”Herb-Drug Interactions may not be chemical interactions between a drug and an herb which produces something toxic. More usually the interaction may involve having an herb component cause either an increase or decrease activity of a drug in the blood stream. Decreased activity of a drug could be caused when an herb binds up the drug and preventing it from getting into the blood stream from the gastrointestinal tract, or by an herb stimulating the production and activity of enzymes that degrade the drug and prepare it for elimination from the body. An increase in the drug dosage could occur when an herb component aids absorption of the drug, or inhibits the enzymes that break down the drug and prepare it for elimination. A decrease in drug dosage by virtue of an interaction could make the drug ineffective; an increase in drug dosage could make it reach levels that produce side effects. Alternatively, an herb might produce an effect that is contrary to the effect desired for the drug, thereby reducing the drug effect; or, an herb might produce the same kind of effect as the drug and give an increase in the drug effect (without increasing the amount of the drug)”. 

http://www.itmonline.org/arts/herbdrug2.htm

These effects of drug combinations may be quickly apparent or appear only with long term use or under certain conditions such as change of diet or introduction of an herbal remedy. Many of these drugs have not been tested in combination. The number of drugs and the number of combinations would mean testing of each and every combination of up ten or more different modern drugs would be a Herculean task taking thousands of years. Research proves that that herbs or even common foods may increase or decrease the effect of a blood thinner such as Warfarin and lead to either bleeding or formation of clots. Similar reports have been made about herbal interactions with blood pressure medications, anti-infection agents, hormonal treatments and anti-diabetes drugs.

In China, where the study of food and herb interactions has been a component of traditional Chinese medicines for thousands of years, it is common for herbs to be combined with modern drugs if a combination or herbs and drugs is observed to be beneficial. These combinations are often intentional and based on centuries of accumulated knowledge and expertise in observing the interactions of different herbal remedies in the practice of Acupuncture and Traditional Herbal Medicine. Many Chinese doctors observe that herbs can help reduce the undesirable side effects of modern allopathic drugs and help them to perform their function better; in reverse some modern drugs may help to make an herb formula work more strongly and quickly. The attitude of Chinese medicine is that modern drugs are yet more tools, whose interactions with an interactive pharmacopeia used over thousands of years, are to be investigated with interest and caution. Herbal Practitioners are on the alert for interactions both negative and positive. Chinese herbal practitioners commonly do not give out weeks of prescription herbs to a new patient. Rather they may give out three to five days of medicine and then the patient must return to get more. They may get more of the same prescription if the result is perfect, and the need on-going, or the formula may be fine-tuned to the patient’s needs and response. This is in contrast with allopathic prescriptions where prescriptions for conditions deemed to be chronic may continue, with perhaps variations in dosage, for a lengthy period of time. The upside of negative herb-drug interations is the potential for the discovery of beneficial herb-drug interactions. In Chinese culture herbs were the most widely used medical therapy during the 20th Century, because they were inexpensive and herbal medicine was traditionally effective in many situations and commanded respect. Western wonder drugs are a relatively recent addition to the medical field, and the expense of them is still out of reach for many patients who continue to rely on traditional remedies.

 The situation was different in the West. Drugs almost entirely superseded herbs during the 20th Century, and were later reintroduced once allopathic drugs had become the preferred treatments of modern health care. In the West, the replacement of herbs by drugs took place over a period of many decades during which it came to be believed that drugs were more reliable than herbs as their potency could be measured more scientifically and exactly unlike herbs, where the active ingredient of a herb might be affected by seasonal weather variations or harvesting conditions. Unlike substances produced in a sterile laboratory herbs may be contaminated by microbes or other substances during growth or transportation. Preparation of the remedy introduces yet another source of variability. The re-introduction of herbs brought with it suspicions and concerns about their possible unreliability and variation in effects, especially in the case of critical illness, where increased responsibility and liability of doctors for their patient’s wellbeing is another modern issue.

