When Herbs and Prescriptions Clash

From the Spring 2008 issue of StayHealthy Magazine

"Do Not Take Together"

Herbs have become a popular addition to the daily multi-vitamin most Americans take.  Whether it’s ginkgo biloba to boost your brain power and energy or melatonin to help you sleep, it is estimated that 7 our of 10 Americans takes at least one herbal supplement on a regular basis and that less than one third of those individuals tell their doctors of its use.

The phenomenon is causing concern for medical practitioners, who are increasingly aware that the prescription medications they are prescribing for such things as preventing blood clots, heart arrhythmias or Parkinson’s-related tremors can have unwanted side effects when coupled with the use of some herbal supplements.

With that in mind, Porter has begun asking all of our patients for a list of herbs and vitamins they take at the same time they ask for a list of prescription medicines.

Pharmacy Director Elton VanderTuin says it’s all part of keeping you safe. “We know herbal supplements are very commonplace today,” he says.  “We have begun monitoring their use among our patients to try to prevent interactions with the medications that are being prescribed.”

Mr. VanderTuin says most people believe herbs are harmless plants and aren’t aware that a great many prescription medications were developed from plants.  That includes the powerful heart drug digoxin, which was derived from the beautiful foxglove, as well as the narcotic, morphine, and the stimulant, atropine.  Common, everyday aspirin comes from willow bark. 

Your likelihood of having a reaction depends – in part – on how many over-the-counter medications, prescriptions and herbs, minerals and vitamins you are taking.  If you are consuming two products, your risk of an interaction is 6 percent.  That likelihood of an interaction skyrockets to 50 percent if five products are being consumed and when eight or more products are consumed, the interaction likelihood is 100 percent.

Pharmacists group the interactions into two main categories – those that interfere with the absorption of a prescription and those where the combined effect of the substances is harmful.

Mr. VanderTuin says sometimes by simply timing when you take a prescription and a supplement, you can avoid unwanted side effects.  Other times, it is important to avoid certain herbs when taking prescription medications.

Such is the case for the supplement, licorice, and prescription corticosteroids.  When taken together, licorice decreases the metabolism of corticosteroids, leading to adverse and toxic effects.  That is also the case with the popular herb, St. John’s Wort and the use of digoxin or theophylline.  Science knows that the concurrent use of the two makes the digoxin or theophylline less effective.  That is also the case with ginkgo biloba, which has been shown to increase bleeding among patients who took the herb at the same time they were taking anti-clotting medications, such as aspirin or warfarin (coumadin).

“A patient should always tell their pharmacist and their doctor what herbal supplements they are taking.  You may not think it’s a big problem and it may not be.  But, it’s important that we are able to monitor our patients for side effects,” Mr. VanderTuin says.  “Sometimes, it helps to keep a diary so we can know what experience you are having with the medication and if the supplements you are taking may be causing problems.”