Objectives: The objective of this study was to assess how often St. John's wort (SJW) is prescribed with medications that may interact dangerously with it.
Design: The study design was a retrospective analysis of nationally representative data from the National Ambulatory Medical Care Survey.
Settings: The study setting was U.S. nonfederal outpatient physician offices.
Subjects: Those prescribed SJW between 1993 and 2010 were the subjects.
Outcome measures: The outcome measures were medications co-prescribed with SJW.
Results: Twenty-eight percent (28%) of SJW visits involved a drug that has potentially dangerous interaction with SJW. These included selective serotonin reuptake inhibitors, benzodiazepines, warfarin, statins, verapamil, digoxin, and oral contraceptives.
Conclusions: SJW is frequently used in potentially dangerous combinations. Physicians should be aware of these common interactions and warn patients appropriately.