AstragalusBotanical

• Blood sugar, as an add-on to metforminPossibly helps

  A 2024 review of 20 studies in 953 adults with type 2 diabetes found astragalus added to metformin lowered fasting blood glucose and HbA1c more than metformin alone [1].
  
  NCCIH's own summary notes most of the included studies were low quality or biased [1]. ^[1]

• Immune markersPossibly helps

  A 2023 review of 19 studies in 1,094 participants reported enhanced immune responses and reduced proinflammatory cytokines [1].
  
  The underlying studies were small and heterogeneous, which is why NCCIH stops short of calling the effect useful [1]. ^[1]

• Membranous nephropathy (a kidney disorder)Possibly helps

  A 2023 review of 50 studies in 3,423 participants found astragalus, added to standard or immunosuppressive therapy, improved some kidney-health indicators more than that therapy alone [1].
  
  A 2011 meta-analysis indexed in the NIH's DARE database reported a similar renal signal in diabetic nephropathy [6].
  
  Both are add-on findings in already-diseased kidneys. Neither says anything about healthy ones. ^[1]

• Cancer-related fatigue and quality of lifePossibly helps

  A 2025 systematic review and meta-analysis of 8 randomized trials found reduced cancer-related fatigue, at SMD -1.63 (95% CI -1.90 to -1.36, P<.00001) [5].
  
  Quality of life improved as well, SMD 0.86 (95% CI 0.17 to 1.55, P=.01) [5].
  
  The authors' own conclusion is that sample sizes and study quality are too weak to strongly support clinical use [5]. ^[5]

• The disagreement itself, kept visiblePossibly helps

  NCCIH says there is not enough reliable evidence to know whether astragalus is useful for any health condition [1].
  
  The systematic reviews it summarizes report statistically significant benefits anyway, driven by low-quality studies — which is precisely NCCIH's point [1].
  
  Merck Manual goes further, saying no health benefit has been confirmed in high-quality human studies for any claimed use, with most trials under 150 participants [4].
  
  All three framings stay on this page rather than being averaged into one tidy verdict. ^[1]

• Injectable evidence does not transfer to capsulesPossibly helps

  Most of the stronger cancer-supportive-care evidence — less nausea and vomiting, better quality of life, immune-profile support during chemotherapy — comes from injectable astragalus used in China [3].
  
  That form is not sold in the US, and whether oral capsules or decoctions do the same thing is stated as unknown by MSKCC and the ASCO Post [3]. ^[3]

• COVID-19Possibly helps

  Astragalus was widely promoted against COVID-19 through 2020 and 2021 [1].
  
  Both NCCIH and Merck Manual flag that no evidence supported that specific use, then or since [4]. ^[1]

• Dried root slices, for decoctionTraditional Chinese Medicine tonic use.

  Elemental content

  Whole dried root, not standardized to any marker compound [2]

  Absorption

  Health Canada's direction is to submerge the root fully in water, boil 20-25 minutes, strain, and drink. A Journal of Functional Foods review describes a soup version: soak in water about 60 minutes, then boil 20-25 minutes, then remove the root pieces [13]

  Best for

  Traditional Chinese Medicine tonic use. This is the only preparation Health Canada permits at the 9-30 g/day range [2]

• Powdered root, capsules and tabletsThe immune-maintenance and adaptogen label claims, where Health Canada's range drops to 2-4.

  Elemental content

  Dry or powdered root, non-standardized [2]

  Absorption

  Reported at 250-500 mg four times a day in a Journal of Functional Foods review [13]

  Best for

  The immune-maintenance and adaptogen label claims, where Health Canada's range drops to 2-4.8 g/day [2]

• Tinctures and fluid extractsPeople who want a measured dose without boiling root for half an hour

  Elemental content

  Non-standardized extract — Health Canada permits only ethanol and/or water as extraction solvents for the dry-extract form [2]

  Absorption

  Taken as drops; a 1:2 liquid extract is reported at 4-8 mL/day [13]

  Best for

  People who want a measured dose without boiling root for half an hour [13]

• Injectable preparationsNothing you can buy here — not available in the US, per MSKCC and Merck Manual, yet it produced most of the stronger ca…

  Elemental content

  A clinical preparation, not a consumer supplement

  Absorption

  Given by injection in Chinese hospital practice, including the cancer-supportive-care trials [3]

  Best for

  Nothing you can buy here — not available in the US, per MSKCC and Merck Manual, yet it produced most of the stronger cancer-care evidence [3]

• Reported side effects

  The reported effects are generally minor: rash, itching, runny nose, nausea, diarrhea, and headache [1].
  
