Drug-Herb-Nutrient Interactions: Facts You Need to Know
This article was carefully researched and written by Sarah Abernathy, the co-author of Healthy Healing 14th Edition and managing editor of healthyhealing.com.
Do you worry that the herbal remedies, high potency vitamins, and supplements you’re taking could interact with prescription drugs? You’re not alone. Nearly every day, someone contacts my research department to ask whether they can use herbal therapies with prescription drug treatments.
As the lines blur between supplements, natural remedies and drugs, the answers aren’t simple. Opinions on the topic vary widely in both the natural healing and medical worlds. Some practitioners advise against using herbs and supplements altogether while on drug therapy; others routinely recommend them, especially if a drug is leaching nutrients from the body or causing side effects. Adding to the confusion, almost every day brings a new media report, oftentimes biased or incomplete, on the hazards of combining herbs with drugs.
Confused about a safe choice? Here’s what you need to know about drug-herb-nutrient interactions.
Investigating how herbs and nutrients interact with drugs is a new research area with few qualified experts. Knowledge comes slowly and laboriously. Drug and herbal companies move in different worlds, so information is hard to gather and analyze. The learning curve on the safety of each herb-nutrient-drug combination is complex. Much of the information we have on herb-nutrient-drug interactions comes from anecdotal reports or small tests. It’s a detailed, complex subject that will eventually need millions of university grant dollars to determine which herbs and nutrients interact with which drugs. One major obstacle? Neither orthodox medicine nor the natural healing world has a vested interest in funding such research.
Much of the information we do have on drug-herb interactions comes from anecdotal reports or small tests with standardized plant constituents, not whole herb combinations that are routinely recommended by practicing herbalists, acupuncturists and traditional naturopaths. In other cases, information is based on theory about potential interactions, but with no reports actually confirming the interaction. Since drugs as chemicals work outside the system, and whole herbs as foods are processed through our enzyme system, a theorized interaction often never occurs or is neutralized. In some cases, a drug-herb interaction occurs because an herb is misused, taken in very high doses or combined with a medication that has a similar effect (i.e. combinining blood thinning drugs with blood thinning herbs).
In many cases, herbs and supplements can be used supportively, to maintain health while a person is on drug therapy. For instance, ginkgo biloba may be taken to help counteract the sexual side effects of anti-depressant drugs. B-complex vitamins are widely known to reduce drug-induced nutrient depletion from medications like oral contraceptives, estrogen replacement drugs, and methotrexate. There are even cases where an herbal formula can be used to help a person wean off a drug medication, but these cases should always be monitored medically.
Drug-Herb-Nutrient Interactions to be aware of
Drug, herb, nutrient, interactions are rare but can happen. A new 2004 review published in Archives of Internal Medicine shows that in 94% of cases, these interactions are fortunately, not serious.The following list is a good sampling of the known negative interactions between the herbs, nutrients, and prescription medications you may be taking. Ultimately, the decision to use herbal supplements while on prescription drug therapy is a personal one, and one I recommend you make with your physican’s counsel.
St. John’s Wort: St. John’s wort has become an herbal boon for depression in the modern world. Some research shows this herb’s anti-depressant effect rivals conventional anti-depressant drugs for mild to moderate depression! This is certainly good news for people who want a natural alternative to drugs like Prozac which can cause side effects like low libido, agitation or fatigue.
However, standardized St. John’s wort can interfere with many prescription medications. New research reveals St. John’s wort can decrease effectiveness of HIV drugs, drugs for organ transplants and cancer, digoxin, statin drugs, warfarin, chemotherapy drugs, tricyclic antidepressants, asthma medicines, and, possibly, oral contraceptives (although this effect has not proven). Some doctors advise against using the herb before surgery because it reduces effectiveness of the new anesthetics.
Don’t use St. John’s wort if you’re taking antidepressant drugs. The combination of St. John’s wort and drugs that affect brain serotonin levels (like SSRI antidepressants) may lead to ³serotonin syndrome,² a serious condition marked by confusion, incoordination, and cardiovascular irregularities. Several documents report this interaction. St. John’s wort is also contraindicated for people taking anti-depressant MAO inhibitors (monoamine oxidase inhibitors) because it is believed the herb may interact with them, too. New research from Ireland concludes these interactions are rare, and that St. John’s wort actually has fewer side effects and health risks compared to conventional antidepresssant drugs (McIntyre 2000). For some people, whole St. John’s wort may be the best choice for relief of mild to moderate depression, especially if a recommended prescription antidepressant causes long term toxicity to the liver or kidneys.
Be aware that standardized St. john’s wort can have side effects. Photosensitivity is a big problem, especially if it is combined with other photosensitizing drugs like antibiotics. In addition, fatigue and gastrointestinal upset occur in some people. Avoid standardized St. John’s wort if you use tanning beds or take drugs that cause photosensitivity. (You might get burned!) Preliminary research suggests high doses of St. John’s wort may also increase the risk of sun-induced cataracts. (Wear sunglasses when using it!) It is not yet known whether whole St. John’s wort used in herbal combinations would have these same side effects or contraindications. Until more research is available, I recommend any person taking multiple prescriptions consult with their physician before using St. John’s wort’s products and be aware of its photosensitivity potential.
