This review highlights heterogeneity within multiplicity-spectrum experiences, emphasizing the need for person-centred, individualized understanding, separate from mental health conceptualizations. Therefore, training in person-centred individualized care to promote self-concept clarity is needed across health, education and social care. This systematic review is the first to synthesize voices of people with lived experience across the multiplicity spectrum, demonstrating how qualitative research can contribute to advancing our understanding of this complex phenomena with the community, acknowledging reciprocal psychosocial impacts of multiplicity and providing valuable recommendations for services.