  MSKCC also lists low blood pressure, lasting only 24 hours, among side effects reported in a study [3]. ^[1]

• Autoimmune disease

  Because astragalus may increase immune-system activity, NCCIH and Health Canada both advise people with lupus, rheumatoid arthritis, or multiple sclerosis to avoid it or ask a health care provider first [1]. ^[1]

• Pregnancy and breastfeeding

  NCCIH says little is known about safety here, and notes some animal research suggesting astragalus can be toxic to the fetus [1].
  
  Health Canada requires a practitioner-warning statement on products, and Merck Manual lists pregnancy among the reasons to avoid it [4]. ^[1]

• Children

  Health Canada's monograph doses are written for adults 18 and over only [2].
  
  Merck Manual lists children among the groups who should avoid astragalus, citing insufficient research in that age group [4]. ^[2]

• Tacrolimus and cyclosporine

  Because astragalus may stimulate immune activity, it may work against immunosuppressant drugs [3].
  
  MSKCC cites a case report in refractory nephrotic syndrome where astragalus-containing herbal granules taken alongside tacrolimus coincided with a nearly 50% drop in tacrolimus blood concentration [3]. ^[3]

• Warfarin and other anticoagulants

  Astragalus and its constituents show anticoagulant properties in laboratory studies, so bleeding risk may rise alongside warfarin [3].
  
  Clinical significance in people has not been established [3]. ^[3]

• Blood pressure medication

  An astragalus extract lowered both systolic and diastolic blood pressure in a study of healthy adults [12].
  
  Stacked on an antihypertensive, that effect may add up and push blood pressure lower than intended [3]. ^[12]

• Diuretics

  A small study in healthy men found astragalus has natriuretic effects, meaning it increases sodium excretion [3].
  
  That may be additive with diuretic drugs [3]. ^[3]

• Diabetes medication

  Astragalus may lower blood glucose on its own, so Merck Manual and WebMD both flag possible hypoglycemia alongside antidiabetic drugs [4].
  
  That fits the separate finding that astragalus added to metformin lowered fasting glucose and HbA1c further than metformin alone [8]. ^[4]

• Lithium

  Merck Manual states astragalus might impair the body's ability to clear lithium, risking a dangerous build-up in anyone taking both [4]. ^[4]

• Hormone-suppressing cancer therapy

  Astragalus and constituents such as formononetin show estrogenic activity in laboratory work, so they may interfere with hormone-suppressing treatments [3].
  
  Clinical relevance in people is not known [3]. ^[3]

• Chemotherapy agents

  Astragalus polysaccharides inhibit P-glycoprotein efflux pump function in preclinical studies, which could raise the cytotoxicity of doxorubicin, etoposide, and vincristine [3].
  
  Pretreatment with an astragalus extract also altered gemcitabine pharmacokinetics in a mouse model. Human relevance is unknown [3]. ^[3]

Not applicable in the usual sense. Astragalus root is the ingredient itself, not a nutrient you pick up incidentally from other foods [13].

It does get eaten in food form — simmered into soups and broths, or drunk as a tea [13].

The woody root is strained out and discarded rather than chewed [13].

No monograph or trial reviewed here names a time of day, or settles whether to take astragalus with food or without [2].

Health Canada's only preparation direction is the decoction method: boil the dried or powdered root, fully submerged, for 20-25 minutes, then strain and drink [2].

Traditional use is as an ongoing daily tonic over weeks to months, not something dosed for an acute, time-sensitive effect [1].

No trial comparing morning against evening, or empty stomach against with food, turned up in government, academic, or medically-reviewed sources. That is a genuine gap, reported rather than papered over [1].