Estelle, 19, told Le Parisien, that the reaction happened two weeks ago when she wanted to transform herself from a blonde into a brunette with a para-phenylenediamine (PPD)-based dye.
But in the hours and days after applying the hair dye, her scalp began to itch and then her head started to swell.
The swelling came after a pharmacist told her to use antihistamines and cream to stop the itching.
She woke up the following morning to find that her head circumference had grown to 25 inches (63 centimeters) — the average is average 22 inches (56 centimeters).
“My forehead had doubled in volume,” Estelle, who has not revealed her last name, told Le Parisien. “My head was like a light bulb.”
Upon seeing how large Estelle’s head was, her mother took her to the emergency room where doctors said reactions to PPD are fairly common, though usually not as severe as Estelle’s.
According to Newsweek, PPD is found in 90% of hair dyes, but the concentration of the chemical has been regulated since 2013.
Doctors gave Estelle and adrenaline shot and watched her overnight for observation to make sure the swelling went down.
For Estelle, the experience was terrifying.
“Before arriving at the hospital, you just don’t know how long it will take for you to suffocate, if you have the time to get to the hospital or not,” she told Le Parisien.
According to the National Health Service in the UK, hair dyes with PPD in them are safe as long as safety instructions are followed.
The organization suggests performing a patch test to make sure there are no severe reactions before using it on hair.