American ginseng
Summary
American ginseng is a different species from Asian Panax ginseng. A 4-month trial of a root extract cut colds per person, and a 364-person trial found less cancer-related fatigue at 8 weeks but not at the 4-week primary endpoint. It lowered warfarin's effect in a controlled trial, and several trials were run by makers.
Key facts
- In a randomised trial, American ginseng lowered peak INR and warfarin blood levels versus placebo in 20 healthy adults[6]
- A 400 mg/day extract for 4 months cut colds per person from 0.93 to 0.68; a review of 5 trials found shorter colds but no clear drop in how many people caught one[1][2]
- 2,000 mg/day: no significant difference at 4 weeks (primary endpoint, P = .07); fatigue improved more than placebo at 8 weeks (P = .003)[3]
- In 24 people with type 2 diabetes on usual medicines, 3 g/day lowered HbA1c by 0.29% and fasting glucose by 0.71 mmol/L versus placebo[4]
- The cold trial was funded by the extract's maker and two authors worked for it; the diabetes trial had a ginseng-company co-author; the cognition trial was co-run by the extract's supplier[1][4][5]
- 5 graded human outcomes on this page
- October 13, 2026
How it works
ProposedThe root contains ginsenosides and, in some extracts, poly-furanosyl-pyranosyl-saccharides that are proposed to modulate innate and acquired immune responses. How these translate into fewer colds or less fatigue in people is not established.[1][3]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Colds | Grade C | Mixed | Systematic review · n = 747 · 2011 | 2 rows |
| Fatigue | Grade C | Improved | RCT · n = 364 · 2013 | 1 row |
| Focus | Grade D | Improved | RCT · n = 61 · 2022 | 1 row |
| Blood sugar | Grade D | Improved | Crossover RCT · n = 24 · 2019 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Cold incidence and duration in healthy adults | Mixed | Grade C | Systematic review · n = 747 · 2011 Healthy adults in 5 trials, all of North American ginseng Form: North American ginseng root extract · Dose: Varied by trial (not pooled in the abstract) · Duration: 8-16 weeks Fewer colds overall in one trial (25%); the chance of catching at least one cold was not clearly lower (RR 0.70, 95% CI 0.48-1.02); colds were 6.2 days shorter in two trials. | 19592479 (opens PubMed)Source [2] |
| Cancer-related fatigue | Improved | Grade C | RCT · n = 364 · 2013 Fatigued cancer survivors at 40 US institutions Form: Wisconsin ginseng root (3% ginsenosides) · Dose: 2,000 mg/day · Duration: 8 weeks General fatigue improved 14.4 vs 8.2 points at 4 weeks (P = .07, primary endpoint not met) and 20 vs 10.3 points at 8 weeks (P = .003); toxicities did not differ from placebo. | 23853057 (opens PubMed)Source [3] |
| Number of laboratory-checked colds | Improved | Grade C | RCT · n = 279 · 2005 Adults aged 18-65 with at least 2 colds in the prior year (Edmonton, Canada; 323 randomised) Form: North American ginseng root extract rich in poly-furanosyl-pyranosyl-saccharides (CVT-E002) · Dose: 400 mg/day (2 x 200 mg) · Duration: 4 months Colds per person 0.68 vs 0.93 with placebo; 10.0% vs 22.8% had two or more colds; total symptom days 10.8 vs 16.5. | 16247099 (opens PubMed)Source [1] |
| Working memory and attention in young adults | Improved | Grade D | RCT · n = 61 · 2022 Healthy young adults (UK) Form: American ginseng extract (Cereboost) · Dose: Single doses, then daily dosing for 2 weeks (amount not stated in the abstract) · Duration: 2 weeks Working memory and attention improved after a dose, more so after 2 weeks of daily use; mental fatigue improved. | 34396468 (opens PubMed)Source [5] |
