Herbalism

Herbalism is a traditional medicinal or folk medicine practice based on the use of plants and plant extracts. Herbalism is also known as botanical medicine, medicinal botany [1], medical herbalism, herbal medicine, herbology, botanical medicine and phytotherapy. Sometimes the scope of herbal medicine is extended to include fungi and bee products, as well as minerals, shells and certain animal parts.

Plants have an almost limitless ability to synthesize substances that are useful to the maintenance of health in humans and other animals. These include aromatic substances, most of which are phenols or their oxygen-substituted derivatives such as tannins. Many are secondary metabolites, of which at least 12,000 have been isolated, a number estimated to be less than 10% of the total. In many cases, these substances (esp. alkaloids) serve as plant defense mechanisms against predation by microorganisms, insects, and herbivores. Many of the herbs and spices used by humans to season food yield useful medicinal compounds.

People in all continents have used hundreds to thousands of indigenous plants for treatment of ailments since prehistory. There is evidence from the Shanidar Cave in Iraq, that suggests Neanderthals living 60,000 years used medicinal plants. The body unearthed had been buried with eight species of plants which are still widely used in ethnomedicine around the world. [2]

The first generally accepted use of plants as healing agents was depicted in the cave paintings discovered in the Lascaux caves in France, which have been radiocarbon dated to between 13,000 - 25,000 BC. Medicinal herbs were found in the personal effects of an "Ice man," whose body was frozen in the Swiss Alps for more than 5300 years which appear to have been used to treat the parasites found in his intestine.[3]

Anthropologists theorize that over time, and with insight, instinct and trial and error, a base of knowledge would have been acquired within early tribal communities. As this knowledge base expanded over the generations, the specialized role of the herbalist emerged. The process would likely have occurred in varying manners within a wide diversity of cultures.

Indigenous healers often claim to have learned by observing that sick animals change their food preferences to nibble at bitter herbs they would normally reject. Field biologists have provided corroborating evidence based on observation of diverse species such as chimpanzees, chickens, lambs and butterflies. Lowland gorillas takes 90% of their diet from the fruits of Aframomum melegueta, a relative of the ginger plant, that is a potent antimicrobial and apparently keep Shigellosis and similar infections at bay. [4] Researchers from Ohio Wesleyan University found that some birds select nesting material rich in antimicrobial agents which protect their young from harmful bacteria.[5] Sick animals tend to forage plants rich in secondary metabolites such as tannins and alkaloids. Since these phytochemicals often have antiviral, antibacterial, antifungal and antihelminthic properties, a plausible case can be made for self-medication by animals in the wild. [6] Some animals have digestive systems especially adapted to cope with certain plant toxins, such as the koala that can live on eucalyptus, a plant that is dangerous to most animals. While a plant that is harmless to a particular animal may not be safe for humans to ingest, the medicine people in indigenous tribes traditionally collected and passed on safety and cautions.

The use of herbs to treat disease is almost universal among non-industrialized societies. A number of traditions came to dominate the practice of herbal medicine in the Western world at the end of the twentieth century:

The Western, based on Greek and Roman sources,
The Ayurvedic from India, and
Chinese herbal medicine (Chinese herbology).
Unani-Tibb medicine
Shamanic Herbalism
Simple Herbalism
Many of the pharmaceuticals currently available to Western physicians have a long history of use as herbal remedies, including opium, aspirin, digitalis, and quinine. The World Health Organization (WHO) estimates that 80 percent of the world population, presently use herbal medicine for some aspect of primary health care. Herbal medicine is a major component in all traditional medicine systems and a common element in Ayurvedic, homeopathic, naturopathic, traditional Chinese medicine, and Native American Indian medicine. According to the WHO, 74% of 119 modern plant-derived pharmaceutical medicines are used in ways that correlated directly with their traditional uses. Major pharmaceutical companies are currently conducting extensive research on plant materials gathered from the rainforests and other places for possible new pharmaceuticals.[7]

The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Pharmacologists, microbiologists, botanists, and natural-products chemists are combing the Earth for phytochemicals and leads that could be developed for treatment of various diseases. In fact, approximately 25% of modern drugs used in the United States have been derived from plants.

