The book has been challenged for content dealing with sexually explicit situations. Two teachers at Depew High School near Buffalo, New York, used the book for eleventh grade instruction. A letter was sent to parents advising them that the book contained controversial content. An alternate reading selection was available for those opting out, and a small percentage of parents chose this option. Nevertheless, the book was challenged on the grounds that it is "pornographic" and "disgusting". One parent even went as far as refusing to read the book himself, reportedly saying that "One does not need to have cancer to diagnose cancer". The book was ultimately kept in the curriculum by the school board after a unanimous school board vote. Green defended his book on his blog.
In March 2012, The Knoxville Journal in Knoxville, Tennessee, reported that a parent of a 15-year-old Karns High School student objected to the book's placement on the Honors and Advanced Placement classes' required reading lists for Knox County High Schools on the grounds that its sex scene and its use of profanity rendered it pornography.
The main characters in the story are teenagers who also drink, smoke, and use explicit language. Green has publicly defended his work. "Some people say, 'You wrote a dirty, dirty book.' But there are very old-fashioned values and even a lot of religion in it," Green said. "There are some adults who think that the only kind of ethics that matter are sexual ethics. So they miss everything else that is going on in the book." Green also said, "The book has never been marketed to 12-year-olds. Never. It is packaged like an adult book; it doesn't even say it's published by a kids' book imprint on the cover, and it's never shelved in the children's section of bookstores."