Kava Kava: Kava kava has become the herbal answer to Valium in America. Kava helps calm the mind and relax the muscles without causing side effects like over-sedation or addiction. However, kava is not safe for everyone. If you’re drinking alcohol, don’t take kava. Kava can intensify the effects of alcohol. In addition, kava may interact with anti-anxiety medications like buspirone (Buspar), benzodiazepines and anesthetics. Kava should also be avoided by people taking anti-psychotic drugs and Levodopa for Parkinson’s disease.
Recent media reports suggest kava causes liver damage. However, new evidence shows in 27 of the 30 reported cases the people were using other medications or had a history of alcoholism which may have contributed to the liver toxicity. (In the South Pacific where kava is used regularly in high doses, there are few reports of liver toxicity.) Still, until we know more, avoid kava when you drink alcohol, or if you have liver problems, or if you take drugs that affect the liver. Experts theorize that kava may potentially aggravate liver problems in rare cases. Note: Discontinue kava use if you experience warning signs of jaundice like yellowing of the eyes.
Ephedra: Bad press has now stopped the sale of ephedra (ma huang) in the U.S.. I believe the ephedra controversy is a case of a plant being judged for one of its constituents instead of as a whole. Most of the health problems associated with ephedra are actually due to one of its constituents- ephedrine. When used properly, ephedra is the best herbal bronchodilator for respiratory problems like asthma, and a natural thermogenic aid for weight loss.
Some companies used concentrated, standardized extracts of ephedrine, which have a stronger effect on the body than the whole herb. Others used synthetic ephedrine, a drug derived from the plant, and combined it with caffeine or other stimulating drugs in ³herbal ecstasy² compounds. This type of preparation caused dangerous spikes in blood pressure and heart rate, especially in combination with illicit drugs!
Even with whole herb ephedra products, use precautions. Don’t use ephedra if you have heart problems or high blood pressure. Don’t use ephedra-based products continuously because of potential long-term strain on the adrenal glands. Ephedra is contraindicated if you’re pregnant or nursing; taking a MAO inhibitor, stimulant drugs or decongestants; or if you have heart or thyroid disease, prostate enlargement, or diabetes. If these contraindications don’t apply to you, I recommend using ephedra only as a whole herb, in combination with other herbs in expert herbal formulations, or as a weak tea for a limited span of time.
Ginkgo Biloba: Widely used to help reduce age-related problems like poor circulation, heart disease, tinnitus and impotence, ginkgo is best known as an effective herbal ³brain booster² against memory deterioration. While generally very safe, ginkgo’s blood-thinning effects can interact with some anticoagulants like Warfarin and antiplatelet drugs, and over-the-counter drugs like aspirin or ibuprofen. Many experts feel this interaction is actually minor and only occurs in very small percentage of people taking the herb. Still, it is not advised to take ginkgo before surgery without medical supervision.
Note: Many herbs and supplements have mild blood thinning effects and should be used with caution if you’re taking blood thinning drugs or preparing for surgery. High doses of vitamin E, garlic, ginger, bromelain, protease and feverfew may affect bleeding, and should be used with caution. CoQ10 may reduce the effectiveness of blood thinning drugs like Warfarin. Consult with your doctor on the remedies you’re taking.
Ginseng: The world’s most popular herbal energy tonic, every traditional healing culture in the world has a ginseng or ginseng-type plant in it’s medicine chest. Daily ginseng was a necessary matter of life throughout all of China’s long history. At the turn of the 20th century, virtually every Chinese person used ginseng to some extent for their well being, especially as a wellness tonic. Ginseng was also highly esteemed by every Native American culture. Today, ginseng is one of the most extensively researched herbs in the entire world!
Ginseng is so potent, we think of it as a panacea, from which comes its name Panax, an herb to restore and normalize various body functions like blood pressure, blood sugar, energy, and endurance. In one study, people who had taken ginseng for one year had 36% less cancer incidence han non-users. Longer term usage produced even better results. People who had used ginseng for 5 years or more had 69% less cancer incidences. Ginseng is the only plant known that contains phyto-testosterone which stimulates sex drive in both men and women. American ginseng, specifically, has been shown to increase the weight of the seminal vesicles, prostate gland and sperm count.
Still, ginseng may not be appropriate for everyone. New reports suggests that patients with bipolar disorder on antidepressant drug therapy should avoid ginseng as it may provoke a manic state. In addition, a study reported in Annals of Internal Medicine found ginseng reduces Coumadin’s effectiveness, a very dangerous effect for people at high risk for blood clots.
