Thailand’s Minister of Public Health recently promulgated the Ministerial Notification Re: Category 5 Narcotics Which Are Not Cannabis or Hemp Extract and Whose Consumption is Permitted for Treatment of Disease or for Research Purposes (2024). The notification took effect on April 23, 2024. The substances whose regulatory controls are affected by this new notification are psilocybin mushroom (Psilocybe cubensis (Earle) Singer), opium poppy (Papaver somniferum L. and Papaver bracteatum Lindl.), and other plants in these genera from which opium, opium alkaloids, psilocybin, or psilocin may be derived. As a result of this notification, these substances are now classified as category 5 narcotics that can be applied in medical treatment. Without the implementation of this notification, patients could not access newly developed medicines containing these substances, as Thailand’s Narcotic Code prohibits the possession and use of category 5 narcotics. Nonetheless, this does not mean that psilocybin mushrooms and opium can be used without any conditions. There is still a long process to go through before these substances can be used in medical treatment or clinical studies. Under the new notification, the FDA must first approve any medicinal drug formulation containing any of the above substances, and subsequently, the production must be approved for medical use or research purposes. The importation of medicinal drug formulations containing psilocybin mushrooms or opium is not allowed. This seemingly small regulatory change addresses the previous legal obstacle to the research and development of such medicines. According to the previous regulation, a physician or researcher could apply to the Thai FDA for a license to produce or possess medicines containing the aforementioned narcotics. However, production and consumption are considered different activities, and consuming a narcotic-containing medicine, even if it was produced under a valid license, is prohibited by the Narcotics Code and is punishable by imprisonment,