Is Agaricus Blazei Safe? Side Effects & Liver Questions

Quick answer

Is Agaricus blazei safe? Agaricus blazei is a cultivated edible mushroom with more than a century of documented history (Peck, 1893; Kerrigan, 2005), and in the small human studies done so far, the extract appears to be generally tolerated, with mild side effects, mostly digestive (Hsu et al., 2007; Hsu et al., 2008; Ohno et al., 2011). As with any supplement, a few things are worth knowing — liver effects reported in cancer patients (Mukai et al., 2006), agaritine (Malík et al., 2025), and heavy metals depending on sourcing (Zou et al., 2020) — and some people should check with a healthcare professional first. This page walks through each one so you can choose a quality product with confidence.

We sell an Agaricus blazei supplement. We want you to choose it with good information, so we’ve laid out what the research shows, what to look for in a quality product, and who should check with a healthcare professional first.

Written by the Superfood Science Editorial Team | Reviewed by Dr. Naafila Wiyono, M.D. | Last Updated: 10/21/2026

Agaricus blazei Murill is the commercial name — the one used across the health food trade, on product labels, and throughout the published research. Agaricus subrufescens Peck is the accepted scientific name for the same mushroom. Both refer to one species, and it also goes by Himematsutake, almond mushroom, Royal Sun Agaricus and cogumelo do sol depending on where you are.

That’s an ordinary situation — plenty of foods have a trade name and a botanical name that don’t match. But the history behind these names is genuinely interesting, and it’s older and wider than the version usually told.

A New York market mushroom in the 1890s

The species was first described in 1893 by Charles H. Peck, the New York State botanist (Peck, 1893), from material collected the previous fall — part of it from a crop being commercially cultivated at “Dosoris” (Glen Cove), New York, and part from a grower’s leaf pile in old leaf mold. Peck named it Agaricus subrufescens.

It was known then as the “almond mushroom,” for its marzipan-like fragrance and taste, and it was widely cultivated, sold and eaten in the Atlantic states from at least Massachusetts to Washington, D.C., from the late nineteenth century into the twentieth. Spawn was sold commercially — sometimes under the older American name A. fabaceus, which dates from 1847. It was still reported in cultivation as late as 1918.

Then the market moved. The common button mushroom, Agaricus bisporus, took over American production, and by the early twentieth century the almond mushroom had faded from commerce. It did not disappear — it turns up wild in disturbed ground, most characteristically in piles of leaves, and has been recorded in California, Hawaii, Israel, Taiwan and western Europe.

It also has some genuinely unusual physiology: it is the only Agaricus known to be harmed or killed by prolonged exposure to about 4 °C or lower, and it is remarkably tolerant of high temperatures (Kerrigan, 2005).

The Brazilian and Japanese chapter

Mushrooms from the Atlantic region of Brazil matching the same species began to be cultivated at scale in recent decades, and were marketed primarily in Japan — which is where this mushroom’s modern reputation, and its Japanese name himematsutake (姫松茸), come from. The documented chain:

•    1930 — A. subrufescens is first reported from Brazil, by J. Rick, though his spore measurements don’t match Peck’s species well.

•    February 1973 — a culture is isolated from a collection made at Piedade, São Paulo State, and subsequently cultivated in Japan by Iwade (Heinemann, 1993).

•    The conventional account credits Takatoshi Furumoto, a Japanese immigrant to Piedade, with the find and with sending material to researchers in Japan.

•    1981 — Richard Kerrigan is given that same account in Hiroshima by Mr. Shusuke Minoura, and publishes his conclusion two years later that the Brazilian mushroom then being grown in Japan was “almost certainly” A. subrufescens.

So the mushroom now sold worldwide as Agaricus blazei is a Brazilian population of a species that had been described, named and farmed in the United States eighty years earlier. Same organism, three continents, several names.

Why there are two names

Agaricus blazei Murill entered use for the Brazilian mushroom through Mr. Minoura from 1981, and was formalized in the taxonomic literature by Heinemann (1993). It stuck — and by the time the taxonomy was revisited, decades of published research and an established health-food category were already using it. It remains the commercial and research name, and that is not going to change.

