Brain & Focus
Lion's Mane: How Long It Takes, and What Happened After
Key takeaways
- Mori 2009: 30 people, 3 g daily, significant gains at weeks 8, 12 and 16.
- Four weeks after stopping, the scores decreased significantly. The effect did not persist.
- That trial was in adults aged 50 to 80 with mild cognitive impairment, not in healthy people.
- In 43 healthy adults aged 18 to 45, Stroop speed improved but word recall accuracy got worse.
- A single 3 g dose in 18 healthy adults produced no significant effect on global cognitive function.
- LiverTox likelihood score E: unlikely cause of clinically apparent liver injury, no case reports.
Almost every page about lion’s mane cites the same trial. Almost none of them quotes the last line of its results.
The trial
Mori and colleagues, 2009. Thirty Japanese adults aged 50 to 80 with mild cognitive impairment, randomised into two groups of fifteen.
The dose: four 250 mg tablets of 96% Yamabushitake dry powder, three times a day. 3 g daily, for 16 weeks.
The outcome: a cognitive function scale based on the Revised Hasegawa Dementia Scale.
The result:
At weeks 8, 12 and 16 of the trial, the Yamabushitake group showed significantly increased scores on the cognitive function scale compared with the placebo group.
That is a real finding and it is the reason this mushroom has the reputation it has.
The sentence that follows it
At week 4 after the termination of the 16 weeks intake, the scores decreased significantly.
They stopped taking it. Within a month, the gains were gone.
One small trial cannot settle this, and no other study has tested the same question. But it is the only direct evidence there is, and it changes what the product is. On this data lion’s mane is not a course that leaves you better off. It is something you take continuously while it does whatever it does.
That is worth knowing before you start, because it changes the cost calculation from one purchase to an indefinite one.
Two things about who was in that trial
They were 50 to 80. Not students, not knowledge workers looking for an edge.
They had mild cognitive impairment. A diagnosis, not a bad week.
Neither of those describes most people buying this. Extending a result from a clinical population to a healthy one is the single most common move in supplement marketing, and it is not supported by anything here.
What happened when they did test healthy people
43 volunteers, aged 18 to 45, mean age 26, 1.8 g daily for 28 days:
| Finding | Result |
|---|---|
| Stroop task speed, acute | Faster (p=0.005) |
| Immediate word recall accuracy | Worse (p=0.013) |
| Delayed word recall over 28 days | Placebo improved more |
| Subjective stress at 28 days | Trend only (p=0.051), on one scale of two |
Read the second row again. On one measure the supplement group did worse than placebo. That is not a result anyone would put on a bottle, and it is exactly why single-outcome reporting is misleading in this literature.
The authors are straightforward about why not to over-read any of it: the small sample size meant the study was likely underpowered to detect the probable, modest cognition-enhancing effects.
18 healthy adults, single 3 g dose of a 10:1 extract, crossover design:
No significant effect of the H. erinaceus fruiting body extract for composite measures of global cognitive function.
Pegboard performance improved at 90 minutes. Flanker and Trail Making B got worse. The conclusion: acute consumption did not demonstrate a significant overall improvement, and any benefits may be task or domain specific.
The safety file is genuinely clean
This is where lion’s mane does better than most of the shelf it sits on.
LiverTox, the NIH’s drug-induced liver injury database, assigns it a likelihood score of E: unlikely cause of clinically apparent liver injury. E is the best score in that system.
There have been no case reports of clinically apparent liver injury attributed to lion’s mane.
And it has not been linked to serum enzyme elevations during therapy. Its summary word is that lion’s mane is generally recognised as safe.
The Mori trial adds that laboratory tests showed no adverse effect over 16 weeks at 3 g daily.
So the honest position is: weak efficacy evidence, clean safety evidence. Those are different axes, and lion’s mane scores very differently on each. A lot of supplements manage the reverse.
Fruiting body versus mycelium, which is not a detail
The trials used the fruiting body, the actual mushroom.
A large share of what is sold is mycelium grown on grain, harvested and milled with the grain still in it. That means a meaningful proportion of the powder is starch from the growing substrate rather than mushroom.
If the label does not say fruiting body, you cannot match any published dose with it, because you do not know how much mushroom is in there. For an extract, you also need the ratio: 3 g of a 10:1 extract and 3 g of dried powder are not the same thing by an order of magnitude.
If you test it, test it properly
- Fruiting body, stated on the label.
- Around 3 g a day, divided across the day, matching the trial rather than a marketing dose.
- At least eight weeks, because week 8 is the earliest point anyone measured a difference.
- Decide in advance what you are measuring. Otherwise the only thing you will assess at week eight is how you feel about having spent the money, which is not the same variable.
And go in knowing the finding at the end of the one trial that followed people after they stopped.
Frequently asked questions
How long does lion's mane take to work?
On the only trial that showed a clear cognitive benefit, the first significant timepoint was week 8. Mori and colleagues measured at weeks 8, 12 and 16 and found significantly increased scores on a cognitive function scale based on the Revised Hasegawa Dementia Scale at all three, compared with placebo. There is no published evidence for a meaningful benefit at two weeks, which is where most people give up or decide it works. If you are going to try it, the honest minimum trial period is eight weeks at a trial-comparable dose.
What happens when you stop taking it?
