Researchers have shown that a common fragrance chemical which is one of the main constituents of the lavender oil can cause allergic eczema.
Linalyl acetate is not on the list of allergenic compounds by the EU Cosmetics Directive.
A team from Sahlgrenska Akademin at the University of Gothenburg in Sweden has found that it can react with oxygen in the air to form strongly allergenic hydroperoxides.
Thus, linalyl acetate can be a common cause of contact allergy.
The study included 1,717 participants who were being assessed for eczema related to contact allergy.
Approximately 2% of them had allergic reactions to oxidized linalyl acetate.
"That may seem like a small percentage but it is approximately the same result as for the fragrance compounds listed in the Cosmetics Directive," said Lina Hagvall, one of the researchers.
Because the substance is not mentioned on cosmetic products, consumers have trouble avoiding it, which can turn allergic eczema into a more severe long-term condition.
In accordance with the EU Cosmetics Directive, makeup, ointments, shampoo, deodorants, toothpaste and other products must mention the ingredients in order for consumers to avoid the substances which they are allergic to.
The study has been published in the journal Contact Dermatitis.