Astragalus is a perennial plant that is native to China, Mongolia, and Korea.
Advocates believe that astragalus is an adaptogen. This herbal medicine term means that this substance is thought to help the body respond to stress and restore normal function. In 2020 and 2021, many people have used astragalus to diminish the harmful effects of COVID-19 infection, although there is no evidence to support that use.
The roots of the astragalus plant have been used for centuries in combination with other herbs as part of traditional Chinese medicine.
Of the more than 2,000 species of astragalus, just 2 are typically used in dietary supplements: Astragalus membranaceus and Astragalus mongholicus.
Other names for astragalus include huáng qí and milkvetch.
Astragalus is available in liquid extracts, capsules, powders, and teas.
Astragalus contains antioxidants, which can potentially prevent cell damage.
(See also Overview of Dietary Supplements.)
Claims for Astragalus
The long list of health benefits claimed for this herb includes the following:
Boosts the immune system (although what this means or how this could be done is not clear)
Prevents cancer
Lowers blood pressure
Protects the liver and kidneys
Prevents and treats heart disease
Reduces nausea and vomiting caused by chemotherapy
Lowers blood sugar levels in people with diabetes
Prevents colds and other upper respiratory tract infections
Decreases fatigue
Astragalus is used topically to improve blood flow and speed wound healing.
Evidence for Astragalus
Any single compound, including astragalus, is highly unlikely to have such a broad range of health benefits. Thus, evidence is very unlikely to confirm such multiple benefits.
There are no high-quality studies in people demonstrating that astragalus is effective for treating any health condition. Most or all of the studies on astralagus are small (fewer than 150 participants) and of poor quality. These studies suggest that astragalus, often combined with standard treatment, could have the following benefits, among others:
Improve heart function in people with heart failure who are also treated with standard therapy (although some evidence does not confirm this benefit)
Control blood sugar levels in people with diabetes
Reduce signs of kidney damage in people with chronic kidney disease
Prevent infections in people with chronic hepatitis B
Reduce fatigue in athletes and people who have had a stroke
Injectable forms of astragalus might reduce symptoms and improve quality of life in people with cancer, but evidence is lacking to show that oral forms of the root offer the same benefits.
Larger, well-designed, and longer studies are needed to confirm any benefits of astragalus.
Side Effects of Astragalus
Most people tolerate astragalus well. But in rare cases, people in astragalus studies have developed minor side effects, including rashes, headache, fatigue, itching, runny nose, nausea, and diarrhea. Some astragalus species that are not included in commercial supplements may be toxic because they contain "swainsonine," an ingredient that is toxic to the nervous system. In animals, this ingredient has caused "locoweed" poisoning.
Not enough research has been done on the use of astragalus by pregnant and breastfeeding women or by children to tell whether this herb is safe for these groups.
If, as claimed, astragalus increases activity of the immune system, this could be a problem for people with an autoimmune disease, such as lupus, rheumatoid arthritis, or multiple sclerosis.
Drug Interactions with Astragalus
Astragalus and its components have similar effects to the hormone estrogen, so it could decrease effectiveness of cancer treatments designed to suppress estrogen.
Astragalus seems to prevent blood from clotting, so it could increase the risk of bleeding in people taking anticoagulants.
Astragalus might lower blood pressure too much in people taking medications to lower their blood pressure.
Astragalus might increase the impact of diuretics (medications to increase urine).
lithium could build up in people who take both astragalus and lithium.
Recommendations for Astragalus
No health benefits of astragalus have been confirmed in high-quality studies in people.
Use of astragalus is not recommended because there are no confirmed benefits to outweigh the possibility of negative side effects.
Astragalus seems to be safe for most people; however,
Pregnant women, children, people with autoimmune diseases, and those with liver disease should avoid astragalus.
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
National Institutes of Health's National Center for Complementary and Integrative Health: Astragalus
