Phytotherapy is the study of the use of extracts from natural origin as medicines or health-promoting agents.

Traditional phytotherapy is often used as synonym for herbalism

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, medical herbalism, herbal medicine, herbology, herblore, and phytotherapy...

 and regarded as "alternative medicine

Alternative medicine

Alternative medicine is any healing practice, "that does not fall within the realm of conventional medicine." It is based on historical or cultural traditions, rather than on scientific evidence....

" by much of Western medicine, although effects of many substances found in plants have scientific evidence.

Modern phytotherapy when critically conducted, can be considered the scientific study on the effects and clinical use of herbal medicines.

Standardization

In herbal medicine, standardization refers to providing processed plant material that meets a specified concentration of a specific marker constituent. Active constituent concentrations may be misleading measures of potency if cofactors

Cofactor (biochemistry)

A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....

 are not present. A further problem is that the important constituent is often unknown. For instance St John's wort

St John's wort

St John's wort is the plant species Hypericum perforatum, and is also known as Tipton's Weed, Chase-devil, or Klamath weed....

 is often standardized to the antiviral constituent hypericin

Hypericin

Hypericin is a naphthodianthrone, a red-colored anthraquinone-derivative, which, together with hyperforin, is one of the principal active constituents of Hypericum . Hypericin is believed to act as an antibiotic and non-specific kinase inhibitor...

 which is now known to be the active ingredient

Active ingredient

An active ingredient is the substance of a pharmaceutical drug or a pharmaceutical ingredient and bulk active in medicine; in pesticide formulations active substance may be used. Some medications and pesticide products may contain more than one active ingredient...

 for antidepressant use. Other companies standardize to hyperforin

Hyperforin

Hyperforin is a phytochemical produced by some of the members of the plant genus Hypericum, notably Hypericum perforatum .- Occurrence :...

 or both, although there may be some 24 known possible constituents. Only a minority of chemicals used as standardization markers are known to be active constituents. Standardization has not been standardized yet: different companies use different markers, or different levels of the same markers, or different methods of testing for marker compounds. Herbalist and manufacturer David Winston

David Winston

David Winston RH is an American herbalist and ethnobotanist. He has been in practice and teaching since 1977 and has written several books on the subject. He works in the Cherokee, Chinese and the Western eclectic herbal traditions...

 points out that whenever different compounds are chosen as 'active ingredients' for different herbs, there is a chance that suppliers will get a substandard batch (low on the chemical markers) and mix it with a batch higher in the desired marker to compensate for the difference.

Quality

The quality of crude drugs or plant medicines depends upon a variety of factors, including the variability in the specie (or species) of plant being used; the plant's growing conditions (i.e. soil, sun, climate); and the timing of harvest, post-harvest processing, and storage conditions. The quality of some plant drugs can judged by Organoleptic

Organoleptic

Organoleptic is an adjective used to refer to the aspects of food or other substances as experienced by the senses, including taste, sight, smell, and touch.-USDA uses:...

 factors (i.e. sensory properties such as the taste, color, odor or
feel of the drug), or by administering a small dose of the drug and observing the effects.

These conditions have been noted in historical herbals such as Culpepper's Complete Herbal or The Shen Nong or Divine Farmer's Materia Medica. This was standard pharmacognosy curriculum for many years.

Storage after collection is a factor worthy of study; researchers in Nara, Japan have stored samples of ginseng root (Panax ginseng), licorice root (Glycyrrhiza glabra) and rhubarb root (Rheum emodi

Rheum emodi

Rheum emodi, commonly known as Himalayan rhubarb, is a medicinal herb used in the Indian Ayurvedic system of medicine. It belongs to the family Polygonaceae...

) that have been shown to retain their active properties for over 1,200 years.

In modern times the foregoing aspects are no less important, but have been neglected with the advent of laboratory testing, although it generally is true that only certain constituents are identified and measured. Processes like HPLC

High-performance liquid chromatography

High-performance liquid chromatography , HPLC, is a chromatographic technique that can separate a mixture of compounds and is used in biochemistry and analytical chemistry to identify, quantify and purify the individual components of the mixture.HPLC typically utilizes different types of stationary...

 (High performance liquid chromatography), GC (gas chromatography), UV/VIS (Ultraviolet/Visible spectrophotometry

Spectrophotometry

In chemistry, spectrophotometry is the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength...

) or AA (atomic absorption spectroscopy)are used to identify species, measure bacteriological contamination, assess potency and eventually creating Certificates of Analysis for the material.

Quality should be overseen by either authorities ensuring Good Manufacturing Practices or regulatory agencies by the US FDA. In the United States one frequently sees comments that herbal medicine is unregulated, but this is not correct since the FDA and GMP regulations are in place. In Germany, the Commission E

Commission E

The German Commission E Monographs are a therapeutic guide to herbal medicine with 380 monographs evaluating the safety and efficacy of herbs for licensed medical prescribing in Germany. The commission itself was formed in 1978, and no longer exists....

 has produced a book of German legal-medical regulations which includes quality standards.

