Pauley Perrette Pauley Perrette

As one of the stars of the No. 1 show in the world, NCIS' Pauley Perrette is known for her signature look — her signature black hair color, in particular.

However, the actress revealed to Extra that she can no longer use hair dye as she has for the past several years. "I have acquired an allergy to black hair dye, which is something that I wanted to tell people about," she said. "I tweeted about it, and then it was all over the news because people don't know about it and it can be fatal. It's very serious."

TV wigs: Trick or treat?

So how will the naturally blonde Perrette keep her hair so dark? "I have black hair spray in my hair and we're trying to figure it out," she said. "We're trying to figure out an organic thing."

Because nobody wants Abby's goth look to change, right? "I just don't think Abby should be blonde," Perrette said. "Abby's like a cartoon character, she's never changed." 

NCIS' new season premieres on Tuesday, Sept. 23 at 8/7c on CBS.

(Full disclosure: is owned by CBS.)

Watch This Tonight — See why The Knick is our editors' pick: