Panax ginseng

What it is

Panax ginseng is a root used in East Asian herbal medicine. Trials use Asian ginseng, American ginseng, Korean red ginseng and enzyme-modified extracts [1][2][3].

How it might work

Proposed mechanism: ginseng may lower blood glucose, and the short trials in healthy adults suggest mental effects may be linked to this [4][5]. Antioxidant effects have also been proposed for fatigue [6]. These are proposals from the trial authors, not established mechanisms.

What the research says

Tiredness: a 2023 review of 19 trials found no significant overall reduction in fatigue, though herbal formulas and general fatigue improved [7]. A 2016 review of four trials found an effect of 0.34 [8], and a 2022 review of 12 trials found 0.33 [9]. Both are modest effects.

Memory and attention: a 2024 review of 15 trials (671 people) found a small memory gain, with an effect of 0.19, and no clear effect on attention or executive function [10]. Single-dose trials in healthy young adults have been mixed [4][11].

Doses used in studies

Single doses of 200 mg and 400 mg of an extract (G115) were tested in healthy adults [4]; a single 1,200 mg dose was tested in a driving study [11]. Daily doses ranged from 100 mg to 2 g in fatigue and cognition trials [12][6]. A 2016 trial used 2 g a day of an enzyme-modified extract for four weeks [3].

Safety and interactions

Common side effects were headache, sleep problems and stomach upset, at about the same rate as placebo [13][7]. Combination products containing ginseng have been linked to serious side effects and deaths, although other ingredients may be responsible [13]. Ginseng lowered blood glucose within an hour in healthy adults [5], so people with diabetes or on blood sugar medicines should ask a doctor first. A single dose slightly increased warfarin clearance in healthy people [14], but small studies in people taking warfarin found no significant change in INR [15][16]. No upper intake limit was reported in the studies read [13]. Pregnancy, breastfeeding and children were not covered in the studies read [13].

Caveats and open questions

Most trials are small and short, and products and doses differ widely [7][3]. The 2023 review found no significant overall fatigue effect, while earlier reviews found modest benefit [8][9]. The memory result comes from one review that includes people with cognitive impairment and Alzheimer's disease [10]. Larger trials of standardised products in healthy adults are needed [1].