Namely
In an article published in the New England Journal of Medicine in March 2024, French researchers warn that the use of glyoxylic acid in hair straightening products is associated with a risk of acute renal failure through the accumulation of calcium oxalate crystals in the kidneys.
The researchers state that "Given the potential nephrotoxicity of topical glyoxylic acid, products containing this compound should be avoided and, in our opinion, withdrawn from the market".
For these reasons, this ingredient is displayed in red on INCI Beauty.