Some herbal supplements can have dangerous interactions with heart medications.By Mayo Clinic staff Herbal supplements are natural, so they must be safe, right? Not necessarily. Herbal supplements can have strong effects in the body, and some can interact with prescription medications used to treat heart and circulatory problems, such as high blood pressure and heart failure. Some of these interactions can even be dangerous.
Herbal supplements and prescription medicationsAt least a quarter of adults who take prescription medications also take dietary supplements, including herbal supplements. That number is even higher among adults older than age 70 — three-quarters report using both prescription medications and dietary supplements.
Yet many herbal supplements interact with medications for cardiovascular disease — which are widely prescribed for older adults. The chances of herbs and drugs interacting are high. Indeed, 8 of the 10 most widely used supplements interact with the blood-thinning medication warfarin (Coumadin). Here are just a few of the herbal supplements that can affect warfarin:
- Dong quai
- Evening primrose oil
- St. John's wort
This table shows popular herbal supplements and interactions with common heart medications. It's not a complete list, however, so be sure to discuss with your doctor the medications and supplements you take.
|Herbal supplement||Medication||Potential effect|
||Increases risk of bleeding|
||Increases risk of bleeding|
||Decreases effectiveness of warfarin|
||Increases blood pressure and heart rate|
||Decreases blood pressure|
||Increases effects of digoxin|
||Decreases levels of warfarin|
|St. John's wort||
||Reduces effectiveness of drugs|
Playing it safe with herbal supplementsIf your doctor tells you it's OK to use an herbal supplement combined with a medication, make sure you follow dosing instructions carefully. Watch for any unusual signs or symptoms that you could be having a drug interaction, such as rapid heartbeat, low blood sugar or changes in blood pressure.
Last Revised: April 26, 2012Author: Healthwise Staff
Medical Review: Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Margaret Hetherington, PHM, BsC - Pharmacy
Garlic, ginkgo, St John's Wort could all upset bleeding/clotting balance, study found
THURSDAY, May 13 (HealthDay News) -- People taking the prescription blood thinner warfarin (Coumadin) may up their risk for health complications if they also take herbal or non-herbal supplements, new research reveals.
In fact, eight out of the 10 most popular supplements in the United States could spark safety concerns with respect to warfarin, while also impacting the drug's effectiveness.
"I specifically looked at warfarin use, but the real issue is that even though herbal supplements fall under the category of food, and they're not regulated like prescription drugs, they still have the effects of a drug in the body," cautioned study author Jennifer L. Strohecker, a clinical pharmacist at Intermountain Medical Center in Salt Lake City.
"Warfarin is a very high-risk medication, which can be associated with severe consequences when it's not managed properly," she added. "However, warfarin is derived from a plant, sweet clover. In fact, many of our prescription drugs came from plants. So, it's very important for patients to recognize that just because an herb is marketed not like a prescription drug [that] doesn't mean it doesn't have similar effects in the body."
Strohecker and her colleagues are slated to present their findings Thursday at the Heart Rhythm Society annual meeting in Denver.
The authors note that almost 20 percent of Americans currently take some type of herbal or non-herbal supplement.
To gauge how these products might interact with warfarin, the researchers ranked the 20 most popular herbals and 20 most popular non-herbal supplements based on 2008 sales data, and then looked at how their use affected both clotting tendency and bleeding.
More than half of the herbal and non-herbal supplements were found to have either an indirect or direct impact on warfarin. Nearly two-thirds of all the supplements were found to raise the risk for bleeding among patients taking the blood thinner, while more than one-third hampered the effectiveness of the medication.
An increase in bleeding risk was specifically linked to the use of cranberry, garlic, ginkgo and saw palmetto supplements, the team said.
Glucosamine/chondroitin, essential fatty acids, multi-herb products, evening primrose oil, co-enzyme Q10, soy, melatonin, ginseng and St. John's wort all affected warfarin's effectiveness so much so that they prompted a need for adjustments in the drug's prescribed dosage.
"I'm not against herbal supplement use at all," Strohecker stressed. "But physicians need to proactively discuss this issue with their patients because of the consequences that can occur."
Dr. Richard L. Page, a cardiologist and chair of medicine at University of Wisconsin, Madison, and president of the Heart Rhythm Society, believes the larger problem here is poor patient-doctor communication.
