Doctors warned cancer patients Tuesday about the potential dangers of mixing alternative and herbal medicines with conventional treatments.
Remedies such as cod liver oil and St. John’s Wort may interfere with blood thinning drugs, hormone treatments or chemotherapy.
“Any patient who takes herbal remedies needs to be aware that there can be potential health risks with them. The risk could be related to the remedy itself and any other medicines they are taking,” Dr. Ursula Werneke, of the Homerton Hospital in London, said in an interview.
In a study of 300 cancer patients at London’s Royal Marsden Hospital, Werneke found that more than half took herbal remedies, or supplements, or both.
Eleven percent used more than the recommended dosage and one-third of the patients weren’t sure why they were taking them, according to the research published in the British Journal of Cancer.
Natural, but not necessarily harmless“There is a perception among the public that herbal remedies are harmless because they are herbal or natural. This paper shows a potential for risk,” she added.
Earlier research has shown that garlic and cod liver oil may exaggerate the effects of at least some blood-thinning drugs.
St. John’s Wort, which is used to relieve mild depression, can interfere with hormone treatment, antibiotics and chemotherapy. Echinacea, which affects the immune system, could also hamper some treatments for lymphoma and leukemia.
Werneke advised patients to tell their doctor about any complementary remedies or supplements they are taking and to be aware that herbal medicines might not always be effective.
“Although they are natural, that does not necessarily mean they are harmless,” she added.
Evening primrose oil, gingko biloba, echinacea, selenium, cod liver oil and vitamins were the most popular complementary remedies and supplements taken by people in the study.
Professor Robert Souhami of Britain’s Cancer Research charity said in a statement: “This research is very valuable in that it indicates more work needs to be done to get a clearer picture about how complementary medicines react with conventional drugs."