Do Mushroom Supplements Work? The Trials, Species by Species

Mushroom supplements have been tested in people far less than their reputation suggests, and the answer differs by species. Lion's mane has one 30-person placebo-controlled trial at 3 g a day in which cognitive scores rose over 16 weeks and fell back within four weeks of stopping; reishi did not change HbA1c, cholesterol or weight in a Cochrane review of 398 people with type 2 diabetes; cordyceps raised an exercise threshold by 10.5% in 20 older adults and changed nothing in 22 trained cyclists; chaga has never been tested in a human trial and carries a documented kidney hazard.^{1, 4, 7, 10, 11} No mushroom holds an authorised health claim in Great Britain, which is a statement about the register, not proof of no effect.

Do mushroom supplements work?

The trials are small, short and mostly unreplicated, and they differ by species, so the question cannot be answered as one thing. Where no trial exists the page says so: "not tested in people" is not "does nothing". The 2025 systematic review of lion's mane pooled the usable trials to a 1.17-point gain on a 30-point cognitive scale, in older adults with impairment; the Cochrane reviews of reishi found no effect on blood sugar or cholesterol and no survival data in cancer.^{4, 6, 15} Forum reports split between "life-changing" and "nothing", and both fit: an average effect at one dose in one population does not reach everyone.

What is a mushroom complex, and does a blend work better than one species?

A "mushroom complex" blends several species at a fraction of any trial dose. Six-mushroom blends are common. No trial has compared a blend with a single species, and two capsules cannot hold the 3 g a day of lion's mane from the one positive cognition trial and the 5.4 g a day of reishi extract from the fatigue trial at once.^{1, 5} That is not a verdict on the format; a blend delivers what its label states per serving.

Which mushroom is best for what? The species evidence table

Every row is a human trial or, for chaga, the absence of one; figures are from the published abstracts and nothing is read across between species.

So "which is better, lion's mane or reishi?" has a plain answer: they were tested for different things, never against each other. Brain: lion's mane is the only mushroom with placebo-controlled cognition trials, in older adults with impairment rather than healthy people with brain fog (what lion's mane is good for; does lion's mane help with ADHD). Energy: reishi's fatigue trial and cordyceps's threshold result (what reishi is good for; what cordyceps does for the body). Mood: one four-week trial of lion's mane cookies in 30 women with menopausal complaints, in which two mood-scale items differed from placebo; persistent low mood or anxiety is a GP matter.¹⁷ Sleep: no placebo-controlled trial of any mushroom. Gut, liver, hormones, PCOS, fertility, hair, inflammation, arthritis, longevity, "antioxidant" effects: nothing in the table measured them; testosterone belongs to shilajit's one trial. Zinc contributes to the maintenance of normal testosterone levels in the blood; that is authorised nutrient wording, not a mushroom finding (does zinc raise testosterone covers the trials). Kidneys: chaga is the one to avoid. Cholesterol: unchanged in reishi's trials.⁴ Healthiest: not a measured quantity (nor is "superfood"), and no trial has ranked species; as food, any cooked edible mushroom, and the shiitake and maitake studies used the whole mushroom (can you eat shiitake every day?; is maitake safe?).^{12, 13}

How long do mushroom supplements take to work, and when should you take them?

Judge by the trials, not the first week. In the lion's mane trial that found a difference, scores separated from placebo at week 8 and were still rising at 16; the reishi fatigue trial ran 8 weeks, the cordyceps trial 12, the maitake trial 18 and the one lion's mane study in early dementia 49.^{1, 5, 10, 13, 16} No trial measured blood levels, so there is no figure for how long a dose stays in your system; what there is, from the 16-week trial, is that the gain was gone four weeks after stopping.¹ No trial has compared morning with night: the 16-week trial split 3 g across three meals and the young-adult trial used one morning dose, so take it with a meal at a time you will remember.^{1, 2} No trial reported drowsiness, and reishi, sold for sleep, has no placebo-controlled sleep trial. How lion's mane makes you feel and how you feel after taking reishi gather the reports.

