The actress, who plays Sansa Stark on the show, admits things got a little filthy on set once season five began, because the stars were encouraged not to wash.
"For the first few seasons I was allowed to wash my hair because I was an aristocratic young girl," the young Brit tells InStyle, "but toward season five they started asking me to not wash my hair and it was really disgusting.
"Now I wear a wig, so I can wash my hair whenever I want, which is nice. But, yes, for a couple of years I was living with pretty greasy hair."
Turner recently revealed she had taken to wearing wigs for the show because constant dying was ruining her locks.
"A few years ago I was trying to go back from red to blonde, and it destroyed my hair to the point that I had to use a wig for 'Game of Thrones'," she told Glamour. "They wouldn't let me dye it back red or my hair would've fallen out."
The 22-year-old is a natural blonde but her character on the show has a signature mane of red hair, so she has been coloured and teased regularly ever since she joined the drama in 2011.
She has taken to using the Wellaplex No3 Hair Stabilizer by Wella to protect her hair.
"It repairs the bonds in your hair, so that it doesn't just feel strong and healthy, it actually is stronger and healthier afterwards," the Wella ambassador explained. "I use it every week, because with the job I have, it's a lot of dyeing, straightening, curling, and heat damage."