Reishi Mushroom: Benefits, Side Effects, Dosage and Best Time to Take It

What is reishi?

Reishi, called lingzhi in Chinese, is a shiny, reddish-brown shelf fungus that grows on hardwood trees. It’s too tough and bitter to eat, so it’s taken as a tea, powder or extract. It has been used in Chinese and Japanese tradition for centuries, and today most people in the UK take it as an evening drink. It isn’t psychoactive and contains no psilocybin.

What is in reishi: triterpenes and beta-glucans

Two groups of compounds get most of the research attention:

• Beta-glucans: long chains of sugars (polysaccharides) found in the walls of mushroom cells. They are the compounds most studied for effects on immune cells, mainly in the lab.
• Triterpenes: reishi produces large amounts of these bitter-tasting compounds, including the ganoderic and ganoderenic acids. Most of the research on them is in the lab or in animals.

Memorial Sloan Kettering Cancer Center and the US National Cancer Institute both name beta-glucans and triterpenes as reishi’s main active compounds, with lipids and proteins less studied. How much of each a product contains depends on the species, the part used and how it’s extracted, which is why two reishi products can be very different.

Red reishi, fruiting body and mycelium

“Red reishi” is the name most labels use for the common shiny, reddish-brown reishi, sold as Ganoderma lucidum. The naming is messier than it looks. The European species first called Ganoderma lucidum isn’t the same as the East Asian mushroom used in traditional Chinese medicine, which newer research calls Ganoderma lingzhi or Ganoderma sichuanense. When researchers DNA-tested 20 reishi supplements sold in the US, 93% were Ganoderma lingzhi, none contained true European Ganoderma lucidum, and some also held other Ganoderma species.

China’s official pharmacopoeia accepts a second species, Ganoderma sinense, as lingzhi too, and its levels of triterpenes and polysaccharides differ significantly from Ganoderma lucidum. So reishi sold as “black” or another colour may be a different species altogether.

The part used matters as well:

• Fruiting body: the mushroom itself. Most trials used the fruiting body or an extract of it.
• Mycelium: the root-like threads, often grown on grain. The National Cancer Institute notes that mycelium grown on grain also contains alpha-glucans from the grain, whereas fruiting body extracts are made of beta-glucans.
• Spores and spore powder: used in a few trials, mainly in people having cancer treatment.

A good label states the species, the part used and the extract strength. The side effects and cautions below apply whichever name is on the pack. For how reishi sits alongside other mushrooms, see our guides to chaga, turkey tail, cordyceps, lion’s mane and lion’s mane vs reishi vs cordyceps.

Tremella vs reishi

Tremella (Tremella fuciformis), also called snow mushroom or snow fungus, is a different mushroom altogether. It’s an edible mushroom used in Asian cooking and traditional medicine, and in the UK it’s best known as a skincare ingredient. Most of the skin research on it has been done in the lab and in animals.

Human research on tremella is thin: a small Korean trial looked at memory complaints (75 people, 8 weeks) and a small Thai trial looked at people with prediabetes (56 people, 12 weeks). Reishi has more human trials, though still not many. The two aren’t interchangeable, so a tremella product isn’t a reishi product. Our functional mushrooms UK guide compares the main mushrooms side by side.

Reishi vs chaga vs turkey tail

Reishi, chaga and turkey tail are the woody mushrooms people most often compare. None has an authorised health claim in Great Britain, so the table compares research only.

Reishi has the most human research of the three, though it’s still thin; chaga’s is almost all in the lab, and Memorial Sloan Kettering notes its safety and effects haven’t been tested in clinical studies. Read more in our chaga mushroom guide and turkey tail guide, and for a mushroom you cook rather than brew, see shiitake.

Reishi benefits: what the research shows

Reishi has no authorised health claims in Great Britain, so this section describes research only, not what any product does. We’ve rated the strength of evidence by how many people were studied, for how long, and whether the results have been repeated. Low means a few small trials or mixed results; very low means mostly animal or lab research.