Today, doctors and pharmacists are provided with educational materials outlining potential problems of the interaction of modern prescription drugs with herbs that their patients may be using or thinking about using. Generally, the field of Western herbal medicine has been purged of herbal ingredients containing cardiac glycosides, these being extremely dangerous in the wrong dosages. The original active principles of these herbal preparations are often now reformatted as precisely controlled medical drugs. Herbs which contain coumarins which might act to interfere with with Warfarin, a coumadin (binary coumarin, much more potent than coumarins), or interfere with correct dosage of other blood thinners. However broccoli a common food, usually thought to be generally healthful, can also affect the action of blood thinners by preventing the blood thinning effect.  Tea is promoted as having and antioxidant effect however strong tannins similar to that found in common tea can bind up drugs in the intestinal tract and make them less available. There is mention of the issue of possible interaction of Minor Bupleurum Combination (Xiao Chaihu Tang; in Japan: Sho Saiko To) with interferon in treatment of hepatitis to cause an immune response leading to lung damage. The herb Salvia (danshen) or the food supplement Chia Seed can act in combination with Warfarin, leading to excessive blood thinning. Rather than seeing such interactions as a source of fear, this information should impress on us the potential medical effect and remarkable healing power contained in even common foods and condiments. Problems can occur when people whose health is fragile experiment with self-medication using herbs instead of consulting a person properly trained in herbal medicine.

For example here are a number of known problems with popular often well promoted herbal remedies. Echinacea may cause inflammation of the liver if used with certain other medications, such as anabolic steroids, methotrexate or others. Ephedra may interact with certain antidepressant medications or certain high blood pressure medications to cause dangerous elevation in blood pressure or heart rate or death in certain individuals. Feverfew, garlic, ginger, and gingko biloba  may increase bleeding, especially in patients already taking certain anti-clotting medications. Goldenseal may worsen swelling and/or high blood pressure. Interactions promoting bleeding have been noted between Gingko and Aspirin. Consumption of Aspirin may thwart attempt to lose weight. And so the list goes on with Warfarin the most common drug, and St. John’s Wort was the most common herbal product reported in drug-herb interactions.

To create a comprehensive and valid list of herb-drug interactions would require a substantial increase in research activities in this area. Not surprisingly, the main drug of concern is Warfarin, which displays substantial sensitivity to interactions with foods and drugs, and which is very widely used (giving more opportunities to note interactions). This suggests that Warfarin might even be able to be avoided if foods, containing predictable amounts of such blood thinners were consumed with regularity and before a person became critically ill. If a patient asks to assure that herbs prescribed will not interact or be a problem with a drug regimen being used at the same time, it is not possible to give such assurances. It is necessary to continue monitoring for potential interactions by maintaining regular blood testing, or in the case of Chinese herbal medicine, to practice routine response observation including the observation of the pulse, the tongue, the eyes, the skin colour and other indicators.

Practitioners of Western allopathic medicine seem less aware than those of Traditional Chinese Herbal Medicine that a patient may have a very unique response to an herbal/drug regime and that it is possible that two patients with the same type of symptoms may require individual herbal prescriptions based on individual latent bodily strengths or weaknesses, not presenting overt symptoms at the time.  Absence of a report in literature doesn’t guarantee that there is no possibility of an herb-drug interaction in any given individual. All methods of health care based on statistics are meaningless to an individual afflicted with an unexpected reaction to a combination of medicines whether allopathic or herbal. According to Ashleigh Brilliant it is prudent to “always expect the unexpected”.

Therefore, if adding an herbal remedy to one’s diet, one should continue to monitor one’s overall health and any conditions being treated by drugs, and one should continue all scheduled blood tests that might help confirm that there have been no problems that might be attributed to herb-drug interactions (e.g., weekly blood coagulation tests, daily monitoring of blood sugar or blood pressure). This can be especially important for drugs with narrow therapeutic windows or drug regimens administered to sensitive individuals for instance older adults, the chronically ill, or those with compromised immune systems. Authorities seem to quite often use relatively rare incidents of catastrophic herb/drug interactions to discourage the public from incorporating herbs into a preventative health routine. But rather than rejecting herbal medicine as old fashioned and dangerous would it not be better to learn caution from these examples and continue to upgrade our the rich database of records of herbal interactions such as is contained in chinese herbal medical records.  

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