Warning: Drug Interactions with Common Foods Can Be Deadly

Did you know that foods you eat every day can interact with medications and trigger dangerous reactions that can lead to permanent disability or even death? Even more frightening is that some foods rated among the healthiest can actually be among the deadliest.

How can we know which foods and drugs to watch out for? And how can we protect ourselves from food/drug catastrophes?

Grapefruit tops the list of foods that cause problems. Although many people know that it shouldn’t be taken with blood thinners, it reacts with dozens of medications. “It’s not just heart drugs,” says David Bailey, Ph.D., clinical professor of pharmacology at Canada’s University of Western Ontario. “At least 66 medications are known to interact with grapefruit juice, including some anticancer drugs,” Bailey tells Newsmax Health.

Food and drug interactions cause two main problems. First, some foods block the body’s ability to absorb medications, lowering their effectiveness, and, in some cases, causing them to be useless.

“Patients believe the drug isn’t working when it’s a food they’re eating that’s blocking its absorption,” Bailey explains.

Second, other foods increase a drug’s absorption, which can lead to an overdose. For example, grapefruit juice can boost the strength of some drugs 10 times. With statin drugs, it causes problems by inhibiting the action of enzymes that break down statins in the body.

How much of a particular food is too much? There’s no easy answer. “The physical makeup of each patient determines who’s going to have problems, and there’s a great variability among individuals,” says Bailey.

“One person may take a food/drug combination and be fine, and the next one may have a serious reaction.” he says. “We can’t predict which patient will have a problem.”

Age, weight, and gender are variables as well as individual body chemistry. Since older adults tend to take more drugs, they are at greater risk for food/drug interactions.

Food/drug interactions can appear suddenly. Patients can take a drug for months or years with no problem and suddenly have a life-threatening reaction.

“They’ll end up in the emergency room, and the question is, ‘What happened?’” Bailey says. “Unless the doctors and nurses ask them what in their diets has changed, they’ll never know. And they never think to ask the question.” Just increasing the amount of a particular food a patient may have eaten for years with no problem could trigger a reaction.

How many food/drug interactions occur each year? No one knows, says Bailey. “Unless individuals are aware of the possibility, the question would not likely be asked.” In addition, many food/drug interactions have only recently been discovered, and doctors are often unaware of the latest findings.

Fortunately, most reactions are not life-threatening. However, most are probably neither recognized nor reported by either patient or doctor.

The most common food/drug interactions include:

• Grapefruit juice. Drinking grapefruit juice within hours of taking a category of heart drugs called calcium channel blockers (Procardia) can have deadly consequences. Combining grapefruit juice with cholesterol-lowering statins or cyclosporine (a drug used for transplants) may increase their effects. Mixing it with antihistamines, even over-the-counter versions, can cause serious heart difficulties. Orange juice can have similar effects, although usually to a lesser degree.

• Milk and yogurt. Calcium in milk and other dairy products blocks the absorption of antibiotics (including tetracyclines) and decreases effectiveness up to 80 percent. Other problem meds include thyroid hormones, iron supplements, and penicillamine, a drug used to remove excess copper from the body. Calcium can also interfere with the absorption of alendronate (Fosamax), an osteoporosis medication.

• Spinach. Eating large amounts of leafy green vegetables such as spinach, kale, and mustard greens, which are rich in vitamin K, blocks the blood-thinning effects of warfarin. Liver, which is also high in vitamin K, also increases the risk of bleeding.

• Cranberry juice. Cranberry juice can increase the effects of warfarin (to cause uncontrollable bleeding) and antidepressants, such as Prozac. Both cranberry and pomegranate juices can also affect the metabolism of statins.

• Licorice. Licorice can increase the risk of toxicity for those taking digoxin, which is used to treat abnormal heart rhythms and congestive heart failure. It can also reduce the effectiveness of diuretics and blood pressure drugs.

• Aged cheese. Tucking into a plate of cheese after taking MAO inhibitors that treat depression and Parkinson’s disease could send your blood pressure skyrocketing. Tyramine, a compound found in aged cheeses as well as smoked meats, aged sausages, and red wine, is the culprit.

• Chocolate. Satisfying your chocolate craving could increase the effects of stimulant drugs used to treat ADHD, such as Ritalin, and increase their effect.

• Grilled meat. The carbon compounds formed when grilling prevent theophylline, a medication used to prevent and treat asthma, COPD, and other lung diseases, from working. Charbroiled meats can also decrease the effectiveness of blood-thinning drugs such as warfarin. The caffeine in coffee can also interfere with theophylline.

• Fiber. Although fiber is necessary for a healthy diet, go easy on high-fiber foods, such as peas, whole wheat pasta, and bran if you’re taking certain medications. Fiber can slow the absorption of many drugs, including diabetes medication (metformin), cholesterol-lowering statins, some antibiotics (penicillin), and digoxin, which is used to control irregular heartbeats.

• Alcohol. Mixing alcohol (all types, including wine) with antidepressants, sedatives, antihistamines, and some antibiotics can all be potentially deadly. One study found that the hops in beer reduced the live-saving effects of the cancer drug Tamoxifen.