Herbalism is defined as the study and use of plant material as food and medicine for healing and health promotion. Both art and science, herbalism has been practiced for centuries. Although botany describes an herb as a low-growing nonwoody plant, herbalists make use of the entire plant kingdom (Meserole 1996). Long practiced outside of conventional medicine, herbalism is rapidly becoming mainstream, as analysis and research of herbal constituents and activities explore their value in the treatment and prevention of disease.

Archeological findings suggest that plants had been used for medicinal purposes long before recorded history. Indigenous cultures (e.g., African and Native American) incorporated herbs into their healing rituals, while traditional medical systems (e.g., Ayurveda and Traditional Chinese Medicine) developed systematic uses for herbal therapies. Ancient Chinese writings from more than 5,000 years ago, and Egyptian papyrus writings, circa 2,000 B.C.E., describe medicinal plant uses (Chavez and Chavez 2000). Ethnobotanists have discovered that widely separated groups of people have a tendency to use the same or similar plants for the same purposes (D'Epiro 1999).

Although most traditional herbal uses were derived through observation, sensory perception, sacred teachings, and intuition (Meserole 1996), Western herbal medicine has been influenced by the development of the scientific method and by subsequent advances in analytical technology. In the early 19th century, when methods of chemical analysis first became available, scientists began manipulating plant materials by extracting their active principal ingredients, and by chemically modifying isolated ingredients to reduce side effects and enhance therapeutic properties. Later, chemists began synthesizing organic compounds, and practitioners began the transition from raw herbs to synthetic pharmaceuticals (Chavez and Chavez 2000). In 1870, the United States Pharmacopeia listed 636 herbal entries; by 1990, only 58 were listed. Some herbs were dropped from the list because they were considered unsafe or ineffective; however, the decline in Western herbalism through the 1930s is due largely to regulatory and economic factors that favored pharmaceuticals and the practitioners trained to use them (e.g., medical doctors) (Meserole 1996; Chavez and Chavez 2000).

Recently, the World Health Organization estimated that 80% of people worldwide rely on herbal medicines for some aspect of their primary health care. In the last two decades in the United States, increasing public dissatisfaction with the cost of prescription medications, combined with an interest in returning to natural or organic remedies, led to an increase in sales of herbal medicines of 59% in 1997 (Chavez and Chavez 2000). In Germany, approximately 600 to 700 plant-based medicines are available and are prescribed by an estimated 70% of German physicians (D'Epiro 1999).

Herbalists often use whole plant extracts containing multiple constituents on the theory that these ingredients collectively reduce the side effects of any individual constituent (a mechanism known as "buffering") and provide synergistic actions as well. In addition, herbs are generally used in combinations, rather than singly. Using several herbs together is likewise thought to augment synergistic activities, enhance efficacy, and reduce toxicity (Vickers and Zollman 1999).

Diagnosis and treatment are based on the herbalist's understanding of the whole person—body, mind, and spirit (Meserole 1996). Diseases are perceived within the context of the entire system, and the diagnosis may include reference to secondary symptoms (e.g., arthritis due to inflammation secondary to poor elimination) (Vickers and Zollman 1999).

Western science ascribes herbal mechanisms of action to plant constituents—carbohydrates, tannins, lipids, volatile oils, resins, steroids, alkaloids, peptide hormones, enzymes, etc. Therapeutic actions of plants may be influenced by: species, variety, and the individual plant itself; habitat, including such variables as weather and climate, companion plants, pests, and soil; composition and constituents; collection, storage, processing, dispensing, and dosing; presence of adulterants, contaminants, or plant disease; the patient's age, health status, disease, and receptivity to healing; the symbolic or cultural significance of the plant; and the placebo effect (Meserole 1996). For most herbal medicines, the exact compound that produces the pharmacological action is unknown and any therapeutic effects are most likely the result of synergistic action among herbal constituents (Chavez and Chavez 2000).

An office visit to an herbalist typically lasts one hour and includes an extended history and physical examination. Particular attention is paid to the patient's general sense of well-being, sleep quality and patterns, diet and appetite, digestion and elimination, exercise habits, and relaxation preferences. Practitioners typically recommend one or more herbs, dietary changes, and lifestyle modifications. Because herbal medicines are slower acting than pharmaceuticals, patients return for follow-up in two to four weeks. Treatment goals are to correct imbalances, resolve patterns of dysfunction, and treat the underlying cause. Symptomatic treatment may also be initiated, as necessary (Vickers and Zollman 1999).