Three quarters of plants that provide active ingredients for prescription drugs came to the attention of researchers because of their use in traditional medicine.
Among the 120 active compounds currently isolated from the higher plants and widely used in modern medicine today, 75 per cent show a positive correlation between their modern therapeutic use and the traditional use of the plants from which they are derived.
More than two thirds of the world's plant species - at least 35,000 of which are estimated to have medicinal value - come from the developing countries.
At least 7,000 medical compounds in the Western pharmacopoeia are derived from plants[8]

All plants produce chemical compounds as part of their normal metabolic activities. These can be split into primary metabolites, such as sugars and fats, found in all plants, and secondary metabolites found in a smaller range of plants, some useful ones found only in a particular genus or species.

The autologous functions of secondary metabolites are varied. For example, as toxins to deter predation, or to attract insects for pollination. It is these secondary metabolites which can have therapeutic actions in humans and which can be refined to produce drugs. The word drug itself comes from the Swedish word "druug", which means 'dried plant'. Some examples are inulin from the roots of dahlias, quinine from the cinchona, morphine and codeine from the poppy, and digoxin from the foxglove. The active ingredient in Willow bark, once prescribed by Hippocrates, is salacin, or salicylic acid alpha-hydroxybenzoic acid, C6H4(OH)(COOH). S.A. led to the development of Aspirin, acetylsalicylic acid, originally a trade name, patented by Bayer.

A survey released in May 2004[9] by the National Center for Complementary and Alternative Medicine focused on who used complementary and alternative medicines (CAM), what was used, and why it was used. The survey was limited to adults age 18 years and over during 2002 living in the United States. According to this survey, herbal therapy, or use of natural products other than vitamins and minerals, was the most commonly used CAM therapy (18.9%)[10] when all use of prayer was excluded.

Herbal remedies are most common in Europe. In Germany, the term apothecary (Apotheke) is still used, and next to prescription drugs one can order essential oils, herbal extracts, or herbal teas. It is even seen as a preferred treatment over the unnecessary overuse of industrialized production of chemical medication.

In the United Kingdom, the training of medical herbalists is undertaken in private colleges. Recently, Bachelor of Science degrees in herbal medicine are offered at Universities such as University of East London, Middlesex University, University of Central Lancashire, University of Westminster, University of Lincoln and Napier University in Edinburgh.

At UCLAN the training of medical herbalists is extensive, and involves the study of anatomy, physiology, biochemistry, pathology, differential diagnosis etc. This enables the herbalist to be able to talk on equal terms with conventional medical practitioners. They learn about when they can treat, and when they should refer. They study the biochemistry of the body and the chemistry and structure of plants. Alongside this, they study traditional herbal medicine: Indications and Actions, and Energetics. They learn to recognise where conventional medical opinion diverges from traditional herbal medicine doctrine. They look at lots of different models for health care. A significant amount of self reflection is required (see http://www.uclan.ac.uk/courses/ug/bsc_hm.htm and http://www.medicalherbalist.eu). A medical herbalist is trained to view a situation from multiple perspectives in a non-dogmatic way.

Medicinal plants can be used by anyone, for example as part of a salad, an herbal tea or supplement, although some herbs considered dangerous are restricted from sale to the public. Sometimes such herbs are provided to professional herbalists by specialist companies. Many herbalists, both professional and amateur, often grow or wildcraft their own herbs. Many common weeds have medicinal properties (e.g. dandelion).

In the herbal "Healing Wise" by Susun S Weed, the three traditions of healing include" the Wise Woman Tradition, the Heroic Tradition, and the Scientific Tradition. The Scientific tradition relies on use of herbal medicines in the form of isolating the active ingredients in herbs, many modern pharmaceuticals are derived from isolating active ingredients from herbs. The Heroic Tradition relies on the belief that the body is dirty and must be cleansed, it promoted the use of purifying herbs and diuretics. The Wise Woman Tradition uses herbs to nourish and tonify the body, herbs are used in the most natural forms possible, and they are used to support the body in healing itself. The Wise Woman Tradition of healing with Herbal Medicine is explained in this article, which includes The Six Steps of Healing by Susun Weed [2]

