Do keratin treatments release formaldehyde into the air at the salon?
Yes. Heat-styled keratin smoothing creams release airborne formaldehyde even from "formaldehyde-free" formulas that use methylene glycol.
What's actually in it
Keratin smoothing treatments include either straight formaldehyde or its sneaky cousins methylene glycol, formalin, glyoxylic acid, or DMDM hydantoin. The "formaldehyde-free" label often just means the cream uses one of these instead. When the stylist blow-dries and flat-irons the cream, the chemicals release real formaldehyde gas into the salon air.
What the research says
A 2026 study in J Natl Cancer Inst followed thousands of women who used hair straighteners and relaxers. Frequent users had higher rates of certain non-reproductive cancers. The risk was bigger for people who started young and used the products several times a year. OSHA flagged airborne formaldehyde levels above the legal limit in salons running daily keratin services.
If you do keratin, pick a salon with strong ventilation and ask about the brand's actual formaldehyde content. Skip "formaldehyde-free" formulas with methylene glycol. Cezanne Hair Smoothing Treatment uses a different chemistry. For at-home styling, try a hair mask, blow-dry brush, or plain heat tools. The OSHA Hair Salon hazard alert lists what to watch for.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Use of hair straighteners and chemical relaxers and incidence of non-reproductive cancers | J Natl Cancer Inst | 2026 |
What to use instead
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