Jun 30, 2026 - Cosmetics
HairStraighteningProducts – HiddenDangers
Especially for people with very curly or frizzy hair, hair straighteners with long-lasting effects are often very popular. The Chemical and Veterinary Investigation Office (CVUA) in Karlsruhe examined a total of 14 hair straighteners in 2025. Five products were deemed harmful to health, two due to the presence of a prohibited substance (formaldehyde), eleven due to other deficiencies, and only three products were found to be unobjectionable.
A distinction is made between permanent straightening, which must grow out, and long-lasting straightening, which lasts 2 to 4 months. Hair straighteners that promise long-lasting straightening are often marketed under the names Brazilian/Keratin/Smoothing, and the risks for the user are often insufficiently described on the product. Manufacturers advertise with the active ingredient keratin, which is supposed to cause the straightening, but this is unlikely. To achieve the straightening, formaldehyde and glyoxylic acid are mainly used, which are not always labeled on the products.
Formaldehyde is prohibited in cosmetic products according to the European Cosmetics Regulation (EC) No. 1223/2009 Annex II, as it is a CMR substance (carcinogenic, mutagenic, toxic to reproduction).
Glyoxylic acid is currently being re-evaluated by the SCCS (Scientific Committee of the EU) for a requested maximum concentration of use of 16%. In connection with hair straighteners, the substance is also suspected, probably due to penetration through the skin, to be associated with acute kidney failure.
The CVUA particularly advises caution with products from the Internet, as product labeling is often incomplete, warnings are missing, and high concentrations of formaldehyde or glyoxylic acid can pose health risks. You can view the complete article on the CVUA Karlsruhe's website.
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