In the one trial with follow-up, the gains went away. The exact finding: at week 4 after the termination of the 16 weeks intake, the scores decreased significantly. That is a single small study and it should not be over-read, but it is the only direct evidence on the question and it points one way. It also reframes what the supplement is: on this evidence it behaves like something you take continuously for an ongoing effect, not a course of treatment that leaves you improved.
Does it work in healthy people?
The evidence there is thinner and less flattering. In 43 volunteers aged 18 to 45 taking 1.8 g daily for 28 days, the supplement group performed faster on the Stroop task acutely (p=0.005) but showed worse accuracy on immediate word recall (p=0.013), and on delayed word recall the placebo group improved more. A separate crossover study of 18 healthy adults aged 18 to 35 given a single 3 g dose of a 10:1 extract found no significant effect for composite measures of global cognitive function, with improvement on a pegboard test at 90 minutes and worse performance on Flanker and Trail Making B. The authors of that study concluded that acute consumption did not demonstrate a significant overall improvement and any benefits may be task or domain specific.
Is lion's mane safe?
This is the strongest part of the file. LiverTox, the NIH database of drug-induced liver injury, assigns lion's mane a likelihood score of E, meaning unlikely cause of clinically apparent liver injury, and states that there have been no case reports of clinically apparent liver injury attributed to lion's mane and that it has not been linked to serum enzyme elevations during therapy. Its summary is that lion's mane is generally recognised as safe. The Mori trial also reported that laboratory tests showed no adverse effect. An E score is the best rating in that system, and it is worth knowing that plenty of popular supplements do not have one.
How much should I take?
If you are matching the trial, 3 g per day of dried fruiting body powder, taken as divided doses across the day rather than all at once, which is how Mori's participants took it: four 250 mg tablets three times daily. The 43-person study used 1.8 g daily and found little. Note what is being measured in grams here: dried mushroom powder, not extract. A 10:1 extract at 3 g is a very different quantity of raw material, and the two are not interchangeable on the label.
Fruiting body or mycelium?
The trials that reported benefit used the fruiting body, the actual mushroom. Much of the cheaper supply is mycelium grown on grain and sold with the grain still in it, which means a meaningful share of what you are buying is starch rather than mushroom. This is not a subtle marketing distinction; it changes what is in the capsule. If a label does not say fruiting body, or does not disclose the ratio for an extract, you cannot match any published dose with it.
Why is the evidence so thin for something this popular?
Because the studies are small. Thirty people, 43 people, 18 people. The 43-person study's own authors state it was likely underpowered to detect the probable, modest cognition-enhancing effects, which is a fair description of the whole literature. Nothing here rules out a real effect; what it rules out is confidence. Popularity and evidence are separate things, and lion's mane is a case where the gap between them is unusually wide.
Is it worth trying?
It is a defensible thing to try and a poor thing to rely on, and the safety profile is the reason for the first half of that sentence. If you do try it, do it properly: a fruiting body product at around 3 g daily, for at least eight weeks, with some way of noticing whether anything changed that is not just how you feel about having spent the money. And know going in that the one trial with follow-up found the benefit faded within four weeks of stopping.
Sources
Every claim above is drawn from these primary sources. Last checked July 2026.
- 1.Mori K et al. Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment: a double-blind placebo-controlled clinical trial. PMID 18844328. Thirty subjects aged 50 to 80 with mild cognitive impairment randomised into two 15-person groups; four 250 mg tablets containing 96% Yamabushitake dry powder three times a day for 16 weeks; cognitive function assessed with a scale based on the Revised Hasegawa Dementia Scale. At weeks 8, 12 and 16 the Yamabushitake group showed significantly increased scores compared with placebo. At week 4 after the termination of the 16 weeks intake, the scores decreased significantly. Laboratory tests showed no adverse effect. Checked 10 August 2026
- 2.LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, Lion's Mane. Likelihood score E, unlikely cause of clinically apparent liver injury. There have been no case reports of clinically apparent liver injury attributed to lion's mane, and it is not mentioned or listed in large case series or systematic reviews. Lion's mane has not been linked to serum enzyme elevations during therapy or clinically apparent liver injury, and is generally recognised as safe. Checked 10 August 2026
- 3.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. PMID 38004235. 43 volunteers aged 18 to 45, mean age 26.35 years, randomised double-blind placebo-controlled parallel-groups design, 1.8 g Hericium erinaceus daily for 28 days. Acutely at 60 minutes the supplement group performed faster on the Stroop task (p=0.005) but showed worse accuracy on immediate word recall (p=0.013). After 28 days a trend towards reduced subjective stress was observed (p=0.051) on Visual Analogue Scales but not on the Perceived Stress Scale, and placebo recipients showed greater improvement in delayed word recall. Authors state the small sample size meant the study was likely underpowered to detect the probable, modest cognition-enhancing effects. Checked 10 August 2026
- 4.Acute effects of a standardised extract of Hericium erinaceus on cognition and mood in healthy younger adults: a double-blind randomised placebo-controlled study. PMID 40276537. Eighteen healthy participants aged 18 to 35, double-blinded placebo-controlled acute crossover design, single dose of 3 g of a 10:1 extract. No significant effect of the H. erinaceus fruiting body extract for composite measures of global cognitive function; improved performance on the pegboard test at 90 minutes; no significant improvements in mood; performance worsened on Flanker and Trail Making B. Authors' conclusion: acute consumption did not demonstrate a significant overall improvement in cognitive performance and mood compared to placebo, and any benefits may be task or domain specific. Checked 10 August 2026