Meanwhile, the taxonomy caught up. Richard Kerrigan’s (2005) revision in Mycologia used DNA sequencing, mating studies and hybrid analysis to show that the Brazilian, Japanese, North American and European populations are all one species — and that Peck’s Agaricus subrufescens, published in 1893, is the oldest validly published name for it, so it takes nomenclatural priority. In strict taxonomic terms, Kerrigan lists A. blazei Murrill sensu Heinemann among misapplied names, because Murrill’s original A. blazei was a different collection.

The practical upshot for a buyer is simple: if a label says Agaricus blazei Murill, the mushroom in the bottle is Agaricus subrufescens Peck. Both names are pointing at the same thing.

The formal synonymy, for anyone checking the literature (Kerrigan, 2005):

Status	Name	Published
Accepted scientific name	Agaricus subrufescens Peck	1893
Synonym	Psalliota subrufescens Kauffman	1918
Synonym	Agaricus rufotegulis Nauta	1999
Synonym	Agaricus brasiliensis Wasser, Didukh, de Amazonas & Stamets	2002
Misapplied (taxonomically)	Agaricus blazei Murrill sensu Heinemann	1993
Misapplied (taxonomically)	Agaricus sylvaticus	some commercial packaging

One detail worth knowing, because product copy often gets it backwards: A. brasiliensis is the newer name, not the older one. It was proposed by Wasser and colleagues (Wasser et al., 2002), who were also reconsidering the A. blazei question; Peck’s 1893 name predates it.

The names you’ll encounter

Name	Where you’ll see it
Agaricus blazei Murill	The commercial name — product labels, the health-food trade, most published research
Agaricus subrufescens Peck	The accepted scientific name
Himematsutake (姫松茸)	Japanese products and research
Almond mushroom	The nineteenth-century American market name, for its marzipan-like aroma
Royal Sun Agaricus	Common English-language trade name
Cogumelo do Sol / “sun mushroom”	Brazilian products
Agaricus brasiliensis	Proposed 2002, now a synonym
ABM	Industry shorthand

Why this matters when you’re comparing products

The naming makes research easy to misread in both directions. Studies published under A. blazei, A. brasiliensis, A. subrufescens, “Royal Sun Agaricus,” and himematsutake are, in the great majority of cases, all studying the same mushroom — so don’t dismiss a paper because the name on it differs from the name on your bottle.

What does change between products, and what matters far more than the label’s Latin: fruiting-body extract, mycelium grown on grain, and whole dried powder are not the same product and don't have the same composition. That’s the comparison worth making.

Is Agaricus blazei safe for your liver? “Agaricus blazei liver damage” is what people search for most, so it goes first.

What’s actually been reported.

A 2006 report from Japan (Mukai et al., 2006) described severe liver dysfunction in three patients with advanced ovarian or breast cancer who were taking Agaricus extract alongside chemotherapy. Additionally, Phase I clinical monitoring noted that a small subset of individuals may experience transiently raised liver enzymes, such as ALT and AST, secondary to an isolated allergic reaction to mushroom products (Ohno et al., 2011).

The important context. The reported cases were in people with cancer, generally undergoing treatment, frequently taking several supplements and medications at once. Liver concerns are not unique to Agaricus blazei; they have been reported with many herbal and dietary supplements, and in those reports it is often hard to pin the problem on a single product. Quality varies, contamination (for example, with toxic metals) and adulteration with undeclared drugs do occur, and people often take supplements alongside prescription drugs, including chemotherapy (Navarro et al., 2017). That is a very different situation from a healthy adult taking a single extract. It does not make the reports irrelevant — it means they can’t be read as “this mushroom damages healthy livers,” and they also can’t be dismissed.

And the research genuinely points both ways. In laboratory animals, Agaricus blazei has looked protective. In rats given carbon tetrachloride — an industrial solvent that researchers use to injure the liver on purpose — the extract reduced signs of damage and raised the body’s antioxidant defenses (Al-Dbass et al., 2012), and other rat work has looked at chemically induced liver toxicity (Barbisan et al., 2002).

In mice fed alcohol for four weeks, a lab-grown form of the mushroom (mycelium cultured in a fermenter, not the fruiting body) led to less visible liver damage under the microscope (Wang et al., 2014). These are chemical-injury models in rodents. They show that the mushroom has a biological effect in animals; they don’t show that it helps people with liver disease.

