Research on psychedelic-assisted psychotherapy has shown that music affects therapeutic outcomes at a fundamental level. The development of such therapies calls for research on the use of music with consciousness-altering substances, especially in contexts informed by their traditional use. Informed by ethnographic reports, our project answers this call, investigating the phenomenology of listening to icaros (medicine songs) during ayahuasca ceremonies as reported by addiction rehabilitation patients at Perú’s Centro Takiwasi. We found that icaros were therapeutically significant. They elicited experiences of healing by modulating patients’ emotions and the altered state induced by ayahuasca. They helped patients feel safe while guiding them through difficult memories and emotions, and facilitating experiences of healing and learning about their addictions. Thus, similar therapies must carefully consider how they incorporate music in their protocols. We suggest further research to better understand the synergistic, therapeutic effects of music and altered states of consciousness, especially in cross-cultural environments.