| HbA1c and fasting glucose in type 2 diabetes | Improved | Grade D | Crossover RCT · n = 24 · 2019 Adults with type 2 diabetes on conventional treatment (Toronto) Form: American ginseng extract · Dose: 3 g/day (1 g with each meal) · Duration: 8 weeks per arm HbA1c fell 0.29% and fasting glucose 0.71 mmol/L more than placebo; systolic blood pressure fell 5.6 mm Hg; liver and kidney safety tests unchanged. | 29478187 (opens PubMed)Source [4] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Standardised root extract | Varies[1][3] | No head-to-head human absorption data between extracts.[1][3] | Toxicities did not differ from placebo over 8 weeks at 2,000 mg/day; liver and kidney tests unchanged at 3 g/day.[3][4] | Cold trial (400 mg/day), fatigue trial (2,000 mg/day), diabetes trial (3 g/day) |
Studied doses
Doses studied in human trials ranged from 400 mg/day of a root extract for 4 months (colds) to 2,000 mg/day for 8 weeks (cancer-related fatigue) and 3 g/day for 8 weeks (type 2 diabetes).[1][3][4]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- WarfarinRCTAfter 2 weeks of American ginseng, peak INR fell by 0.19 and warfarin blood levels fell versus placebo in healthy volunteers, so warfarin may work less well.[6]
- Diabetes medicinesRCTAdded to usual diabetes treatment, 3 g/day lowered HbA1c and fasting glucose further, so glucose levels may need watching.[4]
Who should be careful
- People on warfarin
- American ginseng reduced warfarin's anticoagulant effect in a controlled trial.[6]
- People on glucose-lowering medicines
- It lowered HbA1c and fasting glucose on top of diabetes treatment.[4]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Safety first
Well tolerated in trials, but it interacts with warfarin.
How to read the label
Frequently asked questions
Is American ginseng the same as Korean or Asian ginseng?
No. American ginseng is Panax quinquefolius; Asian ginseng is Panax ginseng, with separate trials.[2]
Does American ginseng work for colds?
One 4-month trial of a specific extract cut colds per person; pooled trials showed shorter colds but no clear drop in catching one.[1][2]
Does it help cancer-related fatigue?
In a 364-person trial, 2,000 mg/day did not beat placebo at 4 weeks but did at 8 weeks.[3]
Can I take it with warfarin?
It lowered warfarin's effect in a controlled trial, so the combination needs medical oversight.[6]
Does it lower blood sugar?
In 24 people with type 2 diabetes, 3 g/day lowered HbA1c by 0.29% versus placebo.[4]
Sources
- [1]Efficacy of an extract of North American ginseng containing poly-furanosyl-pyranosyl-saccharides for preventing upper respiratory tract infections: a randomized controlled trial.. CMAJ, 2005. RCT
- [2]North American (Panax quinquefolius) and Asian Ginseng (Panax ginseng) Preparations for Prevention of the Common Cold in Healthy Adults: A Systematic Review.. Evid Based Complement Alternat Med, 2011. systematic-review
- [3]Wisconsin Ginseng (Panax quinquefolius) to improve cancer-related fatigue: a randomized, double-blind trial, N07C2.. J Natl Cancer Inst, 2013. RCT
- [4]Efficacy and safety of American ginseng (Panax quinquefolius L.) extract on glycemic control and cardiovascular risk factors in individuals with type 2 diabetes: a double-blind, randomized, cross-over clinical trial.. Eur J Nutr, 2019. crossover-RCT
- [5]A randomized, placebo-controlled trial investigating the acute and chronic benefits of American Ginseng (Cereboost®) on mood and cognition in healthy young adults, including in vitro investigation of gut microbiota changes as a possible mechanism of action.. Eur J Nutr, 2022. RCT
- [6]Brief communication: American ginseng reduces warfarin's effect in healthy patients: a randomized, controlled Trial.. Ann Intern Med, 2004. RCT
What changed
- Initial editorial evidence review: source titles and years taken from NCBI E-utilities esummary (no retraction or expression-of-concern flags), every evidence row, dose, n and duration read against the PubMed abstract or full text, funding and author affiliations checked where available, and grades held conservative.