Danger: Brazilian straightening can cause acute kidney failure, warns the Academy of Medicine

Lissage brésilien : alerte des risques d’insuffisance rénale aiguë

According to the Academy of Medicine, the practice of Brazilian straightening, a chemical process used to straighten hair, is the cause of acute kidney failure. In question, the glyoxylic acid contained in the products.

The Academy of Medicine warns this Friday June 7 in a press release on the risks associated with chemical hair straightening. This practice, known as Brazilian straightening, is carried out using chemical agents. Formaldehyde was first used but, classified as carcinogenic, was replaced in 2013 by glycolic acid derivatives, notably glyoxylic acid. "In the United States, in 1998, the Cosmetic Ingredient Review considered these agents ‘safe’ for short use, concentration ≤ 30% and a final formulation pH &age; 3, without however justifying these limits, notes the Academy.

An observation despite compliance with the maximum authorized concentration

According to several scientific articles, these products present health risks. "In 2023, lesions of regressive acute renal failure with presence< strong> of calcium oxalate crystals in kidney biopsies were described in 26 young patients, after a Brazilian-style hair straightening procedure, which is confirmed by a recent observation reporting the case of a 26-year-old woman, with no medical history, who presented three consecutive episodes of regressive acute renal failure after hair straightening", we read in the press release.

In question ? The formation of crystals of oxalic acid in the renal tubules, after absorption by the skin and the scalp of the product. It is also specified that the product used by the 26-year-old patient contained 10% glyoxylic acid, i.e. a concentration well below the 30% product concentration not to be exceeded.

A substance also used for peels

The causal link was demonstrated in mice with the application to the skin of a smoothing product containing 10% glyoxylic acid. After 24 hours, the crystals were found in the urine of animals that had received the cream. None in control mice to which a control cream had been applied.

Glyoxylic acid is also used in facial peels – chemical practice which consists of removing dead cells from the skin – at concentrations sometimes close to 30%. "The absorption of glycolic acid by the skin depends on the pH of the product, its concentration, the duration of exposure to the skin and the lipophilic properties of the product. An observation of acute renal failure, in a kidney transplant patient 4 years ago, was described after 5 facial peels with glycolic acid (at a concentration between 40 and 70%). Kidney biopsy revealed the presence of oxalate crystals.

Need to inform and assess the risk

While the use of these cosmetic products is largely democratized among women and also among men, the Academy of Medicine formulates these four recommendations:

disseminate alert and information messages to health professionals, hairdressing salons and businesses selling cosmetic products based on these acids, in order to make them aware of these risks of acute kidney failure appearing within 24 to 48 hours after the technical procedures; inform users of the risks in the event of frequent use of these straightening products, and of the signs of acute renal failure, in particular acute abdominal pain, nausea, rapid onset vomiting. do not perform hair straightening or "peeling" in cases of damage to the scalp or facial skin, which increases the penetration of glyoxylic acid and glycolic acid develop cosmetovigilance to assess the frequency of risk linked to the use of products based on glyoxylic and glycolic acids, and to establish a profile of patients most at risk.