Some combinations of herbal supplements and drugs for heart conditions can be deadly

The older you get, the greater your chance of being treated for a cardiovascular condition, such as high blood pressure, heart attack, heart failure and heart rhythm abnormalities.

Fortunately there are many medications available to treat these conditions. But many patients—and their doctors—aren’t aware that many of these medicines interact with over-the-counter herbal supplements. And some of those interactions are deadly.

What is an herbal supplement, anyway? Simply defined, it’s any part of a plant or a plant product. They are not subject to the same regulations as drugs. The only requirement is that the manufacturer sends a copy of the label to the U.S. Food and Drug Administration (FDA). The ingredients are not tested for safety or efficacy. The ingredients can be new and experimental. A lack of quality control means that labeling can be inconsistent and the actual amount of ingredients can vary widely from lot to lot. Repeated studies have shown that contamination with heavy metals, adulteration with pharmaceuticals and prohibited ingredients are often found.

Even though herbal products are touted as “natural,” they may still cause adverse reactions in some patients. The true incidence of such reactions is underreported for several reasons. First, patients who assume that herbal supplements are always safe often don’t recognize that a problem that they experience may be due to a supplement. So the patient doesn’t report the event to the FDA, the manufacturer or the doctor. Patients often don’t think to report supplement use to their health care providers, and providers often fail to specifically ask about supplement use.

Two common medications in particular that are susceptible to interactions with herbals are the blood thinner warfarin (Coumadin) and digoxin used to treat failing heart muscle and certain abnormal heart rhythms. If an herbal medicine increases the metabolism of warfarin, the drug will be less effective, and the patient may experience the unwanted blood clotting that warfarin is supposed to protect against. This can cause stroke, as well as blood clots in the legs, lungs or arteries of the heart. Conversely, some herbals slow the metabolism of warfarin, which permits higher levels to accumulate, leading to increased risk of bleeding. This can cause strokes due to bleeding within the brain, gastrointestinal bleeding and other unwanted bleeding.

Herbals that alter the metabolism of digoxin can cause heart rhythm abnormalities and other heart problems. If an herbal raises the digoxin level, a patient can develop the signs of digitoxicity: confusion, nausea and vomiting, palpitations and serious abnormal heart rhythms, and vision changes.

Herbal products can affect other drugs used to treat cardiovascular conditions. This includes, but isn’t limited to, beta-blockers, antiarrhythmics, and cholesterol lowering drugs.

Be sure to tell your doctor if you are taking any herbal supplements!

One common herbal preparation is St. John’s wort, purported to treat depression, insomnia, anxiety and other conditions.

This medicine affects an enzyme called CYP3A4, which metabolizes approximately 50 percent of all prescription medications. St. John’s wort increases this enzyme, hastening the elimination of drugs metabolized by CYP3A4, and reducing their effectiveness. St. John’s wort markedly decreases the level of the anti-rejection drug cyclosporine, used after organ transplant, and has caused organ rejection.

Another popular supplement is ginkgo. It’s claimed to alleviate the symptoms of Alzheimer’s disease, but there is no convincing evidence yet that it is effective for this disorder. But when taken along with many medicines used to decrease the risk of blood clots, it can increase the risk of unwanted bleeding. Bleeding has been reported in the brain, in the eye and the abdomen.

Echinacea is popular because it is alleged to stimulate the immune system and prevent infections. Evidence so far shows no benefit in treating or preventing infection with rhinovirus, the virus that causes the common cold. But if used for long periods, it can increase the risk of liver damage due to certain medications, especially those used to lower cholesterol.

While herbal medicines are growing in popularity, remember that their purity, effectiveness, and safety are often unknown. Until these products are better studied and regulated, wise consumers should be aware that they are using them at their own risk. If you take any prescription medications, be sure to let inform your prescriber about use of herbals. It could save you from a dangerous drug interaction, or even save your life.

Eva Briggs, a board-certified physician, works on the staff at Cayuga Medical Center in Ithaca, in its two urgent care centers: one in Ithaca, and the other in Cortland.