Everything you eat has the potential to interact with prescription medications. Patients should be advised that non-prescription drugs, including food supplements and herbs, are not regulated so that the precise composition of the substances are often unknown. Pharmacists are careful to inform patients when medications can interact adversely when combined with other medications and foods. However, patients often do not realize that the use of some prescription medications with herbal supplements can have unwanted side-effects. It can form a complex, or chelate, with the active component of the medication, making the medication ineffective.
Food can also enhance the effect of a medication and make it stronger.
Medications can increase the body's need for the nutrient. They can cause excessive excretion of the nutrient. Since many people take herbal supplements without their physician's knowledge, the potential for dangerous interactions is greatly increased. Digoxin, used to treat congestive heart failure, when combined with senna or Siberian ginseng can enhance the drug's effect, leading to possible irregular heartbeat. Diuretic herbs, or those that promote increased urination such as St. John's wort and uva ursi, can cause excessive potassium loss and potential toxicity when combined with digoxin.