BACKGROUND: Ayahausca is an ethnobotanical drink of South America and the compound dimethyltryptamine (DMT) is primarily responsible for the hallucinogenic effects. DMT has a short half-life and its detection in urinary drug screens is challenging. We investigate a simple alternate approach to detect ayahuasca consumption by relying on other constituents of the drink, the β-carboline harmala alkaloids. METHODS: Three commercially sourced harmala alkaloids were characterized and added to a non-targeted high-resolution mass spectrometry urine drug screening method. All analyses were performed on a Waters Xevo G2-XS LC-QTof, in positive electrospray ionization mode. The mass detector was operated in MSE mode and data processed with UNIFI™ software. A urine specimen from a patient suspected to have consumed ayahuasca was analyzed by a non-targeted drug screen. RESULTS: The harmala alkaloids: harmine, harmaline and tetrohydroharmaline (THH) were characterized and their detection data added to the toxicology screening library. Harmaline and THH were detected in the patient's urine specimen. CONCLUSION: The inclusion of the harmala alkaloids into the drug screen method library may enable the detection of ayahuasca use in patients that undergo non-targeted drug screen.