What do clinicians and regulators say about mushroom supplements?

The Great Britain nutrition and health claims register holds no authorised claim for any mushroom.²⁴ Every mushroom row on it (shiitake immune, reishi "stimulates the body in exhaustion", cordyceps antioxidant, immune and endurance, oyster mushroom, yeast beta-glucan) is non-authorised, and lion's mane, chaga and shilajit have no row at all. An absent claim is a statement about the register, which has not reassessed mushrooms since 2013, not proof that a mushroom does nothing. The Advertising Standards Authority said on 21 November 2024 that "there are no authorised claims for mushrooms themselves", that the word "functional" without an authorised partner claim "is likely to be a problem", and that medicinal claims belong only to MHRA-licensed medicines; it has upheld eight rulings since 2022 against focus, memory, immunity and "regrow brain cells" wording on mushroom gummies and drinks. So this site does not use "medicinal mushrooms" or "functional mushrooms" as a category, and the claims on a lawful UK mushroom gummy belong to its vitamins and minerals, not to the mushroom. Clinicians' advice is simpler: tell your GP or pharmacist what you take, because the interactions below are unstudied.

Is any mushroom supplement a novel food in the UK?

A novel food had no significant history of consumption in the UK or EU before 15 May 1997 and needs authorisation before sale.²⁵ The positions below come from European Commission consultations and the Finnish Food Authority, which GB tracks; the FSA's own species page could not be reached, so each is "GB position inferred".

• Lion's mane: fruiting body and its water extracts not novel (Commission consultation Ares(2025)1618080); dried mycelium powder novel (Ares(2019)6700914). So "is lion's mane illegal in the UK?" is no for the mushroom and its extracts, yes for mycelium products. The myth's root: wild hedgehog fungus, Hericium erinaceum, is protected under Schedule 8 of the Wildlife and Countryside Act 1981, so picking it is the offence.²⁶
• Reishi: fruiting body not novel; mycelium novel (the same 2019 document).
• Chaga: novel except broken, or as a water or ethanol extract, in a food supplement; in coffee, cocoa or smoothies it would need authorisation.
• Cordyceps: Ophiocordyceps sinensis and Samsoniella hepiali (the Cs-4 species) not novel; Cordyceps militaris treated by the FSA as a likely unauthorised novel food, recorded in an ASA ruling of 24 July 2024 (2025 Commission decisions: trade reports, unverified).
• Shiitake and maitake: long-standing foods; not novel.
• Shilajit: not novel only as a food supplement; in honey, coffee or drinks it is novel.

How do you read a mushroom supplement label?

Four things on a label tell you more than any claim. The part used: most human trials used the fruiting body, the mushroom itself, and the one lion's mane trial that used mycelium used one standardised to 5 mg/g of erinacine A, not mycelium-on-grain.¹⁶ Whether mycelium came with its grain, because grain starch inflates a "polysaccharide" figure unless beta-glucan is measured by the validated method that subtracts starch.²² The extract ratio against the milligrams: "10:1" means 10 g of mushroom made 1 g of extract, so "1,200 mg whole-mushroom equivalent" at 10:1 is about 120 mg of extract. And a beta-glucan percentage with a batch certificate of analysis, because in one survey only 5 of 19 reishi supplements matched their labels.²³ What mushroom powder is used for goes through powders, extracts, capsules, gummies and coffee by what each delivers per serving, ranking none above another.

What are the risks, and who should not take mushroom supplements?

Chaga and the kidneys. Chaga is extremely high in oxalate: one analysed powder held 14.2 g per 100 g, and three published cases of kidney failure followed months to years of daily powder at roughly 10 g a day or more, one in a person also taking 500 mg of vitamin C a day.^{7, 8, 9} People with kidney disease or a history of kidney stones should not take chaga without medical advice; can chaga be harmful has the full account, repeated on what chaga is good for, chaga tea every day and does chaga get you high.

