Herbs & Botanicals
Psoralea (bu gu zhi)
What is psoralea? What is it used for?
Psoralea is an annual herb native to west Asia, although it also found in China and Vietnam. The plant grows to a height of about two feet, and requires moist soil to prosper. The seeds are used medicinally; they are typically harvested in the fall while ripe, then dried in the sun. They are either left raw or are stir-baked with salt water before being incorporated into herbal remedies.
Psoralea seeds contain a variety of amino acids and other substances, including flavonoids, coumarins, linoleic acid and oleic acid, and small amounts of potassium, calcium, iron and selenium.
Psoralea is associated with the Kidney and Spleen meridians, and is considered to have bitter, pungent and hot properties, according to traditional Chinese medicine principles. It is used to tonify the kidneys and to tonify and strengthen the spleen.
Psoralea can be used to treat a variety of conditions. It is considered an excellent tonic herb, and is used to improve general vitality. Internally, it can clear up cases of diarrhea, and reduce pain in the lower back. It is also employed to treat several urogenital conditions, such as frequent urination, incontinence and bed-wetting. Topically, it can help treat alopecia and some skin lesions, such as psoriasis.
How much psoralea should I take?
The recommended daily dose of psoralea is 3 to 9 grams, usually taken as a decoction. Some practitioners may recommend a slightly higher dose (5-10 grams). The dosage can be even higher if psoralea is being applied topically.
What forms of psoralea are available?
Dried psoralea fruit or seeds can be found at some Asian markets and herbal shops. Powdered psoralea is also commonly available, and is used to make herbal decoctions.
What can happen if I take too much psoralea? Are there any interactions I should be aware of? What precautions should I take?
Psoralea should not be used by patients who have yin deficiency, or who present with constipation. In addition, while there are no known incidents of toxicity from taking large doses of psoralea, some varieties contain substances called furanocoumarins, which can cause photosensitivity in some individuals. Psoralea contains another substance called psoralen, which can cause the skin to produce new pigment when the skin is exposed to sunlight. Some caution should also be employed by people who are sensitive to sunlight or who sunburn easily, as psoralea, when applied to the skin, can cause an allergic reaction. As always, make sure to consult with a licensed health care provider before taking psoralea or any other herbal remedy or dietary supplement.
- Editorial Committee of Chinese Materia Medica, State Drug Administration of China. Chinese Materia Medica. Shanghai: Science and Technology Press, 1998.
- Mi SQ, et al. Journal of New Chinese Medicine and Clinical Pharmacology 1998;9(1):27-29.
- Wu SH, et al. China Journal of Chinese Medicine 1998;23(5):303-305.
- Hu Y, et al. China Journal of Traditional Chinese Medicine Science and Technology 1999;6(3):157-158.
- Lei TC, et al. China Journal of Dermatology 1999;3(2):115-118.