Herbalists treat many conditions such as asthma, eczema, premenstrual syndrome, rheumatoid arthritis, migraine, menopausal symptoms, chronic fatigue, and irritable bowel syndrome, among others. Although herbal preparations are best taken under the guidance of a trained professional, many patients self-medicate with herbals (Vickers and Zollman 1999). Some of the most common herbs and their uses are discussed below.

Ginkgo (Ginkgo biloba), particularly a standardized extract known as EGb 761, appears to offer some benefit in the treatment of Alzheimer's and multi-infarct dementia. Ginkgo crosses the blood-brain barrier, acts as a cerebral antioxidant, and improves cerebral oxygenation (D'Epiro 1999). A 52-week, randomized, double-blind study of 309 Alzheimer's patients given either placebo or EGb 761 (40 mg tid, before meals) revealed consistent improvements in cognitive performance and social function in the EGb 761 group, while the placebo group worsened over the same period. Two hundred and two subjects completed the study (50% of the EGb group; 38% of the placebo group). Other than occasional reports of mild to moderate gastrointestinal symptoms, adverse events in the EGb group were no different from those for the placebo group (Le Bars et al. 1997).

Kava kava (Piper methysticum) is being investigated for its anxiolytic activities. Kava extract (WS 1490), standardized to 70% kavalactones, was compared to placebo in a 25-week double-blind trial involving 101 male and female outpatients diagnosed with one of four anxiety disorders as defined by DSM-III-R diagnostic criteria. The patients in the WS 1490 group started the trial with a mean score of 30.7, and the placebo group with a mean score of 31.4, as assessed by the Hamilton Anxiety Scale. Pronounced improvements were seen in the WS 1490 group in weeks 12 (mean score 13.4) and 24 (mean score 9.7). The placebo group also improved in weeks 12 and 24, but to a lesser extent (mean scores 18.0 and 15.2, respectively). Adverse events in the WS 1490 group occurred in two subjects who experienced stomach upset (Volz and Kieser 1490). A six-week, double-blind, comparison study evaluated the efficacy of kava (210 mg) and either oxazepam (15 mg) or bromezepam (9 mg) in 164 patients suffering from nonpsychotic anxiety, tension, and agitation. At the end of the six weeks, there were no statistical differences among the three groups as evaluated by the Hamilton Anxiety Scale, with each compound effectively reducing anxiety by approximately 10 points (Woelk et al. 1993). This suggests that kava may be at least as good as the benzodiazepines used in this trial for treatment of anxiety.

St. John's wort (Hypericum perforatum) is well known for its antidepressant effects. In 1994, German physicians prescribed St. John's wort more often than any other antidepressant. St. John's wort contains 10 pharmacologically active constituents but is generally standardized to 0.3% hypericin, which may not be the only therapeutic compound involved (D'Epiro 1999). A meta-analysis of 27 randomized studies involving a total of 2,291 patients provides evidence that St. John's wort is significantly superior to placebo in the treatment of mild to moderate depression (Linde and Mulrow 2000). Seventeen trials were placebo-controlled, and ten were comparison studies using pharmaceutical sedatives or antidepressants but not selective serotonin reuptake inhibitors (SSRIs). Study length varied from four to six weeks and patient inclusion criteria were based on conventional classification systems (e.g., DSM-III and DSM-IV). Most outcomes were measured by the Hamilton Depression Scale or the Clinical Global Impressions assessment tools. More recently, in a double-blind, randomized pilot study, St. John's wort was found to be as effective as sertraline, an SSRI, in the treatment of mild to moderate depression (Brenner et al. 2000). Both St. John's wort and sertraline were well tolerated in the latter study.

