What is the best treatment for teens who self-harm, more specifically cutting?

Self-harm: Habitual self-harm can be one of features of borderline personality disorder where there is identity diffusion & the act is resorted to in attempt to enlist feeling of temporary relief of discomfort that results from painful traumatic memories. Consult a therapist who specializes with dialectical behavior therapy. Also, treating underlying mood disorder helps.

Cutting: Teens are at higher risk for drug use and cutting, as well as other risky behaviors. This kind of acting out is done as a way of communicating what are often very complex feelings about themselves, their world, their future, and in my opinion, DEEPLY conflicted relationships with people in positions of authority.