Safety

A number of herbs are thought to be likely to cause adverse effects. Such herbs, like most herbs for example in Traditional Chinese Medicine

Traditional Chinese medicine

Traditional Chinese Medicine refers to a broad range of medicine practices sharing common theoretical concepts which have been developed in China and are based on a tradition of more than 2,000 years, including various forms of herbal medicine, acupuncture, massage , exercise , and dietary therapy...

, are used in small doses within the herbal formula.

Furthermore, "adulteration, inappropriate formulation, or lack of understanding of plant and drug interactions have led to adverse reactions that are sometimes life threatening or lethal." Proper double-blind clinical trials are needed to determine the safety and efficacy of each plant before they can be recommended for medical use. Although many consumers believe that herbal medicines are safe because they are "natural", herbal medicines may interact with synthetic drugs causing toxicity to the patient, may have contamination that is a safety consideration, and herbal medicines, without proven efficacy, may be used to replace medicines that have a proven efficacy.

The political issues around the safety of crude drugs vary from considering natural remedies "safe" regardless of potential dangers to considering them a dangerous unknown.

Ephedra

Ephedra

Ephedra refers to the plant Ephedra sinica. E. sinica, known in Chinese as ma huang , has been used in traditional Chinese medicine for 5,000 years for the treatment of asthma and hay fever, as well as for the common cold...

 has been known to have numerous side effects, including severe skin reactions, irritability, nervousness, dizziness, trembling, headache

Headache

A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...

, insomnia

Insomnia

Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...

, profuse perspiration, dehydration

Dehydration

In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...

, itchy scalp and skin, vomiting, hyperthermia

Hyperthermia

Hyperthermia is an elevated body temperature due to failed thermoregulation. Hyperthermia occurs when the body produces or absorbs more heat than it can dissipate...

, irregular heartbeat, seizure

Seizure

An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...

s, heart attack

Myocardial infarction

Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...

, stroke

Stroke

A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

, or death

Death

Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

.

There is no evidence to conclude that herbs have more side effects and adverse actions than western (chemically synthesized) medications, which routinely have the same adverse side effects declared on their packages.

Poisonous plants which have limited medicinal effects are often not sold in material doses in the United States or are available only to trained practitioners, these include:

• Aconite
  Aconitum napellus
  Aconitum napellus is a species of Aconitum in the family Ranunculaceae, native and endemic to western and central Europe....
  
  
• Arnica
  Arnica montana
  Arnica montana, known commonly as leopard's bane, wolf's bane, mountain tobacco and mountain arnica, is a European flowering plant with large yellow capitula....
  
  
• Belladonna
• Bryonia
  Bryonia dioica
  Bryonia dioica, known by the common names red bryony and white bryony, is a perennial climbing vine indigenous to Central and Southern Europe. It is a flowering plant of the genus Bryonia with five-pointed leaves and blue or white flowers. The vine produces a red berry fruit.-Medicinal use:A...
  
  
• Datura
• Gelsemium
  Gelsemium
  Gelsemium is a genus of flowering plants belonging to family Gelsemiaceae. The genus contains three species of shrubs to straggling or twining climbers. Two species are native to North America, and one to China and Southeast Asia....
  
  
• Henbane
• Male Fern
• Phytolacca
• Podophyllum
• Veratrum
  Veratrum nigrum
  Veratrum nigrum is a coarse, highly poisonous perennial herb of the Melanthiaceae family. As is indicated by its name, the plant is not a hellebore , but from a closely related genus, Veratrum. The plant was widely known even in ancient times. For example, Lucretius Veratrum nigrum (or Black False...
  
  

Furthermore, herbs such as Lobelia

Lobelia

Lobelia is a genus of flowering plant comprising 360–400 species, with a subcosmopolitan distribution primarily in tropical to warm temperate regions of the world, a few species extending into cooler temperate regions...

, Ephedra

Ephedra

Ephedra refers to the plant Ephedra sinica. E. sinica, known in Chinese as ma huang , has been used in traditional Chinese medicine for 5,000 years for the treatment of asthma and hay fever, as well as for the common cold...

 and Eonymus

Euonymus

Euonymus , often called spindle or spindle tree, is a genus of flowering plants in the staff vine family, Celastraceae. It comprises about 170–180 species of deciduous and evergreen shrubs and small trees...

 that cause nausea, sweating, and vomiting, have been traditionally prized for this action.

Plants such as Comfrey

Comfrey

Comfrey is an important herb in organic gardening. It is used as a fertilizer and also has many purported medicinal uses...

 and Petasites have specific toxicity due to hepatotoxic pyrrolizidine alkaloid content. There are other plant medicines which require caution or can interact with other medications, including St. John's wort and grapefruit

Grapefruit

The grapefruit , is a subtropical citrus tree known for its sour fruit, an 18th-century hybrid first bred in Barbados. When found, it was named the "forbidden fruit"; it has also been misidentified with the pomelo or shaddock , one of the parents of this hybrid, the other being sweet orange The...

.