Astragalus Root

📜 Historical Use

Astragalus is one of the older continuously used herbs in this database, and NCCIH's account of its history is short: the root has been used for centuries in traditional Chinese medicine, often in combination with other herbs. The name most readers meet on a label, Huang Qi, is one NCCIH lists among its common names, alongside milk vetch and the French astragale. NCCIH describes traditional Chinese medicine as a system that has evolved over thousands of years, whose practitioners use psychological and physical approaches such as acupuncture and tai chi as well as herbal products. Set that inheritance beside what astragalus is sold for today and the gap is wide. NCCIH lists the modern promoted uses as upper respiratory infections, allergic rhinitis, asthma, chronic fatigue syndrome, chronic kidney disease, diabetes, improving the immune response, and topical application for wound healing. Eight indications, not one of them supported by sufficient reliable evidence. The research that does exist has also not gone where the tradition points: the three reviews NCCIH cites concern type 2 diabetes, immune markers and membranous nephropathy, while the respiratory uses that dominate the marketing have produced nothing NCCIH judges worth summarising. That "often in combination with other herbs" detail quietly explains much of this - a herb used traditionally inside multi-herb formulas is hard to isolate and test alone, and NCCIH's verdict on Chinese herbal products generally is that many studies have been of poor quality. Centuries of use is a good reason to have studied astragalus. It is not a result.

📊 What the Research Shows

NCCIH's summary judgement on astragalus is the flattest of any substance covered on this site so far, and it belongs at the top: "There is not sufficient reliable scientific evidence to know whether astragalus is useful for any health condition." Not unclear, not promising - not sufficient, for anything. The three recent reviews NCCIH cites all point in a positive direction and are all undercut by their own quality. A 2024 review of 20 studies in 953 adults with type 2 diabetes found astragalus added to metformin reduced fasting blood glucose and HbA1C more than metformin alone; most of those studies were of low quality and found to have bias. A 2023 review of 19 studies in 1,094 participants found astragalus enhanced immune responses and reduced proinflammatory cytokines; the studies were small and differed widely in how they were done. A 2023 review of 50 studies in 3,423 participants found that adding astragalus to supportive care or immunosuppressive therapy for the kidney disorder membranous nephropathy improved some indicators of kidney health; its own authors cited low quality, small size and limited geographical location. Now the part that matters most for a page filed under immunity. Astragalus is promoted for upper respiratory infections, and NCCIH's dedicated review of colds and flu does not mention it once - not among the approaches with promise, not among those with conflicting evidence, not even in its list of things studied without enough evidence. That review's bottom line is that no complementary approach has been shown to be helpful for the flu. NCCIH's traditional Chinese medicine page arrives at the same place from the other direction: Chinese herbal products have been studied for respiratory diseases including the common cold, but because many studies have been of poor quality, no firm conclusions can be made.

Take 500-1000mg standardized extract daily. Or simmer dried root slices in soups and broths (traditional method).

Avoid during acute infections (may overstimulate). Not for use with immunosuppressant drugs.

⚠️ What happens if taken in excess:

Very safe when used appropriately. Excessive doses may overstimulate the immune system, worsening autoimmune conditions. Can interact with immunosuppressant drugs, reducing their effectiveness. Very high doses may lower blood pressure and blood sugar. Should be avoided during acute infections as it may interfere with immune response.

NCCIH names one interaction for astragalus and it is a drug class, not a vague caution: astragalus may interact with medications that suppress the immune system. The logic is visible on its face - a substance promoted to stimulate immune response, taken by someone whose treatment depends on suppressing it. That population is not hypothetical: the 2023 membranous nephropathy review NCCIH cites studied astragalus added to supportive care or immunosuppressive therapy, so the overlap is exactly where the evidence base sits. NCCIH names no individual immunosuppressant in its astragalus fact sheet. It does name drugs elsewhere, in its Know the Science module, where cyclosporine - used to prevent organ transplant rejection - appears on the short list with a "narrow therapeutic range", alongside carbamazepine, digoxin, phenytoin and warfarin; for those, an amount even a little too low or too high can cause reactions that are life-threatening or have life-altering outcomes. Joining those two statements is this page's inference, not NCCIH's, and it is flagged as such below. Second, surgery. NCCIH advises telling providers about all supplements as far in advance as possible, because they may affect the response to anesthetics or other perioperative medicines, may increase bleeding risk, or may cause serious changes in heart rate or blood pressure; some providers ask patients to stop all herbal supplements several weeks before elective surgery. Third, diabetes medication: the 2024 review reported its benefit with astragalus taken alongside metformin, so anyone already on a glucose-lowering drug who adds astragalus is stacking two things aimed at the same number. No cytochrome P450 enzyme, no drug transporter and no individually named drug appears for astragalus in any of the five sources read here. A page telling you astragalus inhibits CYP3A4 goes further than these federal sources do.

1. Astragalus: Usefulness and Safety — National Center for Complementary and Integrative Health NCCIH Herbs at a Glance (2025)[NIH ↗]
2. Colds, Flu, and Complementary Health Approaches: Usefulness and Safety — National Center for Complementary and Integrative Health NCCIH (2016)[NIH ↗]
3. Traditional Chinese Medicine: What You Need To Know — National Center for Complementary and Integrative Health NCCIH (2019)[NIH ↗]
4. Know the Science: How Medications and Supplements Can Interact — National Center for Complementary and Integrative Health NCCIH Know the Science (2026)[NIH ↗]