Linalool in shampoos and conditioners causes eczema

Linalool is a fragrance ingredient found naturally in lavender, mint, and other plants. It breaks down when it comes in contact with oxygen and can cause allergy.

Manufacturers do include other substances in the products to delay this oxidation process, but allergic substances can still be formed from linalool when it is stored.

Oxidised linalool was added at patch testing for more than 3,000 patients who wanted to find out what was causing their eczema. Eczema is an acute or chronic inflammation of the skin, characterised by redness and itching.

Between five percent and seven percent proved to be allergic to the oxidised form of the fragrance ingredient, according to the study.

"Linalool is found in 60-80 percent of perfumed hygiene products... and it can be difficult for people who are allergic to avoid these products," said Johanna Br�red Christensson. She is a dermatologist at Sahlgrenska Academy, University of Gothenburg, Sweden, and author of the thesis.

"I would suspect that about two percent of the complete population of Sweden are allergic to air oxidised linalool. That may not sound very much, but it is serious since linalool is so widely used as a fragrance ingredient," she said.

Nickel is by far the most common substance that causes eczema, but the thesis shows that oxidised linalool occupies third place in the list, after nickel and cobalt.

Copyright 2009 by Ians