What is lion's mane? A plain-English guide

Lion's mane is a mushroom that grows on dead hardwood trees [1]. It has long, white spines that hang down like a lion's mane [1]. Other names include bearded tooth, monkey head and pom pom mushroom [1].

It is used in East Asian cooking, eaten raw, dried or cooked [1]. It is also sold as a dietary supplement in capsules, powders and liquid extracts [1]. It has a long history of use in Native American and East Asian medical systems [1].

How it might work (lab and animal research)

In lab and animal studies, two groups of natural chemicals in lion's mane passed from the blood into the brain [1]. A 2025 review looked at cell and rodent studies of chemicals from the fungus's root-like threads [5]. In animals, these chemicals increased neurogenesis (the growth of new nerve cells) [5].

This is lab and animal work, not an effect measured in people, so we do not grade it. As of November 11, 2026, the sources we checked (PubMed and Europe PMC) show no human trial of nerve cell growth after lion's mane.

A systematic review is a study that gathers the research on one question. A 2025 review of lion's mane found 5 trials that split people into groups by chance, plus 3 pilot trials [6]. Some tested memory and thinking [6]. Separate trials tested mental speed and mood in healthy young adults, including one with company-linked authors [3][4].

The 2025 review could not combine the trials into one answer [6]. The studies it included reported their results in incomplete or unclear ways [6].

The four trials below compared lion's mane with a placebo, a dummy pill with nothing active in it [2][3][4][8]. Chance decided who got which, or in what order [2][3][4][8]. Neither the people nor the researchers knew who took what [2][3][4][8].

Does lion's mane help memory and thinking?

Evidence grade for global cognition: C, limited. Why this grade

One trial in Japan was led by a researcher from a mushroom company [2]. In that company-led trial, 30 adults aged 50 to 80 with mild cognitive impairment took lion's mane tablets or a placebo for 16 weeks [2]. Mild cognitive impairment means memory and thinking problems that a doctor can measure but that are not severe.

The lion's mane group beat placebo on a thinking test at weeks 8, 12 and 16 [2]. But 4 weeks after people stopped, scores fell again [2]. A 2024 review called this trial very small and said its temporary benefit has not yet been repeated [7]. Results in people with mild cognitive impairment may not apply to healthy adults.

In a second trial in Japan, 31 healthy adults averaging about age 61 took lion's mane powder or a placebo for 12 weeks [8][6]. The lion's mane group improved on one of three memory and thinking tests, but not on the other two [8].

Does lion's mane speed up thinking?

Evidence grade for reaction time: C, limited. Why this grade

Evidence is mixed in small trials in healthy young adults [3][4].

One trial tested 1.8 g of lion's mane against a placebo in healthy adults aged 18 to 45 [3]. It looked at one dose in 43 people and at 28 days of use in 41 people [3]. The maker supplied the capsules [3]. At 60 minutes after one dose, the lion's mane group was quicker on a test that uses color words [3]. Other results showed no effect, and a few were negative [3]. The authors urged caution because the trial was small [3].

Another trial had two authors who worked for a drinks company that uses lion's mane [4]. The same company paid part of the fee to publish the paper [4]. In it, 18 healthy adults aged 18 to 35 took one 3 g extract dose and, at another visit, a placebo [4]. Overall thinking and mood scores showed no clear difference from placebo [4].

Results changed between tests and between trials [3][4]. So a steady effect on mental speed has not been shown.

To see what each grade means, read how we grade evidence.

Table: Doses used in studies (not a recommendation)

These are research amounts, not advice. Talk to a clinician before trying any supplement.

Memorial Sloan Kettering (MSKCC), a US hospital, says lion's mane is generally safe in food and tea [1]. It advises people to talk with their healthcare providers before taking lion's mane supplements [1].

MSKCC lists belly discomfort, nausea and skin rash as possible side effects [1]. The 2025 review lists stomach discomfort, headache and allergic reactions as possible side effects that often go unreported [6]. In the company-led 16-week trial, 7 people on lion's mane and 6 on placebo reported mild stomach discomfort and diarrhea, the review says [6].

A case report (a write-up of one patient) described a 63-year-old man in intensive care [9]. He had severe breathing failure after taking a lion's mane extract [9]. A lab test showed his white blood cells reacted strongly to the extract, and he recovered with steroid treatment [9]. A 2024 review notes one case of anaphylaxis, a severe allergic reaction, after a person ate fresh lion's mane [7]. Single case reports cannot show how often such reactions happen.

As of November 11, 2026, the sources we checked (PubMed and MSKCC) show no study of drug interactions with lion's mane. They name no medicine that interacts with it. If you take any medicines, talk to your doctor or pharmacist before combining them with lion's mane.

• People who are pregnant or breastfeeding: the label of a lion's mane product licensed in Canada says to consult a health care practitioner before use [10].
• People who take medicines: MSKCC notes that herbal supplements can interact with some medicines and change how they work [1].
• People who have reacted to lion's mane before: the case reports above describe severe breathing failure and anaphylaxis [7][9].