Evidence explainerLion's mane mushroom
Does Lion's Mane Work? One Small Memory Trial, and Gains That Faded
Lion's mane is sold as a brain booster. The human evidence is a handful of small trials, with the best result fading within 4 weeks of stopping.
Key takeaways
- In 30 adults aged 50 to 80 with mild cognitive impairment, 3 g/day for 16 weeks raised cognitive scores versus placebo [1].
- Four weeks after stopping, those scores fell significantly [1].
- In 41 healthy young adults, a single 1.8 g amount sped up one task, but 28 days produced mostly null results [2].
- A 12-week trial reported better scores on one memory test (MMSE) but not on two others [3].
- Nerve-growth effects come from laboratory studies, not human trials [4].
Safety at a glance
From our Lion's mane mushroom monograph. Published interactions and cautions only, each with its source.
Who should be careful
- Mushroom allergy. Allergic reactions are listed among possible side effects of lion's mane.[4]
- Memory concerns. Trials were small and short; in one, gains faded within 4 weeks of stopping.[1]
- Before you start. Talk to your pharmacist or clinician before adding this supplement, especially if you take prescription medicines, are pregnant or breastfeeding, or have a chronic health condition.[4]
The evidence, graded
Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.
- Grade DImprovedCognitive function scores in older adultsCognitive scale scores rose significantly more than placebo at weeks 8, 12 and 16, then fell significantly 4 weeks after stopping. Laboratory tests showed no adverse effects.
- Grade DMixedCognition, stress and mood in healthy young adultsParticipants were quicker on the Stroop task 60 minutes after a single amount, and subjective stress trended lower after 28 days (p = 0.051). Null and some negative findings were also observed.
Older adults with memory problems
In a 16-week trial, 30 Japanese adults aged 50 to 80 with mild cognitive impairment took four 250 mg tablets of lion's mane powder three times a day, or placebo [1]. Cognitive scale scores rose significantly more than placebo at weeks 8, 12 and 16 [1].
Four weeks after stopping, the scores decreased significantly, and lab tests showed no adverse effects [1]. A separate 12-week trial found better MMSE scores but no change on two other memory tests [3].
Healthy young adults
In a pilot trial of 41 healthy adults aged 18 to 45, participants were quicker on the Stroop task 60 minutes after a single 1.8 g amount, and stress trended lower after 28 days (p = 0.051) [2]. Null and some negative findings were also observed, and the authors urge caution given the small sample [2].
In a crossover study, a single 1 g of a Nordic lion's mane extract improved a few reaction-time measures 1 to 2 hours later [5].
The nerve-growth idea
Compounds in lion's mane called hericenones and erinacines stimulate nerve growth factor synthesis in laboratory studies [6]. That has not been shown in people [4]. For safety, read lion's mane side effects.
Quick answers
Does lion's mane help brain fog?
No trial in our sources measured brain fog; the closest are small cognition trials with mixed results [1][2].
Does lion's mane give you energy or contain caffeine?
The trials in our sources used lion's mane powder or extract and did not measure energy [1][2]. A crossover study tested it alongside, but separately from, a guayusa tea extract [5].
How long does lion's mane take to work?
In the 16-week trial, scores were higher than placebo from week 8 [1].
Keep reading
Full monographs
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Browse the full Supplement & Nutrient Encyclopedia or all supplement articles.
References
- [1]Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment: a double-blind placebo-controlled clinical trial. Phytother Res, 2009.
- [2]The Acute and Chronic Effects of Lion's Mane Mushroom Supplementation on Cognitive Function, Stress and Mood in Young Adults: A Double-Blind, Parallel Groups, Pilot Study. Nutrients, 2023.
- [3]Improvement of cognitive functions by oral intake of Hericium erinaceus. Biomed Res, 2019.
- [4]Benefits, side effects, and uses of Hericium erinaceus as a supplement: a systematic review. Front Nutr, 2025.
- [5]Acute Effects of Naturally Occurring Guayusa Tea and Nordic Lion's Mane Extracts on Cognitive Performance. Nutrients, 2023.
- [6]Reduction of depression and anxiety by 4 weeks Hericium erinaceus intake. Biomed Res, 2010.