People taking digoxin should read product labels carefully for licorice plant ingredients. Bisacodyl , a laxative similar in action to senna, given with digoxin decreased serum digoxin levels in healthy volunteers compared with digoxin alone. In patients taking digoxin, laxative use was also associated with decreased digoxin levels. In addition, concern has been expressed that overuse or misuse of senna may deplete potassium levels and increase both digoxin activity and risk of toxicity. However, overuse of senna could also decrease digoxin activity because, as noted, laxatives can decrease the levels of the drug.
People taking digoxin require regular monitoring of serum digoxin levels.
In one report, addition of a product identified as Siberian ginseng to stable, therapeutic digoxin treatment was associated with dangerously high serum digoxin levels. The patient never experienced symptoms of digoxin toxicity. Laboratory analysis found the product was free of digoxin-like compounds but the contents were not further identified. This report may reflect an interaction of eleuthero with the laboratory test to cause a falsely elevated reading, rather than actually increasing digoxin levels. One uncontrolled study has suggested that St. John's wort may reduce blood levels of digoxin.