Lion's Mane Mushroom: What the Human Evidence Shows

What Is Lion's Mane?

Lion's Mane (Hericium erinaceus) is an edible and medicinal mushroom native to North America, Europe, and Asia. Named for its distinctive cascading white spines resembling a lion's mane, it is eaten as a food and has a history of use in traditional East Asian medicine. Traditional use is not evidence of benefit or safety.

What distinguishes Lion's Mane from many other cognitive supplements is its proposed mechanism. In laboratory and animal studies, Lion's Mane extracts and compounds stimulate the production of Nerve Growth Factor (NGF), a protein that supports the growth and maintenance of neurons.^3,4 Whether this happens in people who take Lion's Mane supplements, and whether it affects thinking or memory, has not been established.

Judged by clinical evidence rather than mechanism alone, the human data are limited to a few small trials, with important caveats about what the evidence does and does not support.

The Mechanism: How Lion's Mane Affects the Brain

Nerve Growth Factor Stimulation

The main compounds studied in Lion's Mane are hericenones (found in the fruiting body) and erinacines (found in the mycelium). In cell studies, both classes of compounds can induce NGF synthesis in nerve cells.³ In rats, erinacine A was detected in the brain after oral dosing,¹¹ but we did not find equivalent data for hericenones, and effects on NGF in the human brain have not been shown.

NGF is not a minor player in brain health. It is essential for:

• The survival and maintenance of neurons in the hippocampus (memory center) and basal forebrain
• Neuroplasticity — the brain's ability to form new connections and reorganize in response to learning and experience
• The repair of damaged neural pathways following injury or disease
• The function of cholinergic neurons, which are selectively lost in Alzheimer's disease

NGF has been studied for its role in the brain, but whether it explains any effect of Lion's Mane in people has not been established. The NGF findings come mainly from cell and animal studies,^3,4 and the human trials described below did not show that NGF was the cause of any change in test scores.

BDNF

Some research also reports that Lion's Mane preparations raise Brain-Derived Neurotrophic Factor (BDNF), another protein involved in nerve cell growth and learning. A 2025 systematic review describes increased pro-BDNF and BDNF production across the studies it included,⁷ but much of this is laboratory and animal work. In one human study of people with overweight or obesity, circulating pro-BDNF rose after 8 weeks of Lion's Mane while BDNF did not change significantly.¹⁴ It is not known whether these changes matter for brain health.

What the Clinical Evidence Shows

The Mori et al. Trial (2009)

One of the few clinical trials of Lion's Mane was conducted by Mori and colleagues and published in Phytotherapy Research.¹ In this double-blind, placebo-controlled study, 30 Japanese adults aged 50 to 80 with mild cognitive impairment were randomized (15 per group) to take tablets containing Lion's Mane dry powder (3 g/day in total) or placebo for 16 weeks. The first author's listed affiliation is the mushroom laboratory of a company (Hokuto Corporation).

On a cognitive function scale based on the Revised Hasegawa Dementia Scale (HDS-R), the Lion's Mane group scored significantly higher than the placebo group at weeks 8, 12 and 16, and scores rose with the duration of intake. Four weeks after intake stopped, the scores had decreased significantly.¹ Two cautions apply:

1. This is a single small trial of 30 people, so the result needs confirmation in larger studies
2. Because scores fell after intake stopped, any effect seen did not appear to last without continued use

Mood and Self-Reported Symptoms

A separate 4-week study by Nagano and colleagues (2010) gave Lion's Mane cookies or placebo cookies to 30 women and assessed menopausal symptoms, depression, sleep quality and a list of general complaints.² Depression and general-complaint scores were lower after Lion's Mane intake than before it. Compared with placebo, however, only two items on the general-complaints scale were significantly lower, and anxiety only tended to be lower. The authors described the finding as a possibility and noted that it suggests a mechanism different from NGF enhancement.² Another study, in 77 people with overweight or obesity following a low-calorie diet, reported lower depression, anxiety and sleep-disorder scores after 8 weeks of Lion's Mane.¹⁴

Nerve Regeneration Research

In a rat study of crush injury to a peripheral nerve, daily oral Lion's Mane extract was associated with earlier return of limb function than in untreated rats.¹² We did not find human trials of Lion's Mane for nerve injury, so this remains an animal finding.