Valerian (Valeriana officinalis) has had a long tradition as a sleep-inducing agent. Its actions are similar to those of benzodiazepines; however, hangover effects have not been reported (D'Epiro 1999). Valerian is thought to induce an increase in gamma-aminobutyric acid (GABA) levels in brain synapses, thereby inducing an anxiolytic effect (Ernst 1999). A randomized, double-blind, placebo-controlled, crossover study evaluated the short-term (single dose) and long-term (14 days with multiple doses) effects of valerian extract on objective and subjective sleep parameters. Sixteen patients with established primary psychophysiologic insomnia were included in the study. Sleep efficiency was measured by eight polysomnographic recordings: two recordings (baseline and study night) at each time point that valerian and placebo were tested. Other objective sleep structure parameters were measured by sleep-stage analysis and arousal index. Subjective measures included quality of sleep, feeling in the morning, daytime performance, and perceived length of sleep latency and sleep duration. Single-dose valerian resulted in no effects on sleep structure or subjective sleep assessment. Multiple-dose treatment, however, showed a significant increase in sleep efficiency for both placebo and valerian in comparison to baseline polysomnography and parameters describing slow-wave sleep (SWS). Reductions in SWS latency and subjective sleep latency were observed in the valerian group, with an increase in SWS time in bed and a higher correlation coefficient between subjective and objective sleep latencies (Donath et al. 2000).

Echinacea preparations (from Echinacea purpurea and other Echinacea spp.) are reported to have immune-stimulating functions, including increasing the number of leukocytes and spleen cells, and enhancing the activity of granulocytes. In addition, echinacea increases the release of tumor necrosis factor and inhibits hyaluronidase activity, thereby optimizing the ability of the immune system to withstand microbial infections (D'Epiro 1999). In a double-blind, placebo-controlled study of 160 volunteers with flu-like symptoms, echinacea extract demonstrated the ability to reduce both the incidence and severity of cold symptoms (Braunig et al. 1993; Schoeneberger 1992).

Although herbs, when properly prescribed, are generally thought to offer fewer risks than conventional medications, misidentification, mislabeling, self-prescribing, allergic reactions, undeclared additives, and adulterants increase the likelihood of adverse effects (Chavez and Chavez 2000). Other risks involve interactions between herbs and conventional medications (see Contraindications section) and herbal prescribing by unqualified practitioners (Vickers and Zollman 1999). Some known risks of herbal use include dermatitis from garlic (Allium sativum), photosensitivity from St. John's wort, hepatotoxicity from echinacea, excessive sedation from valerian, agitation from feverfew (Tanacetum parthenium), gastrointestinal irritation from chamomile (Matricaria recutita), and hormonal changes from ginseng (Panax spp.) (Miller 1998). In a study involving 3,250 patients, the most frequently reported side effects of St. John's wort included gastrointestinal irritation, allergy, fatigue, and restlessness, with a total of 2.4% (79 patients) reporting such symptoms (Woelk et al. 1994). Valerian has demonstrated paradoxical stimulant effects in approximately 5 to 10% of users (D'Epiro 1999). Ginkgo, along with feverfew, garlic, ginger (Zingiber officinale), and ginseng, may alter bleeding time (Miller 1998).

Most contraindications involve drug-herb interactions. Some of the more important interactions are listed below.

St. John's wort induces the cytochrome P450 system, particularly the subenzyme CYP3A4, resulting in a doubling of CYP3A4 activity. This effect has significant ramifications for clearance and efficacy of medications also metabolized by this system (McIntyre 2000). In particular, NIH researchers investigating a possible interaction between St. John's wort and the protease inhibitor indinavir found that plasma concentrations of indinavir dropped significantly from levels obtained prior to the introduction of this herb. The Food and Drug Administration (FDA) has issued a public health advisory concerning this interaction based on the study results. (See monograph on St. John's wort for further details.) Also reported in the same monograph is a case report of two patients who experienced episodes of heart transplant rejection when taking cyclosporine and St. John's wort. Cyclosporine levels were significantly lower during use of St. John's wort; when the herbal treatment was discontinued, cyclosporine levels returned to therapeutic range.

Herbs that increase bleeding time (such as ginkgo, feverfew, garlic, ginger, and ginseng) should be administered with caution when using anticoagulant therapies. Ginseng use may cause additive effects with estrogens or corticosteroids. Valerian should not be used with sedatives such as barbituates because of a risk of excessive sedation. Oils of evening primrose (Oenothera biennis) and borage (Borago officinalis) may reduce seizure thresholds and should not be given with anticonvulsants. Echinacea should not be administered in conjunction with immunosuppressants (e.g., cyclosporine) (Miller 1998).