"Doctors don't always know what their patients are taking," he said. "Supplements may perform a very good service. Or they may not be providing the sort of care that patients are looking for when they're essentially self-medicating. And where this becomes especially important is that these supplements can interact with the prescription drugs that your doctor may be giving you."
"This report is important," Page said, "because they look at a very common drug, warfarin, which has a narrow therapeutic window. Which means too much is bad cause you bleed, and too little is bad because it won't do the job of thinning the blood that you want. So the bottom line is, be careful of adding new supplements if you are on existing prescription medications, and talk to your doctor if you do."
A representative of the supplements industry took a slightly different view.
Duffy MacKay, vice president of scientific and regulatory affairs for the D.C.-based Council for Responsible Nutrition, the leading dietary supplement industry trade association, said that, "the issue here is really more with warfarin."
"It's just a very sensitive medication," he said. "Warfarin itself has a huge list of drugs, foods and over-the-counters that it interacts with. If you take too much or too little, it can become dangerous."
"So it's sort of a form of sensationalism to suggest that here you have this situation with dietary supplements specifically," MacKay added.
There's more on warfarin at the U.S. National Institutes of Health.
Researchers Say Some Supplements Should be Avoided by Patients Taking Heart Drugs
Investigators with the Mayo Clinic identified herbal and alternative products that they say should be avoided by patients with heart disease.
They claim the products could cause problems when taken with drugs commonly prescribed to lower blood pressure, control cholesterol, stabilize heart rhythms, or prevent blood clots.
The research analysis appears in the Feb. 9 issue of the Journal of the American College of Cardiology.
Researcher Arshad Jahangir, MD, tells WebMD that heart patients often fail to tell their doctors about the alternative remedies they take because they don't recognize the potential for harm.
"Many people think that natural is synonymous with safe," he says. "Many of these herbal remedies have been used for centuries, but they may not be safe in the current era when used by patients taking many other medications."
Older Patients Most at RiskJahangir says the danger is especially great in elderly heart patients, who are often also taking drugs for other chronic conditions and who may already have an increased risk for bleeding.
Bleeding was one of the most frequently cited interaction risks identified by the Mayo researchers, along with reducing or increasing the potency of the prescribed medications.
Some specific examples they cited included:
- St. John's wort, which is typically used to treat depression, anxiety, and sleep problems, has been shown in some studies to decrease the effectiveness of the arrhythmia drug digoxin, as well as blood-pressure-lowering medications and cholesterol-regulating statins.
- The herbal remedies alfalfa, dong quai, bilberry, fenugreek, garlic, ginger, and ginkgo biloba were all identified by the researchers as increasing bleeding risk when combined with the widely prescribed anti-clotting drug Coumadin (warfarin). Ginseng and green tea were identified as decreasing Coumadin's effects.
- The banned herbal product ephedra (ma-huang) has been linked to stroke, heart attack, seizures, and death from cardiac arrhythmia in otherwise healthy adults who used the product to boost energy or lose weight.
Jahangir says taking heart medications with grapefruit juice is a common cause of drug toxicity.
For almost two decades, researchers have known that grapefruit juice can increase dosages of some drugs to toxic levels by inhibiting a key enzyme in the intestine that breaks down medications.
He says patients on cholesterol-lowering statins who take the drugs with grapefruit juice may end up with blood statin levels that are three to four times higher than intended.
"I think it is a good idea for anyone taking medication to avoid grapefruit juice because the effects can last as long as 24 hours," he says.
The Mayo researchers conclude that there is a clear need for increased regulation to protect the public from herbal and alternative supplements that can harm them.
Supplement Industry ReactionA spokesman for the dietary supplement industry's leading trade group was highly critical of the claim and the research analysis in general in a written statement released today.
Council for Responsible Nutrition Vice President for Scientific and Regulatory Affairs Douglas MacKay, ND, writes that the analysis represents a "biased, poorly written and contrived attack on herbal supplements," which contained "sweeping generalizations, often not backed by relevant citations, and copious factual errors."
He faults the researchers for not acknowledging recent changes in federal law that require dietary supplement manufacturers to report serious adverse events to the FDA.
According to MacKay, in the first full year the law was in effect, the FDA reported 1,080 adverse events linked to the use of vitamins and minerals, as well as herbal, sports, and weight loss supplements. A total of 672 adverse events were considered serious.
"For the same year, FDA received over 526,000 adverse event reports related to drugs and biologic products, overn 300,000 of which were considered serious, including close to 50,000 deaths," he writes.