Dietary supplements can cause harmful reactions with prescription medicines

More than one of every five people who take prescription drugs also use dietary supplements, like ginseng and gingko, without telling their doctors. Such combinations may lead to harmful results, such as interfering with the action of prescription medications taken for conditions ranging from insomnia to heart disease, cancer, and arthritis.

“Amid increasing numbers of reports describing interactions between prescription drugs and nonvitamin dietary supplements, concern has grown regarding the troublesome possibility of adverse effects,” notes Paula Gardiner, a research fellow at Harvard Medical School. She and her colleagues at Harvard-affiliated Beth Israel-Deaconess Medical Center in Boston recently completed a study to determine how many and which people in the United States mix the two.

Using results from the 2002 National Health Interview Survey, the latest available, they conclude that 21 percent of the estimated 135 million adults in this country who took prescription drugs also used nonvitamin supplements without discussing the combinations with their doctors. This total of 28 million people was up from an estimated 15 million in 1997. Now that the U.S. population has reached 300 million, the number in 2006 is probably higher still.

The most commonly used supplements were echinacea (for colds and flu), ginseng (to increase stamina and energy), gingko (for memory enhancement), garlic (to lower cholesterol and blood pressure), glucosamine chondroitin (for arthritis), and St. John’s wort (to treat mild depression).

The highest users were those with chronic but not life-threatening conditions such as menopause, stomach and intestinal woes, headaches, and insomnia. Lowest users, fortunately, included those with life-threatening conditions such as heart disease, stroke, and diabetes.