Frequency of kratom-related poison center calls before and after kratom legalization in Thailand: current trends

Introduction: Kratom (Mitragyna speciosa) has traditionally been used in Thailand; however, it was illegal. Following decades of prohibition, kratom was removed from Thailand’s list of narcotics on 24 August 2021, effectively legalizing its use. This study aims to describe the frequency, clinical characteristics, and trends of kratom-related poison center calls before and after legalization. Methods: We conducted a retrospective review of data from the Ramathibodi Poison Center covering three 6-month periods: 24th of August, 2020 to 23rd of February, 2021; 24th of February, 2021 to the 23rd of August, 2021; and the 24th of August, 2021 to the 23rd of February, 2022. Patients with confirmed kratom exposure were included. Results: Overall, kratom exposure-related phone calls involved 173 cases: 39, 38, and 96 cases in the 1st, 2nd, and 3rd periods, respectively. The mean and median ages of all patients were 29 years (SD 14.1 years) and 25 years (IQR 19–38 years), respectively. Most cases (84.4%) involved male patients, while most (∼60%) also co-ingested kratom with other substances. Tachycardia (43.4%) was the most common abnormal vital sign, and palpitations (35.8%) were the most common clinical manifestation. We compared the clinical characteristics of cases among the three periods, revealing no significant differences in age, sex, regions, co-ingestion, or clinical effects. The prevalence of acute dystonia decreased significantly after legalization (12.8%, 18.4%, and 6.3%, P = 0.008). However, cases in the 3rd period were admitted (37.5%) significantly more often than those in the previous two periods (15.8%, 10.3%; P = 0.001). Discussion: Kratom-related calls increased by 2.5-fold after legalization, while consultation and hospitalization rates also rose. Most cases involved young males who used kratom with other substances. The types of symptoms reported before and after legalization remained largely consistent, with neurological and cardiovascular effects predominating. However, hospital admissions increased significantly following legalization. Conclusions: Following kratom legalization in Thailand, hospital admissions increased significantly. Continued poison center surveillance and regulatory oversight are essential for monitoring evolving patterns of kratom use and associated harms in the post-legalization era.