Corydalis

Description

Corydalis is the name of a group of herbs used in different parts of the world to relieve pain . Corydalis yanhusuo is a species used primarily in Chinese herbal medicine. C. gariana, native to the Himalayas, is used medicinally in India. A related species, Corydalis cava, is used in European herbalism. Another closely related species, is Corydalis canadensis (also called Dicentra canadensis ) and known by the common name corydalis or turkey corn, is found in North America. There are other species of Corydalis found throughout the world. Although the names are somewhat confusing, many are used by herbal therapists in similar ways and are included under the umbrella label corydalis.

C. yanhusuo is a small herb that grows in mixed sun and shade at the edge of woodlands. It is native to Siberia, northern China, and Japan, but is cultivated in other cool parts of China. C. yanhusuo grows to about 8 in (20 cm) in height and has narrow leaves and pink flowers. The rhizome (underground stem) is used in healing. C. yanhusuo is called yan hu suo in Chinese. Some sources suggest that C. yanhusuo is used interchangeably with the related species C. solida, which is called by the same Chinese name.

C. cava is a perennial that grows in shady forests. It is native to southern Europe and has spread throughout the continent. C. cava grows to a height of about 11 in (30 cm). Its flowers range in color from red to yellowish to white, with occasional lilac, brownish-red, or dark blue flowers. The tubers (knobby, fleshy underground stems) are used medicinally. Alternative names for the North American species of corydalis include turkey corn, squirrel corn, and early fumitory.

General use

In traditional Chinese medicine (TCM), C. yanhusuo is said to have a warm nature and a pungent, bitter taste. It is associated with the heart, liver, and spleen. C. yanhusuo is used to relieve pain resulting from almost any cause. It is especially used to treat menstrual cramps, chest pains, and abdominal pain. Corydalis is also the preferred herb in treating pain from traumatic injuries. Some herbalists report that frying corydalis in vinegar enhances its ability to ease pain.

Along with its ability to relieve pain, C. yanhusuo is used as a general aid to blood circulation and to promote the circulation of qi, or vital energy. Some Chinese herbalists also report using corydalis as a sedative and to lower blood pressure. The herb is frequently found in combination with other plants in Chinese formulas that treat stabbing pain sensations, painful periods, and the like.

In Western medicine, the various corydalis species are used to treat shaking and involuntary tremors . They can be used to treat people with Parkinson's disease . Corydalis is also used as a painkiller; a diuretic; a sedative that slows the pulse and depresses the central nervous system; and a tonic that invigorates the circulation. Occasionally it is used to treat mild forms of depression . In fact, the uses of the various corydalis species are surprisingly similar around the world.

Research scientists have isolated several potent alkaloid compounds from corydalis. The strongest of these is corydaline. It has the ability to block certain receptors in the brain associated with the sensation of pain. There is good evidence from Chinese studies that corydalis is effective in relieving pain and menstrual cramps. Evidence for the other uses of corydalis is limited to test tube and animal studies. One 1999 study at the University of Maryland Dental School found that an extract of C. yanhusuo was successful in reducing artificially induced inflammation in the paws of rats, although it was less successful than some other TCM herbs that were tested.

Preparations

Corydalis tubers and rhizomes are dug either in the spring or fall, before or after the leaves are actively growing. They are dried and kept in a cool place before use. Corydalis can be made into a tea, a tincture, or a decoction. Commercial extracts are also available.

Corydalis is usually combined with other herbs. One popular treatment for menstrual pain is a decoction of corydalis and cinnamon. In traditional Chinese medicine, corydalis is found in almost all formulas to treat menstrual pain, other pain formulas, and formulas to improve the circulation.

Precautions

Chinese herbalists report that pregnant women should not take corydalis. Since corydalis contains a compound that depresses the central nervous system, it should be used cautiously when using other central nervous system depressant drugs or alcohol. This herb should be taken under the supervision of a trained herbalist.

Side effects

Although no poisonings from corydalis have been reported, overdose is likely to produce shaking and tremors.

Interactions

Some Western herbalists report that corydalis is incompatible with tannic acid and vegetable astringents. Corydalis has been used in many Asian formulas without any reported interactions. Few, if any, scientific studies have been done on its interactions with Western pharmaceuticals.