LINDA Blair’s portrayal of the demonically possessed Regan in the 1973 horror classic, “The Exorcist,” was a head-spinning experience in more ways than one.

On the eve of the rerelease of the hysteria-inducing box-office smash, the petite 41-year-old actress has cause to revisit the nightmare that followed the film’s controversial release.

“It changed my life,” says Blair, who these days devotes much of her time to developing TV projects and promoting alternative health therapies and animal rights.

It wasn’t the much-rumored “curse” that supposedly plagued the shoot, but the movie’s post-release fallout that gave the then-14-year-old a devil of a time.

“When the film came out, I guess there were many people that connected with it in some way, and they felt that the connection was to me, and that they needed to be near me,” she says.

“No one could prepare anybody for this type of instant, international fame. I don’t know what the people wanted from me. It was like being one of The Beatles. It was frightening.”

Police were posted outside Blair’s Connecticut home for six months, to keep the cranks at bay, and her life began to be scrutinized microscopically. There was speculation she was mentally disturbed, and the press had a field day with her 1977 drug bust.

“They dragged my name through the mud, and I think it’s taken many, many years to clear that,” she says. “I always say, you live your life, do the best you can, and some day your reputation will catch up with you.

“So if I was that person that people accused me of [being], then why am I like this today? Why do I go out and put my life and my career on the line for animals, for people?

“I think I had to live my life in order for it to come to this point. Because I am a nice person.”

William Peter Blatty, who wrote “The Exorcist” screenplay from his best-selling novel and also produced the film, scoffs at the notion Blair could have been scarred by her experience filming scenes in which she spewed invective and pea-green liquid, and jabbed a crucifix into herself.

“We all tiptoed around her,” he says. “But it was absolutely needless – she giggled after every take. It was all a big ride through a fun house.”

Blatty, who is currently adapting his short story “Elsewhere” for the screen, lobbied hard from the start to include the 11 minutes of footage that was cut from the original film. It’s back in the rerelease.

“I’m thrilled it’s coming out now,” he says. “I’m glad I lost the argument for 27 years, and it waited until now.

“I think this is the perfect time for this film, especially in this more spiritual form, to be presented to the public. I think there is a desperate hunger for transcendence, for faith, for belief in an absolute.”