There are more sophisticated traditional herbal healing methods in Chinese medicine, Eclectic medicine, Cherokee Medicine, Unami Medicine and Ayurveda. In Chinese medicine herbs (which may include animal and mineral parts) are divided into Superior (food grade), Moderate (to be taken for disease for a short time) and Inferior (toxic, short term) grades. Herbal formulas are based upon the organ system which is out of balance, with chief herbs addressing the main complaint, deputy herbs which reinforce the actions of the chief or address other affected organ systems, and servants which may harmonize, balance temperatures or tastes of the herbs, direct them to various parts of the body or assist penetration. Herbal formulas tend to have five to 15 herbs. Eclectic medicine came out of the vitalist tradition, similar to physiomedicalism and bridged the European and Native American traditions. Cherokee medicine tends to divide herbs into foods, medicines and toxins and to use seven plants in the treatment of disease, which is defined with both spiritual and physiological aspects, according to Cherokee herbalist David Winston. [11] [12] Auyrvedic medicine has quite complex formulas with 30 or more ingredients, including a sizable number of ingredients that have undergone alchemical processing, chosen to balance Vata, Pitta or Kapha. [13] In addition there are more modern theories of herbal combination like William LeSassier's triune formula which combined Pythagorean imagery with Chinese medicine ideas and resulted in 9 herb formulas which supplemented, drained or neutrally nourished the main organ systems affected and three associated systems. His system has been taught to thousands of influential American herbalists through his own apprenticeship programs during his lifetime, the William LeSassier Archive [14] and the David Winston Center for Herbal Studies

See also Herbal Administration for the instructional material previously here.

There are many forms in which herbs can be administered. The easiest way and one that still is frequent among indigenous healers is to chew on the plant. The roots of plants like echinacea, the fruit of lycium (goji) plants, the seeds of the emetic lobelia and the resins of myrrh have all been injested directly. On the other extreme is standardization which may boost certain constituents at the expense of others. The following are methods used for herbal administration.

Herbal Infusions and Decoctions

Main article: Tisane

There are two methods of making herbal teas, infusion and decoction. Infusion is steeping lighter parts of the plant (leaves, flowers, light stems) in boiled water for 15 minutes to ten hours. Decoction is simmering tougher parts, such as roots or bark for period of time, ranging from 10 minutes to several days. Herbal infusions and decoctions may be made of simples (single herbs) or formulas. They may use fresh or dried herbs depending upon availability and the properties desired. For instance Chinese formulas made by decocting dry herbs may call for fresh ginger, which is considered less heating than dry ginger. And aromatic herbs like mint may be infused at the end of a decoction.

Herbal tinctures

Steeping a medicinal plant in alcohol extracts the alcohol-soluble principles into a liquid form that can be stored for long periods. Different concentrations of alcohol are used to extract different constituents of the plants. For example; resins require high alcohol content and polysaccharides usually require low alcohol content for optimal extraction. Some herbs, like mushrooms, must be decocted first to release constituents from the chitin. Others require addition of glycerine to keep tannins from binding. In the United States a 1:5 tincture is common while in the UK, a stronger 1:2 tincture is common. Alcohol increases absorption by about 10%, compared to water extraction.

Fluid extracts

"Fluid extract" refer either to glycerites or to stronger herbal tinctures made by distilling off some of the alcohol used in the tincture process. The final result is a liquid plant compound that can be 40 times more potent than a tincture.

Glycerites are herbal extracts that use glycerin as the solvent or preservative. They are very different and often have completely different medicinal properties than alcohol extracts. Glycerin is generally does not extract as well as alcohol, so either substances are decocted and glycerin is mixed with the resultant decoction or is used to preserve. Tinctures may have the alcohol removed after the extraction process and replaced with glycerin which then acts as the preservative. Glycerin inhibits absorption by approximately 30% so higher dosages are required.

Solid extracts

Solid extracts may be made from tinctures just like fluid extracts, but the entire solvent is separated from the plant compound, leaving a soft paste-like solid exract or a dry solid extract that is often as much as 400 times more potent than tinctures.

Many solid extracts are made by cooking the plant material and water slowly over low heat until it forms a paste. Sometimes these are sold with a preservative like glycerine added and sometimes they need to be refrigerated when they are opened (like apple butter).

Powdered herbs and capsules

Herbs are dried and ground to a powdered consistency. Powdered matter can then be compressed into a tablet or put in an empty capsule. Most capsules these days are made from some form of concentrated extract rather than dried plant material. This method bypasses the taste buds which can cue bile and other body functions, so may require larger dosages. It is optimal for foul tasting herbs, high concentration herbs and for travelling.

Powdered extracts are commonly reconstituted in Chinese medicine as teas. Powdered herbs are also used topically as powders.

