What age should you read It by Stephen King i have read some of his other books such as the stand misery cujo the shining the green mile and others?

I read It when I was 10 and it scared the out of me, I had nightmares for months. I'd already seen the TV miniseries but that didn't bother me at all, the book was WAY scarier. I read other Stephen King books around that age but none affected me quite as much as It. I have an 8 year old niece now and if she expressed an interest in reading It (or any adult Horror novel for that matter) I'd strongly advise my sister not to let her until she's at least 14, not just because they're scary, some of the sexual references in those books are very inappropriate for kids.