Abstract Warfarin, a commonly prescribed anticoagulant, is utilized to prevent thrombotic issues and requires careful dose adjustment due to its narrow therapeutic range. As warfarin is metabolized by essential drug-metabolizing enzymes (DMEs), it is prone to interactions with a wide range of therapeutic agents, including herbal medicines. In June 2022, Thailand became the first country in Asia to remove cannabis plants from its narcotics control list, allowing individuals to cultivate them for personal use. Consequently, this report aimed to examine the interaction between cannabis and warfarin in Thai patients following the legalization of cannabis from 2021 to 2023. These three case reports elucidated the potential for...