Licorice: Licorice has a long tradition of safe use as a natural antibiotic and antiviral in both Western and Chinese herbal medicine. It’s an American favorite for female hormone balance and adrenal exhaustion. Most people can take licorice without problems, but avoid it if you have high blood pressure or if you take high blood pressure drugs. In very high doses, the licorice constituent, glycyrrhizin, can cause potassium loss, fluid retention and elevated blood pressure. Licorice is not advised for people with a history of renal failure or who take heart medication or steroid drugs.
Feverfew: Traditional herbalists turn to feverfew for migraine relief. Five different studies reveal feverfew is more effective than a placebo at relieving migraine pain, even reducing migraine-related symptoms like nausea, vomiting and sensitivity to light. Some theorize that a combination of NSAIDs (non-steroidal anti-inflammatory drugs) and feverfew may increase the risk of stomach irritation because both substances affect prostaglandins that protect the stomach lining. (NSAIDs by themselves are a clear risk factor for stomach ulcers.) Feverfew can also affect blood clotting. Use with caution if you take like Warfarin or Heparin.
Vitamin A: Supplemental vitamin A is used to counteract night blindness, as an antioxidant in natural cancer treatment, and in creams to prevent wrinkles. But high doses of vitamin A can be toxic and should definitely be avoided during pregnancy. Don’t take vitamin A if you take the prescription drug Accutane for acne. Accutane is structurally similar to vitamin A and has similar toxicities. Avoid vitamin A if you’re under treatment for thyroid cancer. Beta carotene, which is converted to vitamin A in the liver as needed, is a much safer choice for people concerned with vitamin A toxicity.
Ipriflavone: Ipriflavone is a synthetic derivative of soy isoflavones with bone protecting activity. Studies with over 1300 women show ipriflavone can slow osteoporosis progression in post menopausal women. There is some evidence it may even reverse osteoporosis! Animal studies suggest ipriflavone both inhibits bone resorption and stimulates bone formation. Its bone-strengthening effects are improved by adding calcium and vitamin D. A therapeutic dosage is 300mg twice daily.
However, be aware that ipriflavone interacts with some prescription medications by affecting the way they are processed in the liver. For example, ipriflavone can increase the effects of theophylline, caffeine, drugs for epilepsy and diabetes, and blood thinning medications like Coumadin causing potentially dangerous side effects. It’s not a good idea to take ipriflavone if you have liver problems either, because it may build to toxic amounts in the liver. People with serious kidney disease should consult with their physician before using ipriflavone because ipriflavone is metabolized in the kidneys.
Grapefruit Juice: Grapefruit juice is one of the few foods that interacts with prescription drugs. Grapefruit juice causes some drugs to be absorbed too quickly – a dangerous effect for people taking drugs with high potential for toxicity or serious side effects. Don’t drink grapefruit juice if you take calcium channel blockers for high blood pressure. The combination can be fatal! Grapefruit juice can also have dangerous interactions with drugs for allergies like Claritin and Allegra, antihistamines like Benadryl, and high blood pressure drugs. Grapefruit juice may interact with organ transplant drugs, estrogens and oral contraceptives, anti-anxiety medications, Methadone, Viagra, HIV drugs, seizure drugs and statin drugs for high cholesterol. Note: While grapefruit juice has the reputation for interactions, the fruit may have the same effect if consumed in large amounts.
A note on antidepressant MAO drugs (mono amine oxidase inhibitors): MAO’s are a rare class of drugs known to have interactions with foods. People taking MAO inhibitors for depression should avoid foods high in tyramine like cheese, sausage, alcohol, legumes, fish, sauerkraut, soups, and yeast extracts, and the herbs ginseng and scotch broom.
My final word on interactions between drugs, herbs and nutrients?
We have much to learn about how herbs and nutrients interact with powerful prescription drugs. Still, I believe most negative interactions occur when people use highly potent standardized herbs, take extremely large doses of herbs or nutrients, or combine herbs and nutrients with drugs that have innate toxic properties and serious side effects.
There’s no such thing as an essential drug. Drugs don’t play a normal role in human biology. Health problems are not caused by drug deficiencies. Drug side effects occur for this very reason…. because they aren’t part of the normal workings of the body.
Supplements and whole herbs will always be gentler and easier to take than drugs. Sometimes short-term drug therapy may be necessary to stabilize a serious health problem so that immune response can take over for long term health. If you’re on drug therapy or preparing for a medical procedure, talk to your doctor about the natural remedies you’re using and ask about possible interactions. Working with a knowledgable health professional trained in both natural and conventional approaches is by far the best choice. Finding the right blend of medicine for you is worth this extra effort.
– Lininger, Schuyler, D.C., Alan Gaby, M.D., Steve Austin, N.D., Forrest Batz PharmD, Eric Yarnell, N.D., Donald Brown, N.D., George Constantine Rph, Ph.D. A-Z Guide To Drug-Herb-Vitamin Interactions. Healthnotes, Inc. 1999.
– Harkness, Richard, Pharm.,FASCP & Stephen Bratman, M.D. Drug-Herb-Vitamin Interactions Bible. Prima Health, 2000.