Outpatient Management of Complicated Polysubstance Use Disorder with Kratom Dominance Using the MATRIX Program: A Case Series from Thailand

Abstract Background Kratom ( Mitragyna speciosa ) was decriminalised in Thailand in August 2021, followed by the Kratom Plant Act 2022. Despite growing accessibility, clinical data on the outpatient management of kratom use disorder with co-occurring psychiatric comorbidities remain scarce. Objective To describe the clinical presentations, treatment approaches, and outcomes of three patients with kratom use disorder managed in an outpatient addiction psychiatry setting. Methods A retrospective case series of three male patients presenting to an outpatient psychiatric clinic between July and November 2023. All received structured biopsychosocial treatment using the MATRIX Intensive Outpatient Program, combined with brief interventions, motivational interviewing, cognitive-behavioural therapy (CBT), and relapse prevention. Pharmacotherapy was individualised according to comorbidity. Results All three patients (ages 19–24) with complex psychiatric comorbidities reported six-month kratom abstinence using the MATRIX Intensive Outpatient Program and individualised pharmacotherapy. Abstinence was based on self-report and clinical evaluations, as standard immunoassay panels do not detect kratom alkaloids and no mitragynine-specific testing was performed. Conclusions A structured outpatient biopsychosocial program, combined with targeted pharmacotherapy, may facilitate kratom abstinence in patients with complex psychiatric comorbidities. Clinicians should remain alert to emerging primary psychiatric disorders that may be masked or precipitated by kratom and polysubstance use.