Avoiding a Prescription for Disaster

December 2001

As our population ages, more and more people take medications and embrace “alternative” ways to combat health concerns. Dietary supplements, herbs and specialty foods are becoming increasingly mainstream home-health options with a larger segment of the American population. However, it can be confusing and frustrating for consumers to try to fit the pieces of their “personal health-care puzzle” together, especially considering potential negative interactions between food, herbs and medications.

Mixing food and medicine
The following are some common drug-food interactions to be aware of:
Antibiotics. Some antibiotics (including penicillin and erythromycin) should not be taken with acidic foods (such as citrus, coffee or tomato products) because acid interferes with absorption. Quinolones and tetracyclines may interact with dairy products, antacids, calcium and iron supplements, and magnesium-containing laxatives, resulting in decreased absorption. Avoid taking quinolones with caffeine-containing products, which may lead to excitability and nervousness.

Anticoagulants. Anticoagulants, such as warfarin, help prevent blood-clots. Vitamin K produces blood-clotting substances, so its dietary level should remain relatively constant. Onions and garlic may also increase the drug’s effects, leading to bleeding. High vitamin E doses (400 IU or more) or ginkgo biloba may prolong clotting time and increase bleeding risk. Ginseng also may decrease the efficacy of certain anticoagulants.

Antidepressants. People taking antidepressants, such as paroxetine, sertraline and fluoxetine, should avoid alcohol, which can increase drowsiness and worsen symptoms. St. John’s wort and other herbs could also interact with these, producing various adverse side effects.
Antihistamines. Because some over-the-counter or prescription antihistamines increase drowsiness and slow mental performance, they should not be mixed with alcohol. Grapefruit juice may change absorption.

Aspirin. Combining aspirin with alcohol might lead to stomach irritation and higher-than-expected blood-alcohol levels. Because aspirin serves as a blood thinner, taking it with excessive vitamin E or ginkgo biloba may increase the risk of excessive bleeding.

Blood pressure medications. In general, avoid excess sodium with medications for high blood pressure. Some medications may cause the body to retain potassium, while others make the body lose it. If taking ACE inhibitors, avoid excess potassium.

Calcium channel blockers. Grapefruit juice should be avoided two hours before and after taking these medications for best absorption, as it can inhibit enzymes in the intestine that aid absorption. This results in increased blood levels of the medication.

Digitalis. It’s important to avoid bran, oatmeal and other high-fiber foods, which may interfere with absorption when taking this medication. Because this drug also may deplete potassium stores, potassium-rich foods should be added to the diet. Natural licorice in candy, smokeless tobacco products, cough drops and sweetening agents should be avoided, as it can accentuate potassium losses.

Diuretics. There are different types of diuretics — which can help eliminate water, sodium and chloride from the body — that may vary in their interactions with foods and individual nutrients. Some diuretics (furosemide or Lasix®) cause the loss of potassium, calcium and magnesium. Natural licorice should be avoided with these medications, and added potassium may replace losses. Other diuretics (such as Aldactone® or Midamor®) are known as “potassium sparing” and block potassium excretion, so excessive potassium can lead to a possible irregular heartbeat.

MAO inhibitors. People taking these types of antidepressants, such as phenelzine or tranylcypromine, must be very cautious about interactions. Alcoholic beverages and non-alcoholic beer and red-wine products should be avoided. Consuming foods containing tyramine while taking MAO inhibitors might result in a potentially fatal blood-pressure increase. These include broad beans, yeast concentrates, smoked or pickled fish, and aged cheeses, such as Stilton, Roquefort, Camembert, Brie, Cheddar, Swiss, brick and Parmesan. Other sources: bananas, avocados, soy sauce and processed meats.

Herb concerns
In a recent review entitled “Herbal Medicines and Perioperative Care,” published in July 11, 2001 issue of The Journal of the American Medical Association, researchers selected studies, case reports and reviews monitoring the safety and pharmacology of eight commonly used herbs. They hypothesized that the widespread use of herbal medications by patients before surgery could have a potentially negative impact on perioperative patient care.

The researchers concluded that echinacea, ephedra, garlic, ginkgo biloba, ginseng, kava, St. John’s wort and valerian may pose a concern during the perioperative period. Some common concerns include bleeding from garlic, ginkgo biloba and ginseng; cardiovascular instability from ephedra; and hypoglycemia from ginseng. Pharmacodynamic herb/drug interactions included potentiation of the sedative effect of anesthetics by kava and valerian. In addition, St. John’s wort was found to increase the metabolism of many drugs used in the perioperative period.

In today’s health-conscious world, consumers are encouraged to take charge of their health. Being aware of potential interactions between medications, foods and herbs is an important key for better health.

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