The detail behind the table

• Fatigue: a Chinese trial of 132 people with neurasthenia (long-term fatigue) found a reishi polysaccharide extract improved symptoms more than placebo after 8 weeks. A pilot in 48 women having hormone therapy after breast cancer reported less fatigue after 4 weeks of spore powder. Both are single, small studies.
• Stress and wellbeing: in a 30-day trial in 78 female students in India, anxiety, depression, vitality and wellbeing scores improved on 1,000mg a day but not 500mg. A 6-week pilot in women with fibromyalgia, using 6g a day of milled fruiting body, found no statistically significant difference from placebo.
• Immune markers: an 84-day trial in healthy adults aged 18 to 55 found higher counts of some immune cells and natural killer cell activity with a reishi beta-glucan. A 4-week trial in 18 healthy adults and a 12-week trial in 26 adults found no significant change. Changes in blood markers don’t show fewer infections.
• Heart health and blood sugar: the Cochrane review of cardiovascular risk factors (Klupp 2015) included 5 trials and 398 people, mostly with type 2 diabetes, on 1.4g to 3g a day for 12 to 16 weeks. It found no meaningful drop in HbA1c, total or LDL cholesterol, or BMI. One 12-week trial found lower insulin levels but no change in blood pressure. The trials measured risk factors, not heart attacks or strokes.
• Cancer: the Cochrane review (Jin 2016) found too little evidence to justify reishi as a first-line treatment, and none of the 5 trials recorded long-term survival. The reviewers suggested it could be considered as an add-on to standard treatment, never instead of it, but the trials were low quality and any decision belongs with your cancer team.

So what is reishi mushroom good for? On today’s evidence, it’s better described as a traditional evening ritual than a proven remedy: the human trials are few, small and often negative. Weighing it against ashwagandha? See reishi vs ashwagandha. For reishi and skin, see reishi mushroom benefits for skin. For which mushrooms have been tested on inflammation markers, see mushrooms for inflammation, and for menopause, mushrooms for menopause. If you’re after a daytime lift instead, our guide to adaptogens for energy compares the options.

Reishi powder benefits

“Reishi powder” covers two quite different things: ground whole mushroom, and a concentrated extract dried to a powder. The trials above used a mix of forms, so the research on “reishi powder benefits” is the same thin research:

• the fibromyalgia pilot used 6g a day of milled fruiting body (ground mushroom)
• the fatigue trial used 5.4g a day of a polysaccharide extract
• the breast cancer fatigue pilot used spore powder
• the immune trial used a purified reishi beta-glucan

No trial has compared powder with tea or capsules head to head. What we can say is that an extract should state its strength (such as 10:1) or its beta-glucan content, and that the rare liver cases below involved powder taken for one to two months, so stick to the label amount.

Does reishi make you sleepy? Is it calming?

Reishi isn’t a sedative, and there’s no good human evidence that it makes you sleepy. Many people find a warm reishi drink relaxing as part of an evening routine, but that’s a ritual, not a proven effect. Here’s what’s actually known:

• Sleep: when we searched PubMed in October 2026, we found no human trial of reishi with sleep as its main outcome. The sleep research is almost all in animals. Our reishi for sleep guide goes through it, and our deep sleep guide covers the habits with the strongest evidence.
• Does reishi make you tired? Drowsiness isn’t among the side effects listed by the MSD Manual or Memorial Sloan Kettering. In fact, trouble sleeping is listed as a side effect by Memorial Sloan Kettering, and was reported in one cancer trial. If it seems to keep you awake, take it earlier or stop.
• Is reishi calming? Two small trials looked at mood and stress scores. One, in 78 students, found better anxiety and wellbeing scores on 1,000mg a day for 30 days; the other, in women with fibromyalgia, found no clear difference from placebo. That’s too little to call reishi calming. It isn’t a treatment for anxiety, and if anxiety is affecting your daily life, speak to your GP.
• Does reishi lower cortisol? The one human trial we found that measured it, a 12-week study in 26 adults taking 1.44g a day, found no difference in urine cortisol compared with placebo.
• Can reishi cause anxiety? We found no trials reporting this. Dizziness and trouble sleeping are listed as side effects, so stop if it leaves you feeling unsettled.

If you’re building an evening wind-down, our 60-minute bedtime routine and our guide to anxiety at night cover what has better evidence. For stress more broadly, see how to lower cortisol naturally, the best mushrooms for anxiety, ranked by the evidence, and holy basil, a herbal adaptogen with its own small trials.

Reishi side effects

Most people who take reishi have no problems. In a 10-day trial, 16 healthy volunteers took 2g of extract twice a day with no more side effects than placebo, and blood and urine tests stayed normal. Across the longer trials, side effects were usually mild, and there are no reliable figures for how often each one happens. In the Cochrane review of diabetes trials, people taking reishi for four months reported somewhat more side effects than those on placebo, but none were serious and the difference may have been chance.

