Users Report Anxiety, Panic and Long-lasting Symptoms After Taking Lion’s Mane Supplements

A rising number of consumers say they experienced new or worsened psychiatric and neurological symptoms after taking lion’s mane mushroom supplements, reporting an initial boost in focus followed by headaches, panic attacks, dissociation and prolonged cognitive difficulties.

Two detailed accounts shared with media outlets describe otherwise healthy adults who began taking over‑the‑counter lion’s mane capsules to aid concentration and digestion and later developed severe symptoms. One woman in Glasgow, identified as Robyn Ramsay, said she started the supplement while finishing a postgraduate counselling diploma and noticed improved focus but developed headaches within three weeks and a first panic attack about two weeks later. She continued the supplement for several more weeks, then stopped after seeing an online report linking similar symptoms to lion’s mane; her anxiety eased over months, and she said she was about 95% back to normal a year later.

A second case, a man who gave only a pseudonym, said he took a single 700 mg capsule daily in mid‑2023 and initially felt more creative and mentally fluent. Within weeks he developed headaches, dizziness and a flu‑like malaise; after about a month his condition deteriorated into depression, episodes of disorientation and severe fatigue that persisted despite stopping the supplement and receiving psychiatric care. He said he still experiences problems reading and following television and that recovery has been slow.

The anecdotal reports appear to be part of a larger online community: posts on the Reddit platform describe similar experiences, and moderators report about 25,000 members in a forum where users share suspected adverse reactions. Sales of lion’s mane supplements have risen sharply in the United Kingdom in the past year, with Nielsen data showing a 1,300% increase, an uptick industry officials say reflects growing consumer interest.

Researchers and clinicians say the biological activity of lion’s mane (Hericium erinaceus) provides a plausible explanation both for reported benefits and potential adverse effects, but they also emphasise that clinical evidence remains limited. Laboratory studies and small clinical trials point to compounds in the mushroom — notably hericenones and erinacines — that may stimulate production of nerve growth factor, support neuron health and reduce inflammation and oxidative stress. A 2009 randomized trial published in Phytotherapy Research found cognitive improvements in 30 older adults with mild cognitive impairment after 16 weeks of lion’s mane. A 2019 placebo‑controlled trial in Biomedical Research International reported improved performance on a cognitive test in 31 healthy adults over 50 after 12 weeks of 3.2 grams daily.

Catalina Fernandez de Ana Portela, a biologist who has conducted research and clinical trials on mushrooms, said lion’s mane’s mechanisms include protecting neurons and acting as a prebiotic that may improve gut microbial diversity. She has advocated for use among older adults in some contexts but said side effects are uncommon in her experience. Other experts urge caution. Edzard Ernst, former professor of complementary medicine at the University of Exeter, said preliminary evidence suggests potential benefits but warned that therapeutic claims remain under‑researched and that reported risks range from allergic and digestive reactions to sleep disturbances and psychiatric symptoms including panic attacks.

Nicholas Money, a biology professor who has studied mushrooms, pointed to parallels with research on psychedelic‑assisted therapies: while some individuals benefit, a minority can experience catastrophic adverse psychological reactions. "If lion’s mane actually affects the nervous system," he said, "then it could provoke anxiety too." Money and others note that mushrooms can bioaccumulate environmental contaminants such as heavy metals, a factor that may complicate assessments of safety depending on cultivation and sourcing.

Manufacturers and trade groups say the industry follows food‑safety regulations. Martin Last, director general of the Health Foods Manufacturers’ Association, said the HFMA promotes high production standards and compliance with Food Standards Agency guidance to ensure product safety and quality. Catalina Fernandez de Ana Portela, who runs a company that produces lion’s mane supplements, argued that adverse reactions may relate to contaminants in the growing medium rather than the mushroom itself, since fungi concentrate compounds from their substrate.

Regulatory experts note a key difference between supplements and medicines: in many jurisdictions, dietary supplements are regulated as foods rather than drugs, meaning they are subject to less rigorous pre‑market testing for safety and efficacy. That regulatory gap makes it difficult to quantify the frequency and severity of adverse events and to determine causation for individual cases. Health care professionals say that while controlled clinical trials have suggested possible cognitive and gut‑health benefits, those trials involved small sample sizes and short durations.

Clinicians contacted for comment recommended that people experiencing new or worsening psychiatric or neurological symptoms seek medical evaluation and discuss any supplements they are taking with a health care provider. They also advised caution for people with pre‑existing psychiatric conditions, autoimmune disorders such as multiple sclerosis, lupus or rheumatoid arthritis, or those taking medications like blood thinners that could interact with herbal products.

Researchers called for larger, well‑designed clinical trials to clarify both potential benefits and risks, and for improved adverse‑event reporting systems to capture supplement‑related harms. Consumers and patient advocates urged clearer labelling, independent product testing and tighter oversight of claims made by manufacturers.

Until more conclusive evidence is available, experts say, health care providers and consumers should treat lion’s mane as a biologically active substance with unknown risk profiles for some individuals. The accounts of prolonged and debilitating symptoms highlight the challenge of balancing enthusiasm for promising natural products with the need for systematic evaluation of safety and efficacy.