APA article notes that the DSM-5 considered including pornography addiction, but decided there was not enough evidence.
Weir, Kirsten. "Is Pornography Addictive?" American Psychology Association. Monitor on Psychology 45(4): 46
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When the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) was being drafted, experts considered a proposed diagnostic addiction called hypersexual disorder, which also included a pornography subtype. But in the end, reviewers determined that there wasn't enough evidence to include hypersexual disorder or its subtypes in the 2013 edition.
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