Traditional uses of herbs are often confirmed by research; however, pharmacological analysis of active constituents is complicated by the fact that active plant ingredients are often multi-chemical in nature, and herbal treatments may be given in combinations for which the biomolecular interactions are unknown (Barrett et al. 1999). These challenges are illustrated by studies of two traditional menopause remedies: black cohosh (Cimicifuga racemosa) and dong quai (Angelica sinensis). Studies have indicated that black cohosh, through the synergistic effect of at least three compounds, selectively suppresses luteinizing hormone (LH) secretions with no effect on follicular stimulating hormone (FSH) (Duker et al. 1991). Animal studies of black cohosh demonstrate no estrogenic activity. Black cohosh is now thought to modulate the pituitary and LH release, thereby decreasing the fluctuations in the levels of endogenous estrogen rather than influencing the actual level of estrogen (Einer-Jensen et al. 1996). Dong quai has been used extensively in Traditional Chinese Medicine for treatment of menstrual and menopausal discomfort. A double-blind, randomized, placebo-controlled clinical trial evaluating the estrogenic effects of dong quai in post-menopausal women found no statistically significant differences in menopausal outcomes between dong quai and placebo groups. Because dong quai is typically used in combination with synergistic herbs in Traditional Chinese Medicine, the investigators conceded that additional studies need to be done on this important herb (Hirata et al. 1997).

Very few studies have been performed evaluating the efficacy of herbalism as it is generally practiced, i.e., administering combinations of herbs rather than a single herb or active agent (Vickers and Zollman 1999).

As herbal medicine becomes more mainstream, there is an urgent need for a thorough understanding of its applications and contraindications. The German Commission E, established in 1978, compiled over 300 monographs on the most commonly prescribed phytomedicines, based on pharmacological information and clinical evidence. These monographs summarize available data and provide guidelines on dosing and efficacy. An expanded American version of the Commission E monographs, published in 2000, includes over 100 of the most commonly prescribed herbs in the United States along with drug interactions and potential hazards (Blumenthal et al. 2000).

While there is a movement to analyze herbs and conduct research regarding the efficacy and safety of phytomedicines, the appropriate regulation of those herbs in the United States has fallen far behind. Until the passage of the Dietary Supplement Health and Education Act (DSHEA) of 1994, the FDA had not permitted the labeling and packaging of herbs to include information on dosage or indication. DSHEA reclassified herbs as dietary supplements that may be marketed with suggested dosages and statements about the product's probable physiologic effects. Although a step in the right direction, DSHEA falls short in several areas: no premarket testing for safety or efficacy is required, manufacturing need not be standardized, no direct claims regarding specific diseases or conditions may be made, and FDA approval is not required. While DSHEA protected the legal status of over-the-counter herbal products, it has done little to dispel the confusion and misinformation around herbal use, safety, and efficacy (D'Epiro 1999).

There are numerous classifications of herbalists, including professional herbalists (who learn their trade through formalized education or apprenticeship) and lay herbalists. Still others learn herbal medicine through traditional medical systems, such as Ayurvedic medicine, Traditional Chinese Medicine, and naturopathic medicine (Meserole 1996). Medical herbalists in the United Kingdom complete a four-year program and receive at least 500 hours of supervised clinical practice and training in nutrition, pharmacology, pharmacognosy, botany, and basic sciences. Upon completion of the program, graduates receive a B.Sc. degree in herbal medicine and become members of the National Institute of Medical Herbalists (NIMH) (Vickers and Zollman 1999).

For additional information regarding phytomedicine research, the following resources are available:

Blumenthal M, Busse WR, Goldberg A, et al., eds. The Complete German Commission E Monographs. Boston, Mass: Integrative Medicine Communications; 1998.

Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, Mass: Integrative Medicine Communications; 2000.

World Health Organization (WHO). WHO Monographs on Selected Medicinal Plants, Vol. 1. Geneva: World Health Organization; 1999.

The American Botanical Council: www.herbalgram.org/.

