The root of the perennial astragalus plant is used as an antibacterial, anti-inflammatory and an antioxidant. It is commonly used in traditional Chinese medicine and is native to China, Mongolia and Korea. The root is usually harvested from plants that are four years old when the root is larger.
Dried astragalus root is prepared in different ways depending on the administration and purpose. It can be found powdered, as a tincture, in capsules or tablets and as a topical ointment. In some Asian countries, astragalus is found in injections that are given in medical or clinical settings.
Astragalus is classed in traditional Chinese medicine as an adaptoge, which means it helps the body counteract stress and disease. It has been used as an antibacterial and anti-inflammatory in topical treatments, and is taken to support the immune system, to prevent colds and other infections, to lower blood pressure, treat diabetes and strengthen liver function. It also is used as a mild diuretic and to support digestive function, relieving bloating, gas or diarrhea.
It is often used in combination with Echinacea, zinc and vitamin C as an herbal combination to fight colds during winter seasons, and is available as part of a cold prevention tea in herbal stores.
One U.S. study addressed the use of astragalus to boost immune system function in patients whose immune function had been destroyed as a result of chemotherapy or radiation. It appears to have some immune-boosting action, but the specifics have not been determined. A 2004 Chinese study showed that, in mice, compounds drawn from astragalus root transferred to cells that perform immune system functions, activating them and heightening the potential of immune response. Among herbs with a reputation for immune boosting effects, astragalus has been identified as a promising candidate for further study.
A 2000 study was among several that address astragalus's effects as an antioxidant. It found that compounds known to have antioxidant effects, including polysaccharides and flavonoids, are present in significant amounts in astragalus root. In 2009, astragalus was given to pregnant women with diabetes to test its antioxidant effectiveness in another Chinese study. The results were a lowering of blood glucose and an increase in antioxidant activity. It was thus recommended for further study to help treat and prevent gestational diabetes.
Astragalus is generally safe to use but is not recommended for those with a fever because it could prolong or strengthen the fever. The use of dried astragalus root has not been studied long-term or in widespread trials, and should always be approved by a doctor. Pregnant or breastfeeding women should avoid the use of astragalus and many other herbs and drugs. It also is known to negatively interact with immune-suppressing drugs such as those given to transplant patients, and also can produce a negative interaction with corticosteroids.