One small pilot study followed four people with chronic hepatitis B who took 1,500 mg of extract a day for 12 months (Hsu et al., 2008). Their liver enzymes — ALT and AST, blood markers that rise when liver cells are damaged — fell in all four, and no side effects were reported. But there were only four participants, everyone knew they were taking the extract, there was no comparison group to show what would have happened without it, and one participant also had hepatitis C. That makes it an idea worth testing properly, not evidence that the extract works.

What we recommend:

•    If you have any liver condition, don’t take it without consulting your healthcare professionals.

•    If you are being treated for cancer, don’t take it without telling your oncology team. Not “ask if it’s okay” — tell them specifically what you’re taking, at what dose, so it’s on your chart alongside your treatment.

•    If you take anything that’s hard on the liver, or several supplements at once, talk to your qualified health care professional. Taking several products at once makes it harder to tell which one is responsible.

•    If you have labs coming up, mention it. A raised enzyme reading is easier to interpret when your doctor knows what you’re taking.

What it is. Agaritine is a naturally occurring amino acid found across the Agaricus genus — including Agaricus bisporus, the ordinary white button mushroom in every supermarket. It contains a hydrazine group, and hydrazines as a chemical class have raised toxicological questions, which is why Agaricus blazei toxicity comes up.

What the evidence shows. Less than the internet suggests, in both directions. A 2025 review of agaritine (Malík et al., 2025) concluded that research has focused on its possible role as a pro-carcinogen, that some studies found no evidence of toxic effects, and that safe consumption levels for humans have not been established. A mouse study from 1984 found no carcinogenicity by subcutaneous administration (Toth & Sornson, 1984); other work has examined genotoxicity and DNA binding with mixed results. Agaritine is heat-sensitive and degrades with cooking, drying and processing.

What Japan’s food-safety regulators found. In 2006, Japan’s health ministry asked the Food Safety Commission of Japan, an independent expert panel, to assess Agaritine in Agaricus blazei products, which had become popular health foods in Japan.

The panel concluded that while test-tube studies showed some potential warning signs, comprehensive follow-up testing in living animals across multiple organs showed no signs of DNA damage or harmful genetic mutations. Because of this, both the Agaricus product and agaritine itself were determined not to pose any real-world genetic safety concerns in the body (Food Safety Commission of Japan, 2009).

What we recommend:

•    Use hot-water-extracted products over raw mushrooms. Agaritine degrades with heat and processing, so an extract is the lower-exposure form.

Laboratory samples of Agaricus have been found to contain inorganic arsenic, depending on soil and cultivation substrate composition (Zou et al., 2020). Whether that has caused harm in people isn’t established, but it’s a real finding and it’s the one safety issue on this page that is entirely within a manufacturer’s control.

Mushrooms accumulate what’s in their growing substrate. Heavy metals in the substrate end up in the mushroom. The quality of substrate and soil is critical. This is largely a sourcing problem, not an inherent property of the species. It also applies differently to different forms of the mushroom: fruiting body, mycelium, extracts, and whole dried powder are not the same product, and organic cultivation on controlled, tested substrates lowers the chance of picking up environmental contaminants compared with open-soil or unmonitored growing.

What we recommend: buy from a company that publishes a current certificate of analysis including heavy metals and will send it to you if it isn’t on the site. If a seller can’t produce one, that is the answer to your safety question.

Superfood Science Agaricus Bio 600mg contains Agaricus blazei Murill with low heavy metals and high beta-glucans. It combines organic fruiting body and mycelium, grown on controlled agricultural inputs. You can click here to review a 3^rd party laboratory test result for arsenic. The certificate of analysis (COA) reports that the analytical result was not detected, with a limit of detection of 0.015 ppm for the particular lot. The same third-party testing covers cadmium, lead, and mercury as well as arsenic (measured by ICP-MS), along with microbial pathogens.

So, is Agaricus blazei safe? Standard natural product databases describe oral Agaricus extract as possibly safe when taken for up to 12 weeks, and whole mushroom powder for up to 6 months (RxList, n.d.). Long-term clinical studies in cancer survivors in remission also show that it is generally well tolerated over 6 to 12 months of daily use (Ohno et al., 2011; Hsu et al., 2008).

The Agaricus blazei side effects that do get reported are mostly mild (Ohno et al., 2011):

•    Stomach discomfort

•    Diarrhea

•    Nausea

Less commonly reported, in individual case reports:

•    Cheilitis — inflammation and swelling of the lips, reported as a rare allergic reaction (Memorial Sloan Kettering Cancer Center, n.d.)

