Certain herbal supplements can create very real risks during surgery. St. John's wort is a perfect example. Patients may take considerably longer to emerge from surgery when they are taking St. John's wort, which poses a risk for airway compromise after extubation in select patients. The standard recommendation is to stop St. John's wort for at least 5 days prior to the procedure. St. John's wort is not known to affect potassium, clotting, or blood pressure to a significant degree.