Astragalus

Astragalus is the common name for the root of Astragalus membranaceus, a perennial plant in the legume family (Fabaceae) native to temperate parts of Asia, including northern China, Mongolia, and Siberia. ^[1] Only the root, known in commerce as Astragali Radix or huang qi, is used medicinally; it is typically harvested from mature plants, dried, and sliced. Care is taken to distinguish the medicinal species from toxic members of the large Astragalus genus. ^[1]

The herb has been used for well over two thousand years in traditional Chinese medicine, where it is classed as a qi tonic intended to strengthen vitality and resistance to illness. ^[2] It is also counted among the fundamental herbs of traditional Mongolian medicine. Preparations range from sliced root added to soups and teas to concentrated extracts.

The root's activity is attributed to three main groups of compounds: triterpene saponins, most notably astragaloside IV; polysaccharides; and flavonoids such as calycosin and formononetin. ^[1][5] These constituents, especially the polysaccharides and saponins, are the focus of most pharmacological study. ^[1]

Modern interest centers on the immune system. A review of Astragali Radix concluded that it can enhance several arms of immune function, acting on immune organs, mucosal defenses, and both innate and adaptive immune cells, which has prompted interest in its use alongside conventional treatment. ^[1] An older review of tonic herbs similarly examined astragalus among agents studied for immune support in cancer care. ^[2] A controlled clinical trial reported that an astragalus extract eased symptoms of seasonal allergic rhinitis, though the supporting evidence overall is limited. ^[3]

Constituents of the plant have additionally been studied for antioxidant, anti-inflammatory, and neuroprotective activity in laboratory settings. ^[4] In Western countries astragalus is sold as a dietary supplement rather than an approved medicine, in the form of capsules, tinctures, teas, and dried root, and it is generally considered well tolerated in healthy adults.

Well tolerated for most people with few side effects. Because it stimulates immune function, those with autoimmune disease or on immunosuppressive drugs should be careful, and it may interact with some immune therapies. Long-term high-dose safety is reasonably established through traditional use.