Giving supplement such as herbs, vitamins, and other natural health products to children taking Warfarin for congenital heart defects could increase their risk of clots, bleeding, and other complications, nurse practitioner Mary Bauman and Dr. Patti Massicotte told the 2008 Canadian Cardiovascular Congress, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.
"We just assume these products are safe because they are 'natural' and don't require a prescription," says Heart and Stroke Foundation-funded researcher Dr. Massicotte. "The problem is that the anticoagulant action of Warfarin is unpredictable on its own, so adding dietary supplements to that can be a challenge. Sometimes that product is the straw that breaks the camel's back and could push children into high risk situations."
She says that many marketed supplements can cause changes in the blood and shouldn't be taken with Warfarin, but there is little research on drug interactions with these kinds of products. "There is no standardization of the active ingredient per capsule or tablet between companies and it is this variation - especially in combination products - that provides the greatest challenge," she says.
Some of the most common natural health products taken by the children in the study included chamomile, lemon, fennel, and green tea. Multivitamins and minerals were also high on the list, which, Dr. Massicotte warns, can be a problem if they contain vitamin K - a vitamin that enhances clotting and could make Warfarin less effective.
Ms. Bauman, the creator of the Pediatric Outpatient Anticoagulation Clinic in Edmonton, Alberta has been working with Dr. Massicotte to see how many children are taking natural health products. They looked at 67 questionnaires which surveyed children taking Warfarin.
Warfarin is an anticoagulant - also often called a blood thinner - that helps prevent blood clots from forming in the body. Blood thinners help reduce risk for heart attack, stroke, and blockages in the arteries and veins.
They found that 37 per cent of children with heart problems were taking some kind of dietary supplement and 22 per cent of their parents and 10 per cent of their healthy siblings were taking them as well. Yet, few parents informed their doctors about their children's use of natural health products - which can be dangerous for the child since an interaction could occur with their medication.