Herbal compresses

Herbal compresses are an external application made by soaking a cloth in an herbal infusion or decoction. They are taped in place with a moisture barrier to draw out infection or even physical objects like splinters.

Herbal poultices and plasters

Poultices can be made with fresh ground herbal material, but may also have a carrier like flour or honey. They are applied topically, often in conjunction with a heat source. They offer more strength than a compress. Very concentrated poultices made of ground herbs and essential oils are called plasters.

Herbal ointments

An ointment or salve is a semi-solid preparation made with an oil base to be applied to the skin. It offers more portability than a compress but the thicker texture makes it less desirable for hot skin rashes.

Essential oils
Main articles: Essential oil and Aromatherapy
Essential oils are highly concentrated pharmaceutical compounds that are derived from herbs and may be used in conjunction with them. They are rather a potent natural product, primarily used externally but on occasion internally. Because of their concentration there are toxicity and ecology issues that differ from the use of the same plants as herbs. See the main article.

Herbal supplements
Herbal supplements tend to be commercial products in tablet or capsule form manufactured and marketed by the health food industry for sale in retail outlets to the general public, although there are some types that are sold only to healthcare practitioners for prescription.

Herbal supplements are often standardized to contain stated levels of active phytochemicals. Standardization can be done in a number of different ways. Many companies extract the supposedly active constituents and add them back into a base like rice fiber. This is no longer an herbal preparation as the whole herb is no longer present. Some companies follow the same procedure but add the extracted constituent to whole powdered herb. Some companies simply concentrate their whole herb until the desired constituent concentration is reached.

Many herbalists do not agree with the extraction/standardization of active ingredients, preferring instead to use the whole plant.

Examples of herbal medicine

Artichoke and several other plants reduced total serum cholesterol levels in preliminary studies.[16]
Black cohosh and other plants that contain phytoestrogens (plant molecules with estrogen activity) have some benefits for treatment of symptoms resulting from menopause.[17]
Echinacea extracts limit the length of colds in some clinical trials, although some studies have found it to have no effect at lower dosages that are normally given by herbalists.[18]
Garlic lowers total cholesterol levels, mildly reduces blood pressure, reduces platelet aggregation, and has antibacterial properties.[19] It also has strong anti-viral and anti-fungal properties.
Grapefruit seed extract as a natural antimicrobial has minimal effectiveness as an anti-bacterial, anti-parasitic, and anti-fungal herb.[20][21][22][23][24]
Hibiscus sabdariffa Traditionally used for hypertension. [25][26][27]
Nigella sativa (Black cumin) is a general medicinal plant used for diverse ailments such as cough, pulmonary infections, asthma, influenza, allergy, hypertension and stomach ache. The seeds are considered carminative, stimulant, diuretic and galactogogue. It is often taken with honey. Seed powder or oil is externally applied for eruptions of skin.
Pawpaw used for insecticidal purposes (killing lice, worms), as well as cancer treatment and viral infections.
Phytolacca or Pokeweed is used as a homeopathic remedy to treat many ailments. It can be applied topically or taken internally. Topical treatments have been used for acne and other ailments. Internal treatments include tonsilitis, swollen glands and weight loss.
Peppermint tea for problems with the digestive tract, including irritable bowel syndrome and nausea.
Rauvolfia Serpentina, used extensively in India for sleeplessness, anxiety, and high blood pressure. The first proven allopathic medicine for high blood pressure was extracted from this herb.
St. John's wort, has yielded positive results, proving more effective than a placebo for the treatment of mild to moderate depression in some clinical trials.[28]
Valerian root can be used to treat insomnia.
Feverfew can be used to treat migraine headaches.
Saw Palmetto can be used for BPH.
[3]

Lemon juice or apple cider vinegar can be used to treat acne.[citation needed]
Green tea may have an anti-cancer effect ("Inhibition of mammary tumorigenesis in the C3(1)/SV40 mouse model by green tea" Breast Cancer Res Treat. 2007 May 5.) and can heal scars faster.[citation needed]
Lemon grass can lower cholesterol[citation needed]
Honey can be a solution for cholesterol.[citation needed][4]
Stinging Nettle FreshSpecific for hay fever and allergic rhinitis. Also for vaginitis, rheumatoid arthritis, stomatitis, eczema, diarrhea, hemorrhoids, asthma and gout. Tones up the mucous membranes especially where excessive mucus and inflammation are present. An alkalizing diuretic.

