French health authorities reiterated on Thursday, January 23, their recommendation not to use hair straightening products containing glyoxylic acid. The cause is a confirmed risk of acute renal failure. A control body urges the authorities to seize the European Union to explore imposing restrictions or potentially banning this substance in cosmetics.
Hair straightening products containing glyoxylic acid are facing growing scrutiny from the French Agency for Food, Environmental, and Occupational Health Safety (ANSES).
In mid-October, the Agency advised hair salons and individuals not to use hair straightening products containing glyoxylic acid, and advised businesses not to sell them.
At that time, ANSES explained it was a precautionary measure while awaiting the conclusions of an expert report. The action was prompted by reports of severe adverse reactions in women who had been exposed to these products during hair straightening procedures in salons.
“Very highly probable” link with glyoxylic acid
In an opinion dated 21 January [1], based on scientific studies, the Agency considers it “highly probable” that glyoxylic acid is the cause of these cases of acute renal failure – by passing into the bloodstream via the scalp, it transforms into calcium oxalate crystals, damaging the kidney.
ANSES therefore urges that a risk assessment be carried out at European level, “to limit or even prohibit the use of this substance”, the content of which can be up to 25% in hair care products.
The agency also calls for identifying other products that could “break down into glyoxylic acid” and “potentially release formaldehyde, a carcinogenic substance, during the hair-heating phase.”
After this opinion is communicated by the French authorities, the European Commission will need to consult its Scientific Committee on Consumer Safety (SCCS), the sole body authorized to assess the necessity of regulating a substance under European cosmetics regulations.
A substance banned in Israel
To date, glyoxylic acid has never been assessed at EU level, its use is neither regulated nor limited.
However, hair straightening products containing glyoxylic acid have been banned since 2022 in Israel – “but not those containing derivatives”, said ANSES.
In Israel, from 2019 to 2022, 26 cases of severe acute renal failure —characterized by symptoms such as abdominal and lower back pain, nausea, vomiting, and skin rashes—were linked to the use of hair straightening products and attributed to glyoxylic acid.
Similar to cases in France, patients’ kidney function returned to normal following rehydration.
Safety review
Since ANSES’s expertise only focused on glyoxylic acid, it did not identify specific hair straightening products that should be avoided. However, the Agency “urges marketers to review the safety of products containing glyoxylic acid and the relevancy of precautions for use contributing to safe use.”
Glyoxylic acid is also used in the composition of cleaning and furnishing products (it inhibits corrosion) or tanning products.