Fruiting Body vs Mycelium

Lion's Mane products differ in the part of the mushroom they are made from, and clinical trials have tested different preparations:

• Fruiting body products contain hericenones and polysaccharides. One trial tested a 10:1 fruiting body extract as a single 3 g dose.¹⁰
• Mycelium products contain erinacines. One 49-week trial used capsules of erinacine A-enriched mycelia.⁶ What else is in a mycelium product depends on how it was grown, so check whether the label states the growing substrate.
• Full-spectrum extracts combining both fruiting body and mycelium may contain both compound classes, but amounts differ between products and no trial has tested them against single-source products.

When choosing a Lion's Mane supplement, look for a label that states whether the product is made from the fruiting body, the mycelium or both, and how much mushroom each serving contains. Trial results apply only to the specific preparations that were tested.

Dosage: What Trials Have Used

No dose-finding studies of Lion's Mane were found, so there is no evidence-based dose. Human trials have used different preparations and amounts that cannot be compared directly: 3 g/day of dry mushroom powder for 16 weeks,¹ three 350 mg capsules a day (about 1 g/day) of erinacine A-enriched mycelia for 49 weeks,⁶ 1.8 g/day for 28 days in healthy young adults,⁸ and a single 3 g dose of a 10:1 fruiting body extract.¹⁰ Extract products vary widely in strength, so a milligram figure on an extract label cannot be matched to these trial amounts. Follow the product label and do not exceed it.

In practice:

• Before use: Ask a doctor or pharmacist before use if you take medicines or have a health condition. Do not use Lion's Mane as a substitute for assessment of memory problems
• Duration: Trials ran from a single dose to about a year (49 weeks), and most lasted 4 to 16 weeks. Safety beyond about a year has not been studied, so discuss ongoing use with your doctor

Safety and Contraindications

In the small clinical trials done so far, Lion's Mane has generally been well tolerated. A 16-week trial using 3 g/day of dry mushroom powder found no adverse effects on laboratory tests,¹ and a 49-week trial of a mycelium product reported only four dropouts, for abdominal discomfort, nausea and skin rash.⁶ A 2025 systematic review lists stomach discomfort, headache and allergic reactions as possible side effects and notes that side effects are commonly unreported.⁷ A case report described raised liver enzymes in a patient taking a mushroom powder supplement that contained both Agaricus blazei and Lion's Mane; the authors linked the effect mainly to Agaricus.¹⁵ Trials have been small and relatively short, so long-term safety is not well established.

Cautions:

• Mushroom allergy: Anyone with a known mushroom allergy should avoid Lion's Mane. Skin rash and allergic reactions have been reported,^6,7 and allergic contact dermatitis from handling the mushroom has been described.¹³ Stop use and seek medical help if you develop hives, swelling or difficulty breathing
• Autoimmune conditions and immunosuppressants: Lion's Mane contains bioactive polysaccharides that have shown anti-inflammatory effects in laboratory studies.⁷ Its effects in people with autoimmune disease or taking immunosuppressants have not been studied, so check with your doctor first
• Pregnancy and breastfeeding: We did not find safety data, so avoid use during pregnancy and nursing
• Blood thinners and surgery: A compound from Lion's Mane (hericenone B) reduced platelet aggregation in laboratory experiments with rabbit and human platelets.⁹ No human bleeding data were found, but anyone taking warfarin or antiplatelet medicines, or facing surgery, should check with their doctor or pharmacist first
• Diabetes and other medicines: We did not find studies of Lion's Mane in people taking diabetes medicines or other prescription medicines. Ask your prescriber or pharmacist before use

Editorial Assessment

The evidence for Lion's Mane in people is limited. The NGF findings come from cell and animal studies. The main human result is one 16-week trial of 30 older adults with mild cognitive impairment,¹ alongside a 49-week pilot trial of a mycelium product in people with mild Alzheimer's disease, which reported higher cognitive scores in the treated group.⁶ Trials in healthy younger adults found limited or no overall benefit.^8,10 Results from different preparations cannot be combined, and larger, longer trials are needed.

Lion's Mane is not a treatment for Alzheimer's disease, dementia or other neurodegenerative conditions, and the current evidence does not show that it prevents them. Anyone with memory concerns should talk to a doctor.

Lion's Mane is often discussed for brain fog and mild memory lapses, but human evidence for these concerns is limited. It has been reasonably well tolerated in small, short trials, while long-term safety and interactions with medicines are not well studied.⁷