Lion's mane and the forum reports. Anxiety, panic, low mood, depersonalisation, anhedonia, emotional blunting and low libido have been reported on online forums by people taking lion's mane, most with a disclosed confounder. The trials, to 10 g a day and 49 weeks, reported no serious adverse effects; the 2025 review lists stomach discomfort, headache and allergic reactions as under-reported possibilities; a PubMed search pairing lion's mane with those psychiatric terms returned no records on 8 October 2026.^{3, 15, 16} Lion's mane side effects has the full account; does lion's mane get you high answers the psychedelic confusion, and is shiitake a psychedelic does the same for shiitake.

Reishi powder and the liver. Reishi was well tolerated in trials at up to 4 g a day, but three published cases of liver injury, one fatal, involved reishi powder, one taken with alcohol.¹⁹ Dark urine, pale stools or yellowing on any supplement mean stop and see a GP.

Shiitake and the skin. Raw or undercooked shiitake can cause shiitake dermatitis, an itchy streaky rash a day or two after eating, lasting about ten days; a French poison-centre series recorded 59 cases in six years, and thorough cooking avoids it.¹⁸ A true mushroom allergy is a reason to take none of these.

Heavy metals. Raw shilajit and some Ayurvedic products have repeatedly tested positive for lead, arsenic and mercury, and lead poisoning from a contaminated cordyceps powder is on record; the trials used purified, batch-tested material.²¹

Medicines. Some trials of fungal beta-glucans changed immune markers in blood tests, which is a laboratory finding, not an authorised claim, so anyone on transplant medicines, biologics, chemotherapy or immunotherapy asks the specialist first; cordyceps is used in China as an add-on to transplant immunosuppressants.^{12, 20} Levodopa, MAO-B inhibitors, antidepressants, ADHD stimulants, anticoagulants and hormone therapies are unstudied with every species. The cross-species interaction table, marked known, theoretical or unstudied, is on the side effects of mushroom supplements. Nothing here is a reason to stop a prescribed medicine.

Everyone. No trial included pregnant or breastfeeding women or children, so none of these is recommended for them. No regulator has set an upper intake; "too many" means more than a trial used and, for chaga, any sustained daily powder. Suspected side effects from any supplement can be reported through the MHRA Yellow Card scheme.²⁷

Frequently asked questions

Is it good to take a mushroom complex every day?

The trials gave single species daily for 4 to 49 weeks without serious harm in the groups studied; a blend gives each at a fraction of those doses, and chaga in any daily blend carries the kidney caution above.

Do mushroom supplements make you sleepy?

No trial reported drowsiness for any species. Vivid dreams are reported on forums for lion's mane and have not been studied.

Does any mushroom increase testosterone?

No mushroom has been tested for testosterone in people; the one trial behind the question used shilajit, a mineral resin, at 500 mg a day for 90 days, and has not been repeated.¹⁴

Are mushroom supplements worth it?

That depends on whether a trial matches your situation, dose and form: a healthy adult taking 1.8 g of lion's mane for brain fog sits outside every positive trial; an older adult with memory concerns taking 3 g for 16 weeks sits inside one.^{1, 2}

