'There's danger going from curly hair to straight'

Despite ban, dozens still suffering kidney failure from toxic hair treatments

After two hospitalized within weeks, doctor behind pioneering study on glyoxylic acid says straightening products still entering Israel and seeping into scalps

Consumers should avoid all hair products that contain the chemical glyoxylic acid, a top doctor warned this week, after a 17-year-old girl who underwent a hair-straightening treatment was hospitalized with severe kidney failure at Shaare Zedek Medical Center in Jerusalem, the second such case in Israel in a little over a month.

Prof. Linda Shavit, director of the Adult Nephrology Institute at the hospital, told The Times of Israel that since 2023, there have been at least 38 cases of women and girls who have suffered acute kidney failure after straightening their hair with the chemical. All were hospitalized, and several required dialysis treatments.

“There’s still danger going from curly hair to straight,” she said. “It is a chemical process.”

The teen was admitted in late December after suffering from vomiting, dizziness, and severe headaches following the treatment, and spent several days in the hospital before being released on December 29.

She told Shavit that she wouldn’t “do the treatment again,” especially because “it took her a while to recover,” the doctor relayed.

Sales of products containing glyoxylic acid were banned by the Health Ministry in 2023 following a pioneering study by Shavit and Dr. Alon Benaya, also from Shaare Zedek, that found 26 cases of girls and women aged 14 to 58 with no underlying medical conditions who arrived at emergency departments across the country with severe kidney failure.

The study, which appeared in the American Journal of Kidney Diseases, was the first in the world to document numerous cases of kidney failure following hair straightening treatments.

Since Shavit’s study, health officials in France and other countries have advised against using products containing glyoxylic acid. However, many places have only instituted restrictions or regulations rather than bans, meaning the products can still be purchased online from abroad and shipped into the country.

“I’m sure there are still hair products with glyoxylic acid in Israel,” Shavit said.

Straight from the scalp to the kidneys

Dr. Marwan Abu Sneineh, a nephrology specialist at Rabin Medical Center, said glyoxylic acid is a “good asset for beauty,” but “should not be absorbed or swallowed, and it should not enter the bloodstream.”

The chemical is used in skincare products, but at lower concentrations that are considered safer.

In hair products, glyoxylic acid is used for its ability to temporarily change the bonds in keratin, which affects whether locks are curly, wavy or straight. During the straightening treatment, a hair iron is used, generating high heat to make the hair lie flat. The heat, together with the higher concentration, raises the risk of the chemical’s absorption into the skin.

Sneineh, who participated in Shavit’s research, said that all the women and teenage girls who came to the hospital suffering from acute kidney injury had irritation in the scalp.

“We think that the port of entry was the scalp,” Sneineh said. “Maybe the use of the product was not according to the manufacturer’s instructions. Maybe it stayed on the scalp for too long, or maybe it was heated and then got absorbed into the bloodstream.”

During a straightening treatment, also known as a “Brazilian blow-out,” if the product touches the scalp, which is porous, it will allow glyoxylic acid to enter the bloodstream.

The body then tries to break it down.

“Once it is in the blood, the body converts it to oxalate,” Sneineh said.

Oxalate is a waste chemical that the body usually removes through urine. But if there is too much oxalate, it can form tiny, rough crystals that can quickly cause havoc to the kidneys.

“The oxalate has only one way to go out, through the kidneys,” Sneineh said. “These crystals can deposit in the kidney tubes and block or damage them.”

The patients in Shavit’s study experienced abdominal pain, nausea, vomiting, and scalp rash after using the hair straightening products. The average age was 28, and most had no previous medical problems.

Shavit said that all the patients recovered after hospitalization, with some spending time in intensive care units.

“But if there is further damage to the kidneys, their condition could become chronic,” she said.

Shavit is now conducting further research into whether the women and girls who had kidney failure because of the straightening treatment might have a genetic disposition to kidney disease.

The price of beauty

Shavit said that when applying any straightening product, it is “essential” to maintain a distance of at least 1.5 centimeters (.6 inches) from the scalp.

One of the earliest warning signs that there might be a problem after a hair treatment is nausea and vomiting that might occur suddenly. People should also be aware of changes in urination or pain while urinating. Onset usually occurs within hours.

It is important to seek medical care immediately.

Miro Vaknin, a hair stylist in Nahariya, told The Times of Israel that he only buys products that have been approved by the Health Ministry.

“I don’t use cheap products,” Vakhnin said. “People who buy from the internet or from shady vendors take a risk.”

He also said he is cautious while doing a hair straightening treatment.

Sneineh, who studied in medical school in Ukraine several years ago, said he learned an appropriate saying about pursuing beauty in Russian.

“The phrase is, ‘You need to sacrifice to be beautiful,'” he said. “But I don’t think that any of us should sacrifice.”