•    Raised liver enzymes (see above)

Mild digestive upset most often settles if you take it with food or start at a lower amount. If it doesn’t settle, stop.

Agaricus blazei contraindications, in plain terms — do not take it if:

You are allergic to mushrooms	Straightforward cross-reactivity risk
You are pregnant or breastfeeding	There isn’t enough reliable safety information. Avoid.
You have surgery scheduled	At least two weeks, because of the possible effect on blood sugar (RxList, n.d.)

 

Talk to your doctor first if:

You take diabetes medication	Agaricus may lower blood glucose. This is rated a moderate interaction — combined with glucose-lowering drugs it could push blood sugar too low. Monitor closely.
You take any prescription medication	In laboratory studies Agaricus extract showed weak inhibition of CYP3A4 (Engdal & Nilsen, 2009), an enzyme that metabolizes a large share of common drugs. Clinical relevance hasn’t been determined, but CYP3A4 is the pathway behind many real interactions — worth a pharmacist’s five minutes.
You have an autoimmune condition or take immunosuppressants	An ingredient marketed for immune support warrants a conversation if your treatment plan involves deliberately suppressing immune activity. We’re not aware of specific evidence of harm here; we flag it because the mechanism makes it a reasonable question.

The amount most commonly used is 600 mg capsule by mouth, two times daily, or 1 ml of liquid extract, two to three times a day. That reflects common practice rather than a dose established for any specific purpose. Some people choose the hot-water liquid extract over capsules because they find it easier on a sensitive stomach, which is relevant given that the side effects reported most often are mild digestive ones.

Clinical studies on Agaricus blazei Murill have used 1.5 grams to 5 grams daily.

Published human clinical studies have looked at insulin resistance, natural killer cell activity, and quality of life in cancer patients receiving chemotherapy, and liver function in hepatitis B (Ahn et al., 2004; Hsu et al., 2007; Hsu et al., 2008).

Consult with your healthcare professionals about different dosages to meet your health goals. For the research on potential benefits, see our companion piece, Royal Sun Mushroom Benefits: Evidence, Safety & Tips.

Does Agaricus blazei cause liver damage?

The liver problems reported with Agaricus blazei have been in people with cancer, not healthy adults. The published reports of severe liver dysfunction involve people who were taking Agaricus products during chemotherapy and other medications, which are themselves well-known causes of liver injury, so it is hard to tell which was responsible. A link to the mushroom has been suggested but not established. On the other side, animal studies have reported protective effects against chemically induced liver injury, and a small pilot study in four people with chronic hepatitis B saw liver enzymes improve over 12 months (Hsu et al., 2008). Human evidence is still limited, so if you have a liver condition or take chemotherapy or other medications, talk with your healthcare professional before using it.

Can I take Agaricus blazei with my medication?

Ask a pharmacist. In laboratory studies, it weakly inhibited CYP3A (Engdal & Nilsen, 2009), an enzyme involved in metabolizing many common drugs, and it may lower blood glucose — a moderate interaction with diabetes medication (RxList, n.d.).

Is Agaricus blazei safe during pregnancy or breastfeeding?

There isn’t enough reliable information. Avoid it.

How long before surgery should I stop?

At least two weeks, because of the possible effect on blood sugar (RxList, n.d.).

There is also a theoretical concern about clotting, based on a laboratory finding with a fermented Agaricus blazei wine (Firenzuoli et al., 2008), so if you take a blood thinner such as warfarin, aspirin, or clopidogrel, check with your doctor or pharmacist first.

Is Agaricus blazei the same as Agaricus subrufescens?

Yes. Agaricus blazei Murill is the commercial name used on labels and in most published research; Agaricus subrufescens Peck, published in 1893, is the accepted scientific name for the same mushroom. It also goes by himematsutake, almond mushroom, and Royal Sun Agaricus. All of these are different from the common button mushroom, A. bisporus.

Was Agaricus blazei discovered in Brazil?

The Brazilian chapter is the one that made it famous, but it isn’t the beginning. The same species was described and commercially cultivated in the eastern United States in the 1890s as Agaricus subrufescens, sold as the “almond mushroom.” A Brazilian population was collected at Piedade, São Paulo State, in 1973 and taken into cultivation in Japan, where it gained a reputation as a medicinal mushroom and received its Japanese name, himematsutake.

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