Warfarin–supplement interactions: a systematic review

Introduction: Food supplements, which are concentrated forms of nutrients, play a crucial role in maintaining a balanced diet by providing essential missing nutrients. However, their impact on drug interactions cannot be overlooked. One such drug is warfarin, an anticoagulant with a complex interplay involving various medications, foods, and supplements. Given the significant increase in the use of dietary supplements in recent years, there is a compelling rationale to investigate their interactions with warfarin. This systematic review aims to identify supplements that interact with warfarin, thereby providing insights into potential risks and implications.

Methodology: In order to address the research question “What potential drug interactions may arise when food supplements are taken concomitantly with warfarin?”, a PRISMA 2020 systematic review was conducted. To accomplish a comprehensive understanding of the issue at hand, several databases were consulted. In order to fulfill the search platforms' requirements, the terms "interactions," "warfarin," and "supplements" were combined in multiple ways. The inclusion criteria took into account original, randomized or non-randomized studies and case studies that mention a supplement used concomitantly with warfarin. An artificial intelligence-based tool was used to evaluate the studies' quality. The obtained results were summarized in a table format, detailing the supplement used and the how the interaction occurs.

Results: A search of the literature yielded 968 articles, of which 14 were selected for review. These articles met the specified criteria, namely the use of a dietary supplement concomitantly with warfarin. Of these, 11 indicated a potential interaction, while 3 articles suggested that no interaction occurred.

Conclusions: This work clarified the interactions between supplements and warfarin, emphasizing supplements such as dong quai, milk thistle, and American ginseng, which alter the mechanism of action of the drug. Furthermore, it is imperative for patients to seek counsel from healthcare professionals before modifying their dietary regimen.