In a press release, the National Academy of Medicine warns of the risks of chemical hair straightening, called Brazilian straightening, for which cases of acute renal failure have been reported.
- Glyoxylic acid, a substance used in Brazilian hair straightening chemicals, is risky for your health.
- Oxalic acid crystals formed in the renal tubules of a 26-year-old woman who had undergone this hair straightening method.
- The National Academy of Medicine is warning and calling for better information for health professionals, hair salons and users.
Chemical hair straightening, or Brazilian hair straightening, is risky for health, the National Academy of Medicine indicates in a communicated published this Thursday, June 6. It is the substance used for hair straightening, glyoxylic acid, which is targeted.
Cases of acute renal failure after hair straightening
The National Academy of Medicine warns fans of Brazilian straightening by citing two recent studies. In the first, published in 2023 in the journal American journal of kidney diseasesthe researchers analyzed 26 cases of patients who suffered acute renal failure following a hair straightening procedure. They noted that two of them had recurrent episodes of acute renal failure after having multiple Brazilian hair straightening procedures.
In the second study, published in March 2024 in the journal The New England Journal of Medicinescientists report the case of a 26-year-old woman who suffered acute kidney failure three times after having Brazilian hair straightening. This patient had never had any health problems before.
But why such a link between Brazilian straightening and kidney failure? People who use this straightening technique are exposed to glyoxylic acid, either through skin contact, eye contact or inhalation. Scientists indicate that, in the case of this 26-year-old woman, oxalic acid crystals formed in the renal tubules, “induced by acid absorbed by the scalp and skin during straightening.”
The product the patient used for her Brazilian blowout contained 10 percent glyoxylic acid. That’s far less than the 30 percent maximum considered safe by the “Cosmetic Ingredient Review” for short-term use. This means that people who use these products are at risk, even with doses much lower than those that are authorized, at the most, for this type of product.
The scientists confirmed their observation by applying a skin-smoothing product containing 10 percent glyoxylic acid to the skin of mice. Within 24 hours, the rodents had calcium oxalate crystals in their urine, which was not the case in the control group of mice.
“Glycolic acid, metabolized into glyoxylic acid, is also widely used for facial peels at concentrations most often close to 30%, warns the National Academy of Medicine. (…) An observation of acute renal failure in a patient who had had a kidney transplant for 4 years was described after 5 facial peels with glycolic acid (at a concentration between 40 and 70%). Renal biopsy revealed the presence of oxalate crystals.”
Brazilian Smoothing: 4 Recommendations from the National Academy of Medicine
Faced with these risks, the National Academy of Medicine issues several recommendations:
- Inform health professionals, hair salons and stores selling cosmetic products based on these acids about the risks.
- Inform users about the risks and signs of acute renal failure (nausea, acute abdominal pain, vomiting).
- Do not perform hair straightening or peeling on damaged scalp or facial skin, as this 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.
While there is a risk associated with using these hair products, about 50% of severe kidney failure is due to diabetes or high blood pressure, according to National Institute of Health and Medical Research (Inserm).