Herbal remedies prepared by infusion, decoction, or alcohol tincture from the appropriate plant part, such as the leaf, root, or flower, are generally safe when ingested in properly designated therapeutic dosages. However, many herbs have specific contraindications for use when certain medical conditions are present. Not all herbal remedies may be safely administered to infants or small children. Many herbs are not safe for use by pregnant or lactating women. Some herbs are toxic, even deadly, in large amounts, and there is little research on the chronic toxicity that may result from prolonged use. Herbal remedies are sold in the United States as dietary supplements and are not regulated for content or efficacy. Self-diagnosis and treatment with botanical medicinals may be risky. A consultation with a clinical herbalist, naturopathic physician, or certified clinical herbalist is prudent before undertaking a course of treatment.
Essential oils are highly concentrated and should not be ingested as a general rule. They should also be diluted in water or in a non-toxic carrier oil before application to the skin to prevent contact dermatitis or photo-sensitization. The toxicity of the concentrated essential oil varies depending on the chemical constituents of the herb.
An American professor of pharmacognosy, Varro E. Tyler, believes that “herbal chaos” prevails in the United States with regard to herbs and phytomedicinals. In part he blames the herb producers and marketers of crude herbs and remedies for what he terms unproven hyperbole, poor quality control, deceptive labeling, resistance to standardization of dosage forms, and continued sale of herbs determined to be harmful.
A new warning about Western herbalism has been made necessary by technology. The Internet has a number of sites available with unregulated and often unhealthy advice about use of herbal remedies. Many herbalists and allopathic physicians urge patients to use caution when seeking Internet information on herbal treatments. One cancer-related study found that only 36% of the web sites found in a search offered information that complied with regulatory guidelines about unsubstantiated claims about treatment or cure of disease.