The use of formaldehyde in keratin treatments has made skeptics of clients, stylists and health experts alike. Whether a lower concentration—at or beneath the recommended .2 percent—is completely safe is hotly contested. Concentrations ten to 20 times higher are not unheard of. Some clients have experienced discomfort and damage to scalp and hair due to keratin treatments.

During the procedure

Salons should use keratin treatments in well-ventilated areas that utilize fans and open air flow. Masks are also recommended but not always adhered to. Formaldehyde and its derivatives—which are found in most of the effective keratin treatments—release strong fumes.


Health experts speculate that although the treatments are said to be “keratin-based,” it’s the formaldehyde which does the straightening, according to Keratin itself lacks the ability to break disulfide bonds in the hair, necessary for changing hair’s shape for months, the way these treatments can.


Formaldehyde and its derivatives give off a noxious gas that can burn and sting the eyes in the short-term. Many women have complained about these symptoms during the process, but no long-term or permanent damage has been reported.


Formaldehyde can aggravate allergies. One study of people with asthma found they may be more sensitive to the effects of inhaled formaldehyde with high concentrations triggering asthma attacks, according to the U.S. Environmental Protection Agency.

Skin and hair

The skin absorbs formaldehyde rather quickly. Skin irritation has been reported on the scalp, even though stylists are instructed to keep chemicals off of it. Some clients report shedding from the roots and increased breakage, which is likely with any chemical processing; however, keratin treatment often claims to be a “safe” alternative.

Cancer risks

A 1980 lab study on rats showed that formaldehyde exposure caused nasal cancer in rats, according to the National Cancer Institute. Other studies have revealed a higher risk of upper respiratory cancer than other types of cancers in people who are overly exposed to the toxin. Clients who receive the treatments every few weeks and stylists utilizing it on a daily business may have increased risk.