The National Association for Poetry Therapy provides this useful definition of poetry therapy:
What is Poetry Therapy?
Poetry therapy is the use of language, symbol, and story in therapeutic, educational, growth, and community-building capacities. It relies upon the use of poems, stories, song lyrics, imagery, and metaphor to facilitate personal growth, healing, and greater self-awareness. Bibliotherapy, narrative, journal writing, metaphor, storytelling, and ritual are all within the realm of poetry therapy.