Stroke patients supplements warningInterferes with blood thinning medication
Patients prescribed the blood-thinning drug warfarin are often unaware that also taking popular dietary and herbal supplements may be putting their lives at risk, scientists say.
Warfarin is used to prevent blood clots from forming in patients who have had strokes, heart attacks and other conditions which increase the risk of blood clots.
It is already known that dietary and herbal supplements can reduce the effectiveness of warfarin.
But a survey of 100 patients prescribed the drug found that, of 35 patients combining warfarin with supplements, more than half were unaware of potential dangerous interactions.
The researchers from the Intermountain Medical Centre Heart Institute in Salt Lake City also found that of the 100 most-used supplements, 69 per cent interfere with the effectiveness of warfarin.
"This is an alarming finding," said study author and heart rhythm specialist Dr T. Jared Bunch.
Warfarin and herbal and dietary supplements "compete" in the liver - with the supplements changing the way the drug works - either by intensifying its active ingredients and increasing the risk of bleeding, or by reducing its effectiveness, increasing the risk of stroke, Dr Bunch said.
"We need to do a better job of teaching our patients about the dangers of mixing warfarin with these products. Physicians must be active in asking about supplement use and not place responsibility on patients."
Patients often fail to inform doctors when taking supplements, he added.
"We need to tell our patients that it's acceptable to use herbal and drug supplements, but important for them to tell us so that we can educate them about the benefits, dangers, and potential interactions with their other medications," Dr Bunch said.
The study found that those taking herbal and dietary supplements often experienced worse outcomes, possibly attributable to drug interaction such as reported higher rates of unexplained bleeding and a greater need for blood transfusions.
The findings were presented at the American Health Association's annual scientific meeting in Chicago.
This article was published on Tue 16 November 2010
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