This is a review of Warfarin's interaction with many herbal substances: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3976951/ And this research mentions the interaction of Warfarin with Anise: https://pubmed.ncbi.nlm.nih.gov/10902065/ Do not rely on the Drug Interactions feature on Medscape.com or Drug.com in knowing the interactions of natural substances with Warfarin because they may not mention the interaction at all, as in the case of Anise, nor even with the active substances in it. ********************************* Dr. Eyad Abdul Hafez Qunaibi PhD in Pharmacology from the University of Houston, USA, ranking first. Practiced doctoral research at the Texas Medical Center. Participant in two patents in the field of wound healing and a number of therapeutic researches published in international journals. Author of the book PharMedTerm for pharmaceutical medical terminology. https://scholar.google.com/citations?user=T-8FE8sAAAAJ&hl=ar