Reishi tea side effects

Reishi tea has the same possible side effects as other forms, and its bitterness alone puts some people off. The traditional boiled tea has a reassuring track record in one respect: in two of the published liver cases, the patients had drunk boiled reishi without problems and only developed liver injury after switching to reishi powder. Tea from teabags or instant granules varies in strength, so follow the pack.

Reishi and the liver

Is reishi toxic to the liver? Reishi liver toxicity is rare, but it is real. Only a handful of case reports have been published, including one death, and most involved reishi powder taken for one to two months, often alongside other medicines or alcohol. In controlled trials, liver blood tests stayed normal. The published cases:

• Hong Kong (Yuen 2004): liver toxicity in a patient taking a reishi powder formulation.
• Thailand (Wanmuang 2007): a fatal case of sudden, severe hepatitis in 2005. Both this patient and the Hong Kong patient had drunk traditionally boiled reishi without problems, then developed liver injury one to two months after switching to reishi powder. Both were also taking other medicines.
• USA (Guedikian 2023): a 47-year-old man developed acute hepatitis after taking reishi powder alongside alcohol. He was treated in hospital, and his symptoms and blood tests were back to normal at a two-week follow-up.

On the other side of the scales, a 4-week trial in healthy adults found no sign of liver or kidney harm, and an 84-day trial of a reishi beta-glucan found no significant changes in liver or kidney markers. The MSD Manual notes that reishi extract taken for up to a year might be safe, but cautions that the powdered form taken for more than a month could damage the liver.

The NHS lists the signs of jaundice as yellow skin or whites of the eyes, sometimes with itchy skin, darker pee and paler poo than usual.

Medicines, surgery and who should avoid it

Blood thinners and bleeding disorders

Reishi may slow blood clotting. In an older Chinese study, people who took 1g three times a day for two weeks showed reduced platelet clumping. Memorial Sloan Kettering says reishi extracts may prolong clotting test results (INR, PT and APTT). Speak to your GP or pharmacist first if you take a blood thinner such as warfarin, heparin or clopidogrel, use anti-inflammatory painkillers such as ibuprofen or naproxen regularly, or have a bleeding disorder.

Blood pressure and diabetes medicines

Lab and animal research has suggested reishi could lower blood pressure and blood sugar. Human trials have found little effect: a 12-week trial in 26 people with borderline high blood pressure or cholesterol found no change in blood pressure, though insulin levels were lower, and a 16-week trial in people with type 2 diabetes found no change in blood sugar. Even so, if you take blood pressure or diabetes medicines, or already have low blood pressure, check with your pharmacist first and watch for dizziness.

Immunosuppressants and cancer treatment

Because reishi may stimulate parts of the immune system, it may not be safe with immunosuppressant medicines, such as those taken after an organ transplant or for some autoimmune conditions. If you’re having chemotherapy or other cancer treatment, talk to your cancer team before taking any mushroom supplement. Reishi spore powder can also raise a tumour marker blood test called CA72-4, so tell your team if you take it.

Surgery

The MSD Manual warns that high doses before or during surgery could increase the risk of bleeding. If you have surgery planned, tell your surgeon or anaesthetist you’ve been taking reishi and ask when to stop it beforehand.

Pregnancy, breastfeeding and children

Reishi’s safety in pregnancy and breastfeeding hasn’t been properly studied, so avoid it. We don’t recommend our products during pregnancy or breastfeeding. Our products are for adults (18+) only, and we don’t recommend reishi supplements for children or pets.

Is reishi safe to take every day?

For most healthy adults, taking reishi daily at the amount on the label appears to be well tolerated. The trials give a sense of how far that evidence goes:

So the longest controlled trials ran for about four months. Longer daily use hasn’t been studied well. If you take reishi for months at a time, take medicines regularly, or have a long-term health condition, mention it to your GP or pharmacist at your next review.