Risks and benefits

A common misconception about herbalism and the use of "natural" products in general, is that "natural" equals safe. However many plants have chemical defence mechanisms against predators that can have adverse or lethal effects on humans. Examples are poison hemlock and nightshade, which can be deadly, although they are not sold as herbs. Herbs can also have undesirable side-effects just as pharmaceutical products can. These problems are exacerbated by different controls over purity and inconsistent information on dosage due to the status of herbs in the United States as dietary supplements which are technically not supposed to have medicinal functions. Furthermore, if given in conjunction with drugs, there is danger of 'summation', where the herb and the drug have similar actions and add together to make an 'overdose' or reduction in the effects, particular with the CPY450 pathway.

Chinese medicine treats interactions as belonging to several categories. Herbs may mutually enhance each other,

There is a danger that herbal remedies will be used in place of other medical treatments which have been scientifically tested for safety and efficacy, resulting in the development or worsening of a medical condition which could have been better prevented or treated. There is also a danger that an herbal remedy may itself cause harm which is unanticipated due to a lack of a full understanding of its composition and biochemical effects.

In the UK, the profession's governing bodies such as The College of Phytotherapy Practitioners and The National Institute of Medical Herbalists offer membership, education and certification. A qualified Herbalist will have studied for four years and passed exams in botanical and medical subjects. He or she will be expected to have the required knowledge to prescribe and dispense herbs tailored to the individual, taking into account their medical history and any other medication.

Effectiveness
As noted above, there have been scientific studies which show that certain plant products can cure or prevent certain diseases. The gold standard for pharmaceutical testing is repeated, large-scale, randomized, double-blind tests. Some plant products or pharmaceutical drugs derived from them are incorporated into mainstream medicine. To recoup the considerable costs of testing to the regulatory standards, the substances are patented by pharmaceutical companies and sold for high profit. Pharmaceutical firms argue that the regulations protect public safety. Cynics point out that they have a secondary effect of setting a high financial barrier to competition.

Most herbal traditions have accumulated knowledge without modern scientific controls to distinguish between the placebo effect, the body's natural ability to heal itself, and the actual benefits of the herbs themselves. Many herbs have shown positive results in in-vitro, animal model or small-scale clinical tests. The few randomized, double-blind tests that receive attention in mainstream medical publications are often questioned on methodological grounds or interpretation. Studies tend to carry more weight if they are performed in the same country as the medical scientists evaluating them. Likewise, studies published in wide circulation magazines such as JAMA receive more consideration than those published in specialized herbal journals. Fortunately there is now much scientific research into the action and effectiveness of herbal remedies and many are justifying their traditional use. High quality trials involving proper controls and double blind methods are being increasingly carried out, with many useful results.

Herbalists tend to use parts of plants, such as the roots or leaves but not isolate particular phytochemicals. They argue that the synergy of the combined substances enhances the efficacy and dilutes toxicity. Unfortunately, this assertion is difficult to prove. Western medicine on the other hand prefers single ingredients on the grounds that dosage can be more easily quantified. Dosage is in general an outstanding issue for herbal treatments: while most conventional medicines are heavily tested to determine the most effective and safest dosages (especially in relation to things like body weight, drug interactions, etc.), there are few established dosage standards for various herbal treatments on the market. Furthermore, herbal medicines taken in whole form cannot generally guarantee a consistent dosage or drug quality (since certain samples may contain more or less of a given active ingredient).

The issue of regulation is an area of continuing controversy in the EU and USA. On one end of the spectrum, some herbalists and consumers maintain that traditional remedies that have a long history of use do not require the level of safety testing as xenobiotics or single ingredients in an artificially concentrated form. On the other hand, others are in favor of legally enforced quality standards, safety testing and prescription by a qualified practitioner. Some professional herbalist organizations have made statements calling for a category of regulation for herbal products. Yet others agree with the need for more quality testing but believe it can be managed through reputation without government intervention. Clearly the full debate involves issues of politics, economics and the role of government that are beyond the scope of this article.

