Epigenetic mechanisms allow for transgenerational memory of an ancestor's environment and can affect the gene expression, physiology and phenotype of that ancestor's descendants, independent of DNA sequence alteration. Among many model organisms, Caenorhabditis elegans has been instrumental in studies of transgenerational inheritance, most of which have focused on the effects of external stressors of the parent worm on the life span and stress resistance of future generations. In this work, we used Nile red staining of accumulated lipids in C. elegans to investigate the transgenerational effect of two benzylisoquinoline alkaloids, namely, berberine and sanguinarine. Our results showed that a reduction in Nile red fluorescence can be propagated to subsequent worm generations. Using mutant worms, we found that the transgenerational effect requires the ASH‐2 component of the histone H3K4me3 complex and the HRDE‐1 worm Argonaute protein. Ash‐2 is also required for transgenerational inheritance of the xenobiotic response in the worm. Our study offers new insights into transmissible drug effects across multiple generations and suggests the importance of such analyses in the drug development process. Using Nile red staining of accumulated lipid, we investigate the transgenerational effect of two benzylisoquinoline alkaloids, namely, berberine and sanguinarine in C. elegans. Our results showed that a reduction in Nile red fluorescence can be propagated to subsequent worm generations. This transgenerational effect also requires the ASH‐2 component of the histone H3K4me3 complex and the HRDE‐1 worm Argonaute protein. [ABSTRACT FROM AUTHOR]