Panax ginseng

Most ginseng trials are small: NCCIH notes that most clinical trials have had fewer than 200 participants and lasted less than 3 months [9]. A 2023 umbrella review of 19 meta-analyses rated 14 of them as critically low quality [15]. Our evidence grading method explains what each grade requires. Ginseng's grades sit alongside other compounds in the evidence matrix and on the memory, energy, physical performance and mood and stress hubs.

Does Panax ginseng improve memory?

A 2024 meta-analysis of 15 randomized controlled trials (671 participants) found a small improvement in memory compared with control (SMD = 0.19, 95% CI 0.02-0.36), larger at high doses (SMD = 0.33) [1]. The same analysis found no effect on overall cognition, attention or executive function, and it combined healthy people with groups who had cognitive impairment, schizophrenia or Alzheimer's disease, so it does not isolate healthy adults [1].

The Cochrane review, which searched the literature on February 24, 2009, identified nine randomized, double-blind, placebo-controlled trials, eight of them in healthy participants [2]. It could not pool the data because the trials differed in outcomes, duration and dose, and concluded there is a lack of convincing evidence of a cognitive-enhancing effect in healthy participants [2].

The healthy-adult trials are short crossover studies, in which each person takes every treatment in turn, using one branded extract, G115 [16][17][18]. In 20 healthy young adults given 200, 400 or 600 mg of G115 or placebo, 400 mg improved a "Quality of Memory" score at all test times [16]. The same trial found that 200 and 600 mg slowed a "Speed of Attention" score at later test times, and self-rated alertness fell 6 hours after the two lowest doses [16]. A review by the same research group described this pattern as memory benefits that can come with "costs" on attention tasks [19]. That trial tested G115, an extract supplied by Pharmaton SA [16].

NCCIH summarizes the cognitive research as suggesting possible benefits in middle-aged adults but not in young adults, and notes that memory benefits appeared to depend on adding ginkgo [9].

Does Panax ginseng reduce fatigue or mental tiredness?

Evidence is mixed. In a 2023 meta-analysis of 19 randomized trials, ginseng did not significantly reduce fatigue severity overall compared with controls (SMD = -0.36, 95% CI -0.82 to 0.11) [3]. In subgroups, it reduced general, non-disease-specific fatigue (SMD = -0.48, 95% CI -0.71 to -0.25), and the authors noted that effect sizes were small [3]. The review pooled single-herb ginseng with multi-herb ginseng formulas, and its authors credited the benefit mainly to the formulas [3]. NCCIH says Asian ginseng alone may have a small benefit for general fatigue not related to specific diseases [9].

An earlier meta-analysis found reduced fatigue in a fixed-effect analysis of four placebo-controlled trials (SMD = 0.34, 95% CI 0.16 to 0.52) [4]. Its authors still judged the clinical evidence insufficient, because only a few small trials had been published [4]. A systematic review of 10 studies of Asian and American ginseng in people with fatigue, mostly with chronic illness, found modest evidence of efficacy [12]; results may not apply to healthy adults.

In healthy young adults, the evidence is two small crossover trials of G115 during demanding mental tasks [18][20]. In 30 participants given single doses, 200 mg improved a subtraction task and reduced self-rated mental fatigue at most test points compared with placebo [18]. In 27 participants, 200 mg improved mental arithmetic and lessened the rise in mental fatigue during sustained tasks [20].

Does Panax ginseng improve exercise performance?

In controlled trials, no consistent benefit was detected [4][5]. No effect was seen on physical performance in a meta-analysis of eight placebo-controlled randomized trials (SMD = -0.01, 95% CI -0.29 to 0.27) [4]. A 2022 meta-analysis of 14 studies in athletes and active participants found no effect on most outcomes; the only significant effect observed was on vertical jump at high doses in the short term [5]. The effect size reported for that vertical-jump finding is implausibly large for its measure, so we do not rely on it [5].

Individual trials agree. In a placebo-controlled trial of 28 healthy young adults, 200 mg a day for 3 weeks did not change peak oxygen uptake, exercise time, workload or lactate [21]. In 31 healthy men who completed an 8-week trial of 200 or 400 mg a day of G115, ginseng did not change oxygen use, heart rate, lactate or perceived exertion compared with placebo [22]. A systematic review of 14 red ginseng trials found no improvement in aerobic capacity, although its authors noted the studies were few and the results mixed [23].

Does Panax ginseng affect mood or calmness?

The evidence is thin. In a crossover trial of 30 healthy young adults, 400 mg of G115 improved self-rated calmness, but only at 2.5 and 4 hours on the first day, and also improved mental arithmetic [17]. In the same trial, 200 mg slowed a fall in mood but slowed responses on the arithmetic task, and eight days of use added no benefit over a single dose [17]. A separate randomized, placebo-controlled trial gave 83 healthy young adults 200 or 400 mg of G115 or placebo for 8 weeks and found no effect on positive affect, negative affect or total mood disturbance [24].