In 2004 the National Center for Complementary and Alternative Medicine began funding clinical trials into the effectiveness of herbal medicine.[30]

Surveys of a scientific approach to herbal medicine can be found in the books Evidence-based herbal medicine,[31] and Herbal and traditional medicine: molecular aspects of health.[32]

One problem with relying only upon evidence based research is that few herbs have been studied, many studied are for novel uses and the research is frequently of poor quality, done without assaying the product to ensure the proper identification or concentration, and frequently with dosage levels that are below those commonly used by professional herbalists.[33] For instance, St. John's wort has been used since the time of Hippocrates as a vulnurary and especially for nerve pain, but the evidence based research only covers the more recent uses as an anti-depressant.[34] Ginkgo biloba was used in Chinese medicine for respiratory illnesses using the nut[35], but evidence-based uses refer to its qualities as a memory enhancer or blood thinner.[36] Given the lack of patent protection for very expensive testing, it is unlikely that common uses of easily accessed herbs will have significant double-blind placebo-controlled testing in the forseeable future. In view of the lack of studies, the conclusions of a recent Mao Institute study that 2/3 of adults who took common herbs (except echinacea and ginseng) for reasons other than those shown by double-blind placebo-controlled studies is neither surprising nor necessarily of concern.[37]

The quality of double-blind testing has problems as well. For instance herbs like Eleuthero (Siberian ginseng) are described as ginseng, a totally different species. Recent studies of Echinacea used either unusual forms (the juice, or the root of E. purpurea) and a dosage that is a third of the traditional dosage. [38][39] Herbal studies frequently also have incorrect botanical identifications, small sample sizes and short term frameworks.

Name confusion
The common names of herbs (folk taxonomy) may not reflect differences in scientific taxonomy, and the same (or a very similar) common name might group together different plant species with different effects. For example, in 1993 in Belgium, in a formula created by medical doctors including someTCM herbs for weight loss, one herb (Stephania tetrandra) was swapped for another (Aristolochia fangchi) whose name in Chinese was extremely similar but which contained higher levels of a renal toxin, aristolochic acid; this quid pro quo resulted in 105 cases of kidney damage. Note that neither herb used in a TCM context would be used for weight loss or given for long periods of time. In Chinese medicine these herbs are used for certain forms of acute arthritis and edema

Standards and quality control
The legal status of herbal ingredients varies by country. For example, Ayurvedic herbal products may contain levels of heavy metals that are considered unsafe in the U.S., but heavy metals are considered therapeutic in Ayurvedic medicine.[44] [45] Heavy metals may be processed in such a way as to inactivate negative aspects, which are not recognized in US or European statutes, known as samskaras. [46]

In the United States, most herbal remedies are regulated as dietary supplements. Reports in the media have spread the idea that the herbal medicine industry is not well regulated. In fact, the Food and Drug Administration (FDA) regulates it very closely. The FDA reviews an herbal product's labels, manufacturing standards, and contents. It collects reports of adverse effects, issues warnings, and pulls products off the shelves if problems are reported.[47]

In addition, the National Nutritional Foods Association (the industry's largest trade association), has developed a program to examine the herbal products and factory conditions of its member companies and give them the right to display GMP (Good Manufacturing Practices) seals of approval on their products. This is a fairly comprehensive process which resembles the certification process used to accredit hospitals. The program has been in wide operation since 2002.[48]

In the UK, herbal remedies that are bought over the counter are regulated as supplements,as in the US. However, herbal remedies prescribed and dispensed by a qualified Medical Herbalist, after a personal consultation, are regulated as medicines. A Medical Herbalist can prescribe some herbs which are not available over the counter, covered by Schedule III of the Medicines Act, for example. Forthcoming changes to laws regulating Herbal products in the UK, are intended to ensure the quality of herbal products used. Most Medical Herbalists will be using herbal products from a supplier who already meets these standards.

Medical interaction
In consultation with a physician, usage of herbal remedies should be clarified, as some herbal remedies have the potential to cause adverse drug interactions when used in combination with various prescription and over-the-counter pharmaceuticals. Dangerously low blood pressure may result from the combination of an herbal remedy that lowers blood pressure together with prescription medicine that has the same effect. In particular, many herbs should be avoided during pregnancy.[49] However, most herbal books alert the reader to necessary precautions.

Not all physicians may be familiar with the effects of different types of herbal medicine, but general practitioners should be able to refer patients to a specialist, or investigate the medical literature on their behalf. A qualified Medical Herbalist or AHG Professional member, however, will be familiar with most commonly used medical drugs and their modes of action and therefore will only prescribe herbal remedies which will not interfere with these.

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