Dangerous Food Medication Interactions

You’ve probably heard the warnings not to drink grapefruit juice with cholesterol medication. However, that isn’t the only combination of food and drugs to avoid. Grapefruit juice can interact with numerous other medications, both prescription and over-the-counter. And many other foods commonly interact with drugs, too.
Grapefruit Juice
One way grapefruit interacts is by increasing the absorption of certain drugs — as is the case with some, but not all, cholesterol-lowering statins. MedinePlus recommends avoiding grapefruit juice if you are taking statins.
Grapefruit juice can also cause the body to metabolize drugs abnormally, resulting in lower or higher than normal blood levels of the drug. Many medications are affected in this way, including antihistamines, blood pressure drugs, thyroid replacement drugs, birth control, stomach acid-blocking drugs, and the cough suppressant dextromethorphan. It’s best to limit intake of grapefruit juice to 16 ounces per day when taking these medications.
Green Leafy Vegetables
Blood-thinning drugs such as Coumadin® (warfarin) interfere with vitamin K-dependent clotting factors. Eating too many green leafy vegetables, which are high in vitamin K, can decrease the ability of blood-thinners to prevent clotting. But you don’t have to give up greens altogether. Problems arise from sudden increasing or decreasing intake. So eat your greens in consistent amounts and you will avoid this issue.
Natural Black Licorice (Glycyrrhiza)
Glycyrrhiza — a natural ingredient used to make black licorice — can deplete the body of potassium while causing an increased retention of sodium. When the body is depleted of potassium, the activity of digoxin, a medication used to treat heart failure, can be greatly enhanced, resulting in the heart not beating properly.
Glycyrrhiza can also decrease the effectiveness of high blood pressure medicines. And people taking Coumadin® (warfarin) should beware that glycyrrhiza can break down the drug, resulting in an increase in the body’s clotting mechanism.
Artificially-flavored black licorice doesn’t contain glycyrrhiza and is not of concern.
Salt Substitutes
Consumers taking digoxin for heart failure or ACE inhibitors for high blood pressure should be careful with salt substitutes, which most often replace sodium with potassium. With an increased consumption of potassium, the effectiveness of digoxin can be decreased, resulting in heart failure. And those taking ACE inhibitors might see a significant increase in blood potassium levels, as these drugs are known to increase potassium.
When receiving a prescription for a new medication or taking a new over-the-counter drug, always read drug warning labels and ask their pharmacist about which foods or other drugs they should avoid or be concerned about taking.