What the evidence does not show

Long-term evidence is thin. A 2003 review of the human research found a lack of adequately controlled studies of repeated, long-term use [19], and the healthy-adult trials on this page lasted from a single dose to 8 weeks [16][17][22].

Research in older adults with mild cognitive impairment, Alzheimer's disease or dementia (a clinical population) is separate. A 2026 meta-analysis of 9 studies (617 patients) found slightly higher scores on a cognitive screening test (MMSE mean difference 0.38), but the improvement did not reach the threshold for clinical significance [25]. Results may not apply to healthy adults.

EMA describes ginseng root medicines as dried or steamed root, powders, liquid, soft or dry extracts, and herbal teas [10]. The acute cognitive trials tested people at set times after a single dose, from 1 hour up to 6 hours later [16][18]. A 2017 review reports that blood absorption of compound K, a ginsenoside metabolite, starts 4 hours after a dose of ginseng powder [11].

A systematic review of adverse effects concluded that the rate of adverse events with ginseng alone is similar to placebo, with headache, sleep problems and digestive upset the most common [6]. A systematic review of 65 randomized trials recorded 135 minor adverse events and no serious ones across the 40 trials that reported them [27]. A review of 44 trials (3,092 participants) found no significant difference from placebo in adverse events; its authors are affiliated with the research institute of the Korea Ginseng Corporation, a ginseng manufacturer [26].

NCCIH reports that short-term use by mouth, up to 6 months, in "recommended amounts" appears to be safe for most people, and that insomnia is the most common side effect [9]. It lists uncommon reports of severe rash, liver damage and severe allergic reactions, and notes that Asian ginseng may worsen autoimmune disorders and interfere with blood clotting [9]. The European Medicines Agency lists stomach discomfort, nausea, vomiting, diarrhea, constipation, skin reactions such as hives or itching, and insomnia, and says their frequency is not known [10].

Higher intakes bring more reports. A 2017 review notes insomnia and other nervous system effects in people taking more than 2.5 g a day, and a "ginseng abuse syndrome" of nervous system overactivity, skin eruptions and morning diarrhea has been described with high intakes of up to 15 g a day [11]. The same review reports vaginal bleeding and breast pain in some users, attributed to an estrogen-like effect [11]. Products that combine ginseng with other ingredients have been linked to serious adverse events and even fatalities, though other ingredients may have been responsible [6].

Ginseng may lower blood sugar. In healthy young adults, single doses of 200 or 400 mg lowered blood glucose levels [18], and NCCIH notes the same possibility [9]. In a crossover trial in young healthy volunteers, a drink with 800 mg of Panax ginseng did not significantly change ECG or blood pressure readings compared with placebo [28].

LiverTox, an NIH reference on liver injury, scores ginseng E: by itself, an unlikely cause of clinically apparent liver injury [36]. It notes that ginseng may cause herb-drug interactions that can lead to liver injury, and that commercial products vary widely in ginsenoside content, some containing none [36]. The entry covers Asian and American ginseng together.

A review of human interaction studies found they have been conflicting and have largely yielded negative results or only weak interactions [14]. In 12 healthy participants, 28 days of Panax ginseng (500 mg twice daily) reduced exposure to midazolam (geometric mean ratio for AUC 0.66), which suggests ginseng induced the liver enzyme CYP3A [7]; the review above describes this induction as weak [14]. Its authors advised close monitoring for people taking CYP3A-processed medicines with a narrow therapeutic range [7].

In an open-label randomized crossover study of 12 healthy men, 7 days of ginseng did not change warfarin levels or its effect on blood clotting (INR) [29]. In a randomized open-label study of 25 patients newly diagnosed with ischemic stroke (a clinical population), adding Panax ginseng did not change INR compared with warfarin alone [30]. A review of pharmacokinetic interactions concluded that interactions appear rare but still suggested close monitoring with warfarin and with narrow-range CYP3A or P-gp medicines [14]. American ginseng, a different species, did reduce warfarin's effect in a randomized trial of 20 healthy people [31]. A 2017 review advises that people on warfarin, other anticoagulants or antiplatelet drugs avoid ginseng supplements because of bleeding risk [11].

Other reports involve antidepressants. A systematic review records possible interactions with warfarin, phenelzine and alcohol [6], and psychiatric patients taking ginseng with phenelzine or other monoamine oxidase inhibitors have reported headaches, tremor and manic episodes [11]. A review also urges caution with digoxin and corticosteroids [11]. LiverTox describes liver injury that developed 1 to 3 months after people taking imatinib or raltegravir started ginseng; they had tolerated those medicines before and tolerated them again without ginseng [36]. The European Medicines Agency notes that no interactions had been described in the literature at the time of its assessment [10].

If you take any of these medicines, talk to your doctor or pharmacist before combining them with Panax ginseng.