When we wrote The People’s Guide to Deadly Drug Interactions, we included a section on herb-drug combinations. We were concerned about the possibility that many people would take herbs along with their medications without realizing that there could be a risk of incompatibility.
We have become even more alarmed about this potential danger as we have collected the information for this book. Many herbs impact a variety of biochemical systems and could have a profound effect on the way drugs exert their activity. Unfortunately, drug companies have little incentive to do the research that would tell us more about such interactions. And herb manufacturers rarely have the resources or the inclination to explore this crucial area themselves. With 60 million people now regularly taking herbs and dietary supplements and also utilizing prescription and over-the-counter medicines, the possibility for dangerous interactions is great.
Each herb summary in the last section of this book contains information on interactions. We encourage you to consult this information before combining any drugs with herbal remedies. Please recognize that not all interactions have been discovered or reported in the literature. Knowledge in this field is constantly changing, so there may be interactions we have not been able to include. Here are just a few of the more alarming combinations:
LICORICE AND LANOXIN
Licorice may seem like an innocuous candy, but the herb has very powerful hormone like effects. Regular use of this herbal medicine can deplete the body of potassium. In combination with the heart drug Lanoxin, a low potassium level could disrupt the heart’s regular rhythm. This interaction is especially dangerous if a person is also taking diuretics such as hydrochlorothiazide or Lasix that cause potassium loss. Strong herbal laxatives such as senna, cascara sagrada, or aloe could also throw body electrolytes like potassium out of balance and make the combination of licorice and Lanoxin potentially deadly. Even without Lanoxin, taking licorice with aloe or senna could trigger a life-threatening arrhythmia.
KAVA AND XANAX
Kava-kava is one of the most sedating herbs people can use to help them sleep or cope with anxiety. One person thought he would switch to this herb but started using kava while he was still taking Xanax (alprazolam). He experienced a coma like episode as a consequence of this combination and ended up in the hospital. Kava might interact in a similar way with other anti anxiety drugs such as chlordiazepoxide (Librium), diazepam (Valium), flurazepam (Dalmane), halazapam (Paxipam), lorazepam (Ativan), and temazepam (Restoril). Valerian, another herbal sedative, may also interact with these drugs or with kava-kava. We recommend against mixing either of these herbs with each other, with alcohol, or any other sedating compound, including diphenhydramine. This is found in many nighttime pain formulas such as Tylenol PM.
ST. JOHN’S WORT AND PAXIL
St. John’s wort definitely modifies brain chemistry. Its effectiveness as an antidepressant depends on such activity. One woman who took Paxil together with St. John’s wort became groggy and incoherent. She was also nauseated, weak, and so tired she could hardly get out of bed. With millions of people taking antidepressants such as Prozac, Paxil, and Zoloft, we fear that this interaction may become more common. It is potentially dangerous. Please do not combine St. John’s wort with any prescription antidepressants unless a knowledgeable health professional is carefully monitoring your progress. St. John’s wort may also affect the metabolism of medications such as olanzapine (Zyprexa) and other antidepressants like amitriptyline (Elavil) and imipramine (Tofranil). Other drugs that may be affected by this herb include caffeine, clozapine (Clo-zaril), haloperidol (Haldol), theophylline (Theo-Dur), warfarin (Coumadin), and zileuton (Zyflo). Ginkgo, kava, and valerian may also affect these drugs. Blood levels of the medications may rise, potentially increasing the risk of reactions. We are very concerned about another interaction with St. John’s wort, with light rather than medication. Joan Roberts, Ph.D., of Fordham University, has been studying the effects of light and drugs on the eye for decades. She has discovered that hypericin, an ingredient in St. John’s wort, reacts to ultraviolet and visible light. When activated, hypericin becomes toxic to the lens and retina of the eye, increasing the risk of cataracts or macular degeneration over time. Because sunglasses don’t screen out visible light, they can’t protect people from this danger. We suggest that people taking St. John’s wort stay out of bright light completely.
GINKGO AND COUMADIN
Ginkgo has an impact on blood clotting by affecting something called PAF (platelet activating factor). We fear that combining ginkgo and Coumadin, a powerful anticoagulant, may increase the risk for bleeding. In fact, several cases have been reported in which people taking ginkgo and Coumadin have suffered hemorrhages. Other herbs that may also increase the action of Coumadin include cayenne, chamomile, dong quai, echinacea, feverfew, garlic, ginger, hawthorn, horse chestnut, juniper, and licorice. Herbs that may counteract Coumadin include ginseng, goldenseal, and pau d’arco. Anyone taking Coumadin and herbs needs to have very careful blood monitoring frequent tests for blood clotting (prothrombin times and INR).
Aspirin has blood-thinning power and might also interact with many herbs, including ginkgo, garlic, feverfew, ginger, hawthorn, juniper, and licorice. One man began bleeding inside his eye after starting on ginkgo in addition to his regular aspirin therapy.
MA HUANG AND ANTIDEPRESSANTS
Ma huang, also known as ephedra, must never be combined with MAO inhibitors such as Marplan, Nardil, or Parnate, used to treat depression. This interaction could send blood pressure dangerously high. Do not take ma huang within two weeks of using an MAO inhibitor. Deaths have been reported with use of ma huang. Yohimbe, an herbal treatment for impotence, is also potentially dangerous with MAO inhibitors. Ma huang is incompatible with heart medicines such as Lanoxin and with the anesthetic halothane. Serious disruption of heart rhythm may occur. Ma huang must not be combined with ergot or its derivative ergotamine (Cafergot), or blood pressure could become very elevated.
Glucomannan, a dietary fiber sometimes recommended for weight loss, can lower blood sugar. Diabetics using this fiber need to monitor blood sugar more closely. The dose of diabetes medicines such as DiaBeta, Diabinese, Dymelor, Glucotrol, Glynase, Micronase, Orinase, Tolamide, or Tolinase may need to be adjusted. Another diabetes pill, Glucophage, may not be absorbed as well if it is taken before a meal containing a different dietary fiber, guar gum. This thickener is used in salad dressing, frozen yogurt, and other low-fat foods to improve their texture.