Sources

1. Mori K, et al. Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment. Phytotherapy Research, 2009. PubMed 18844328.
2. Docherty S, et al. Acute and chronic effects of lion's mane supplementation on cognitive function, stress and mood in young adults. Nutrients, 2023. PubMed 38004235.
3. Grozier CD, et al. Four weeks of Hericium erinaceus supplementation does not impact markers of metabolic flexibility or cognition. International Journal of Exercise Science, 2022. PubMed 36582308.
4. Klupp NL, et al. Ganoderma lucidum mushroom for the treatment of cardiovascular risk factors. Cochrane Database of Systematic Reviews, 2015. PubMed 25686270.
5. Tang W, et al. A randomized, double-blind and placebo-controlled study of a Ganoderma lucidum polysaccharide extract in neurasthenia. Journal of Medicinal Food, 2005. PubMed 15857210.
6. Jin X, et al. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane Database of Systematic Reviews, 2016. PubMed 27045603.
7. Kikuchi Y, et al. Chaga mushroom-induced oxalate nephropathy. Clinical Nephrology, 2014. PubMed 23149251.
8. Lee S, et al. Development of end stage renal disease after long-term ingestion of chaga mushroom. Journal of Korean Medical Science, 2020. PubMed 32419395.
9. Kwon O, et al. Chaga mushroom-induced oxalate nephropathy that clinically manifested as nephrotic syndrome. Medicine, 2022. PubMed 35451393.
10. Chen S, et al. Effect of Cs-4 (Cordyceps sinensis) on exercise performance in healthy older subjects. Journal of Alternative and Complementary Medicine, 2010. PubMed 20804368.
11. Parcell AC, et al. Cordyceps sinensis (CordyMax Cs-4) supplementation does not improve endurance exercise performance. International Journal of Sport Nutrition and Exercise Metabolism, 2004. PubMed 15118196.
12. Dai X, et al. Consuming Lentinula edodes (shiitake) mushrooms daily improves human immunity. Journal of the American College of Nutrition, 2015. PubMed 25866155.
13. Jogi EM, et al. Maitake mushroom (Grifola frondosa) enhances cognitive function in healthy older Japanese. Journal of Nutritional Science and Vitaminology, 2026. PubMed 42055721.
14. Pandit S, et al. Clinical evaluation of purified shilajit on testosterone levels in healthy volunteers. Andrologia, 2016. PubMed 26395129.
15. Menon A, et al. Benefits, side effects, and uses of Hericium erinaceus as a supplement: a systematic review. Frontiers in Nutrition, 2025. PubMed 40959699.
16. Li IC, et al. Prevention of early Alzheimer's disease by erinacine A-enriched Hericium erinaceus mycelia. Frontiers in Aging Neuroscience, 2020. PubMed 32581767.
17. Nagano M, et al. Reduction of depression and anxiety by 4 weeks Hericium erinaceus intake. Biomedical Research, 2010. PubMed 20834180.
18. Boels D, et al. Shiitake dermatitis: French Poison Control Centre experience, 2014 to 2019. Clinical Toxicology, 2022. PubMed 35404185.
19. Wanmuang H, et al. Fatal fulminant hepatitis associated with Ganoderma lucidum (lingzhi) mushroom powder. Journal of the Medical Association of Thailand, 2007. PubMed 17621752.
20. Hong T, et al. Cordyceps sinensis (a traditional Chinese medicine) for kidney transplant recipients. Cochrane Database of Systematic Reviews, 2015. PubMed 26457607.
21. Saper RB, et al. Lead, mercury and arsenic in Ayurvedic medicines sold via the Internet. JAMA, 2008. PubMed 18728265.
22. McCleary BV, Draga A. Measurement of beta-glucan in mushrooms and mycelial products. Journal of AOAC International, 2016. PubMed 26957216.
23. Wu DT, et al. Quality consistency of Ganoderma lucidum dietary supplements collected in the United States. Scientific Reports, 2017. PubMed 28798349.
24. Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. gov.uk.
25. Food Standards Agency. Novel foods: regulated products guidance. food.gov.uk.
26. Wildlife and Countryside Act 1981, Schedule 8: protected plants, including the hedgehog fungus Hericium erinaceum. legislation.gov.uk.
27. MHRA. Yellow Card: report a suspected side effect. yellowcard.mhra.gov.uk.

This article is general information, not medical advice. No mushroom or shilajit supplement has an authorised health claim in Great Britain, none has been tested in pregnancy, breastfeeding or childhood, and anyone taking a regular medicine, or with kidney disease, liver disease or a mushroom allergy, should ask a pharmacist or GP before starting one.