The National Center for Complementary and Alternative Therapy: www.nccam.org/.

Phytochemical and Ethnobotanical Databases: www.ars-grin.gov/duke/.

Barrett B, Kiefer D, Rabago D. Assessing the risks and benefits of herbal medicine: an overview of scientific evidence. Altern Ther Health Med. 1999;5(4):40-49.

Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, Mass: Integrative Medicine Communications; 2000.

Braunig B, Dorn G, Knick EM. Echinacea purpurea radix for strengthening immune response in flu-like infections [in German]. Z Phytother. 1993;13:7-13.

Brenner R, Azbel V, Madhusoodanan S, Pawlowska M. Comparison of an extract of Hypericum (LI 160) and sertraline in the treatment of depression: a double-blind, randomized pilot study. Clin Ther. 2000;22(4):411-419.

Chavez ML, Chavez PI. Herbal medicine. In: Novey DW, ed. Clinician's Complete Reference to Complementary and Alternative Medicine. St. Louis, Mo: Mosby; 2000:545-563.

D'Epiro NW. An historical, regulatory, and medical use perspective on nine common herbs. In: Micozzi MS, Bacchus AN, eds. The Physician's Guide to Alternative Medicine. Atlanta, Ga: American Health Consultants; 1999:21-30.

Donath F, Quispe S, Diefenbach K, Maurer A, Fietze I, Roots I. Critical evaluation of the effect of valerian extract on sleep structure and sleep quality. Pharmacopsychiatry. 2000;33(2):47-53.

Duker E, Kopanski L, Jarry H, Wuttke W. Effects of extracts from Cimicifuga racemosa on gonadotropin release in menopausal women and ovariectomized rats. Planta Med. 1991;57(5):420-424.

Einer-Jensen N, Zhao J, Andersen KP, Kristoffersen K. Cimicifuga and Melbrosia lack oestrogenic effects in mice and rats. Maturitas. 1996;25(2):149-153.

Ernst E. Herbal medications for common ailments in the elderly. Drugs Aging. 1999;15(6):423-428.

Hirata JD, Swiersz LM, Zell B, Small R, Ettinger B. Does dong quai have estrogenic effects in postmenopausal women? A double-blind, placebo-controlled trial. Fertil Steril. 1997;68(6):981-986.

Le Bars PL, Katz MM, Berman N, Itil TM, Freedman AM, Schatzberg AF. A placebo-controlled, double-blind, randomized trial of an extract of Ginkgo biloba for dementia. North American EGb Study Group. JAMA. 1997:278(16):1327-1332.

Linde K, Mulrow CD. St. John's wort for depression (Cochrane Review). In: The Cochrane Library, Issue 3, 2000. Oxford: Update Software.

McIntyre M. A review of the benefits, adverse events, drug interactions, and safety of St. John's wort (Hypericum perforatum): the implications with regard to the regulation of herbal medicines. J Altern Complement Med. 2000;6(2):115-124.

Meserole L. Western herbalism. In: Micozzi MS, ed. Fundamentals of Complementary and Alternative Medicine. New York, NY: Churchill Livingstone; 1996:111-120.

Miller LG. Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions. Arch Intern Med. 1998;158(20):2200-2211.

Schoeneberger D. The influence of immune-stimulating effects of pressed juice from Echinacea purpurea on the course and severity of colds [in German]. Forum Immunologie. 1992;8:2-12.

Vickers A, Zollman C. Herbal medicine. BMJ. 1999;319(7216):1050-1053.

Volz HP, Kieser M. Kava-kava extract WS 1490 versus placebo in anxiety disorders—a randomized placebo-controlled 25-week outpatient trial. Pharmacopsychiatry. 1997;30(1):1-5.

Woelk H, Burkard G, Grunwald J. Benefits and risks of the Hypericum extract LI 160: drug monitoring study with 3250 patients. J Geriatr Psychiatry Neurol. 1994;7(suppl 1):S34-38.

Woelk H, Kapoula O, Lehrl S, et al. Treatment of anxiety patients. Kava special extract WS 1490 in anxiety patients is comparable to the benzodiazepine oxazepam, a double-blind study [in German]. Z Allgemeinmed. 1993;69:271-277.