The use of hair-straightening products containing glyoxylic acid is associated with a risk for acute kidney failure because of the accumulation of calcium oxalate crystals in the kidneys. The observation was made by a team of French researchers who tested the suspected straightening product on animals. The product is believed to be the cause of several episodes of renal damage in a young woman.

“The results on mice are striking, “They develop extremely severe acute kidney failure within 24 hours of applying the straightening cream. Samples show the presence of calcium oxalate crystals in all renal tubules.”

Given the potential nephrotoxicity of glyoxylic acid through topical application, products containing this compound should be avoided and ideally withdrawn from the market, the researchers suggested in a letter published in The New England Journal of Medicine. 

Replacing Formaldehyde

Glyoxylic acid has recently been introduced into certain cosmetic products (such as shampoo, styling lotion, and straightening products), often as a replacement for formaldehyde, which is irritating and possibly carcinogenic. Glyoxylic acid is praised for its smoothing qualities. However, it is recommended to avoid contact with the scalp.

Cases of renal complications could be underdiagnosed, according to the researchers, who are preparing a nationwide survey. Renal failure can be silent. Among the signs that should raise concern are “scalp irritation accompanied by nausea or vomiting after a hair salon visit,”.

An Israeli team recently described 26 patients treated for acute renal injuries after hair straightening in hair salons. Biopsies revealed calcium oxalate crystals in the kidneys.

Glycolic Acid found to be a safe alternative to Glyoxylic Acid.