used to build a similar effect can vary considerably.