Introduction: Vervain is a perenial herb from Europe with scientific name Verbena officinalis, also known as Holy Herb or Simpler’s Joy. Vervain Adverse Reactions and Interactions: Verbena officinalis may decrease the effect of warfarin (Coumadin) therapy since it contains vitamin K. Assessment and Plan: Verbena officinalis may decrease the effect of warfarin (Coumadin) Read More »