How much reishi to take, and when

• How much: there’s no official recommended amount in the UK. In the trials above, daily amounts ranged from 500mg to about 6g, depending on whether it was ground mushroom, a concentrated extract or a purified beta-glucan. Because strengths differ so much, follow the label rather than general figures, and don’t go above it.
• How much reishi powder per day? For ground mushroom powder, the trials used up to 6g a day; for extracts, much less. A reishi drink blend contains other ingredients too, so use the serving on the pack.
• Time of day: most people take reishi in the evening, often as a warm drink 30 to 60 minutes before bed. If you find it keeps you awake, move it earlier.
• How long: the trials ran for weeks, so if you’re trying it, give it at least four weeks, and stop if you notice side effects.
• With food: taking it with food or as a drink may help if it upsets your stomach.

Reishi powder vs tea vs capsules vs hot chocolate

No form has been shown to work better than another. The choice comes down to taste, convenience and how clearly the label tells you what you’re getting.

Reishi tea: the traditional method is to simmer dried slices in water for an hour or more, which makes a very bitter brew. Teabags and instant granules are quicker. Our guide to mushroom tea explains how to brew it.

Reishi mushroom powder: either ground whole mushroom or a concentrated extract, and the two aren’t the same. When comparing the best reishi mushroom powder in the UK, look for the species, the part used, the extract strength and a lab test. Prefer something chewable? Our mushroom gummies guide explains why gummies usually hold much less mushroom, and our guide to choosing a mushroom supplement covers labels in more detail.

Reishi capsules: the easiest way to take a fixed amount with no taste. Check whether they contain extract or ground mushroom, and the strength per capsule.

Reishi tincture: a liquid extract taken in drops, usually made with alcohol (often as a “dual extract” with hot water). So each dose contains some alcohol: check the label if you avoid alcohol for health, religious or recovery reasons, and remember that one of the published liver cases above involved reishi alongside alcohol. Our own products are alcohol-free.

Reishi hot chocolate: our Reishi Mushroom Adaptogenic Complex is a reishi hot chocolate made with cocoa, reishi mushroom, maca, cinnamon, coconut sugar and coconut sugar, so it tastes like hot chocolate rather than mushroom. Stir one to two teaspoons into warm (not boiling) milk or water in the evening. It contains a little natural caffeine from the cacao, so if you’re very sensitive to caffeine, have it earlier in the evening; our healthy hot chocolate guide explains how much is in a cup. See also reishi cacao benefits, hot chocolate recipes and our alcohol-free nightcaps.

Pairing it: some people have the reishi drink alongside our Magnesium Glycinate Sleep Complex, which combines magnesium bisglycinate and citrate with L-theanine and botanicals. Magnesium contributes to a reduction of tiredness and fatigue. Others prefer a daytime routine with Flow CBD Oil, a broad spectrum CBD oil with ashwagandha and maca.

The FSA’s 10mg a day figure is precautionary advice rather than a legal limit, set while longer-term safety research continues. At Evopure we think it is a very cautious figure, and many adults use more. If you go above it, increase slowly, and check with your GP or pharmacist first if you take any medication.

iOur products are for adults (18+) only. We don’t recommend our products during pregnancy or breastfeeding. If you take any medication, check with your GP or pharmacist first.

Is reishi legal in the UK?

Yes. Reishi is sold legally in the UK as a food and food supplement. It contains no controlled substances. Choose a product that states the part used (fruiting body or mycelium) and the extract strength, and that’s tested for contaminants. For other mushrooms, see our adaptogenic mushrooms guide.

Related guides

• Reishi is also sold in coffee blends; see is mushroom coffee good for you?
• Reishi and other mushrooms for menopause, and why interactions with HRT haven’t been studied.
• Cordyceps, the mushroom most often taken in the morning for exercise.
• For a mushroom you can cook rather than brew, read our guide to maitake (hen of the woods).
• Taking a break from alcohol? See damp drinking and adaptogen swaps.
• Reishi also turns up in mushroom hot cocoas, for example Four Sigmatic’s Calm Cacao.
• For one brand’s reishi extract label, see our Hifas da Terra guide, which lists the extract and beta-glucan figures it states.
• For a deeper look at each form, see reishi powder vs extract vs tincture vs capsules.
• Reishi also features in multi-mushroom gummies such as Ankhway, where the label lists it alongside nine other mushrooms.
• Our tremella mushroom guide covers snow fungus benefits, skin hydration and side effects.
• Want to brew it yourself? Our reishi tea guide has a step-by-step recipe for dried slices and extract powder.
• Buying on the high street? See what reishi Holland and Barrett sells, with the label maths for its 20000mg capsules.