MSD Manual

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Laura Shane-McWhorter

, PharmD, University of Utah College of Pharmacy

Reviewed/Revised Jan 2022 | Modified Sep 2022

What is astragalus?

Astragalus is a perennial plant that is native to China, Mongolia, and Korea.

Advocates believe that astragalus is an adaptogen Adaptogens "Adaptogen" is a term for certain foods and supplements that are said to help the body cope with "stress." Stress may be psychologic (in the mind), but also may be physical (in the body), and... read more . 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.

What claims are made about 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

Does astragalus work?

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.

The evidence from studies in people to show that astragalus has the claimed health benefits is limited. Most or all of these studies 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:

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.

What are the possible 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.

What drug interactions occur with astragalus?

  • Because astragalus can make the immune system more active, it might reduce the effects of drugs (such as tacrolimus and cyclosporine) that suppress immune system activity.

  • 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 drugs to lower their blood pressure.

  • Astragalus might increase the impact of diuretics (drugs to increase urine).

  • Astragalus might make it hard for the body to get rid of lithium, so dangerous levels of lithium could build up in people who take both astragalus and lithium.


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.

  • Women who are breastfeeding and people who take certain drugs (including drugs to suppress the immune system, hormonal treatments, anticoagulants, blood pressure drugs, lithium, and diuretics) should talk to their doctor before taking astragalus.

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