Chronic Urticaria (Hives) and Mushroom Allergy: What Was Measured, and What About Antihistamines

Chronic urticaria (hives) is a mast cell–driven, sometimes autoimmune skin disease, and everyone living with it asks about every supplement — reishi (Ganoderma lucidum, lingzhi), lion’s mane, cordyceps — “could this make it worse?” Honest answer: no study has tested any of our four mushrooms in urticaria. In humans, the reverse was measured: spores of a reishi relative, not reishi itself, are an allergen: 44% of asthmatics reacted on skin testing. With antihistamines or omalizumab (Xolair): no combination study found.

The kinds of evidence that do exist, from closest to a person to furthest away: on the disease itself — an international guideline, a phase 3 trial of omalizumab and meta-analyses of antihistamine updosing; on mushroom allergy — skin tests in two studies, case reports of anaphylaxis from edible mushrooms, and case series of shiitake dermatitis; on our mushrooms — isolated rash and anaphylaxis with lion’s mane, itching in 3% of reishi users in a survey, and mice and rats in which reishi reduced itching or histamine release. On the combination “mushroom × urticaria” we found nothing. This page is built around what you are asking, not around what the market is selling. The broad picture of mushrooms and autoimmune disease is gathered on the parent page on medicinal mushrooms and autoimmune disease; here we deal with the specific junction of skin, allergy and drugs.

Do medicinal mushrooms help with chronic urticaria — what was actually tested?

Nothing. Reishi, lion’s mane, cordyceps and turkey tail have not been tested in urticaria — not in a human trial, not in an animal with the disease, and not in patients’ cells. A direct search for reishi with urticaria returns 0 records in PubMed. What has been measured in humans is the reverse direction: allergy to Ganoderma spores — of a reishi relative, and of reishi itself — and isolated skin reactions to mushrooms.

To understand what that “0” means, it helps to know the disease. According to the international guideline, updated by a consensus of 64 delegates from 50 societies in 31 countries, urticaria is a “mast cell–driven disease” that presents as itchy wheals, as deep swelling (angioedema), or both, and its chronic form “impairs quality of life and performance at work and school”. At any given moment it affects 0.5–1% of the population, with a peak at ages 20–40, and in most patients no cause is identified. This is a disease with large randomized trials — but every one of them is a trial of a drug.

So this page is not built around “which mushroom helps hives”. It is built around three real questions: can a mushroom trigger an allergy or a rash (here there are data), can it be combined with the drug you already take (here there are none), and what was measured on the things you live with — itching, broken sleep and stress.

What was measured, in which system — and what came out?

The table sorts the questions you ask by what was measured on them and in which organism. The “mushroom × urticaria” rows are empty. The drug rows contain trials of the drug alone. And the rows with human data on our mushrooms are mostly the risk rows — spore allergy, rash, itching and a single case of anaphylaxis — plus the cyclosporine row, from kidney-transplant recipients.

Is there such a thing as an allergy to medicinal mushrooms — and what are the numbers?

Yes, and in humans. Among 33 people with asthma or rhinitis, 30% reacted on skin-prick testing to spores of Ganoderma applanatum — more than to grass (27%) and slightly fewer than to house dust mite (36%); in the asthma subgroup — 44%, exactly as for mites. On reishi itself: 28.48% of 172 respiratory-allergy patients in Delhi reacted to the spore extract.

This is the chapter this page exists for, and it gets the full space. What was measured. In a 2011 study, “in a tropical environment”, 33 people with asthma or rhinitis underwent skin-prick tests with crude spore extracts of three basidiomycete fungi, alongside commercial allergens. Ganoderma came second, and IgE levels matched the positive reactions — in other words, this is true allergic sensitization, not irritation. ⚠️ The caveat that has to be said: the species tested was G. applanatum, a relative of reishi from the same genus, not G. lucidum. On reishi itself there is an older study: in Delhi, between October 1989 and September 1991, up to 336 spores per cubic meter were counted in September, and on intradermal testing 28.48% of 172 patients reacted to the spore extract and 17.44% to the extract of the mushroom body; more than 80% of those who tested positive had elevated IgE. Modern monitoring in Poland found that the spore season is stronger in the countryside than in the city, and that during periods of high concentration “allergy and asthma symptoms may appear in allergic people”.

Why this does not carry over automatically to the bottle. Both studies measured spores in the air and on the skin — not the swallowing of an extract. We found no study of what happens when a person sensitized to Ganoderma spores swallows a fruiting-body extract. What can be known today: reishi is not “safe because it is natural”; it is a mushroom, and mushrooms are a recognized allergen. We laid out the respiratory side on the lungs page. What to ask the allergist: “I have a sensitivity to mold or mushrooms — is it worth testing for Ganoderma sensitivity before I start a supplement?”

Edible-mushroom allergy — does it tell you anything about reishi?

Perhaps, and nobody has measured. Allergy to edible mushrooms exists and is rare: a 2024 review gathered 28 cases of anaphylaxis, more than a third of them from button mushrooms. In some of the subjects, cross-sensitivity between several mushrooms was found, “without a clear and consistent pattern”. Reishi, lion’s mane and cordyceps were not tested in any of these cases.

“Edible mushroom allergy” is Google’s first completion for “mushroom allergy”, so it gets an answer here. The case that opened the review: a 77-year-old woman with no allergic history who developed anaphylaxis with a drop in blood pressure after a mushroom omelet. On skin testing she reacted to cooked button mushroom — and also to portobello, shiitake, oyster mushroom and enoki. In the other 27 cases in the literature the mean age was 28.8, with 14 from Europe and 12 from Asia. Another case shows how a bridge between allergies forms: a 38-year-old man with a mold allergy developed generalized urticaria and anaphylactic shock immediately after eating button mushrooms, and the researchers showed that one of the mushroom’s enzymes resembles a mold allergen closely enough for the body to confuse the two. “Previous sensitization to mold may explain severe food reactions,” they wrote.

What this means for you: if you are allergic to edible mushrooms or to mold, “mushroom extract” is not a category that is safe in advance — and there is no study that can tell you whether your sensitivity carries over to reishi or lion’s mane. That is exactly a question for an allergist, who can run a skin-prick test with the specific mushroom. And on cordyceps there is one record: the title of a 2010 letter describing five cases of food allergy to wild cordyceps — the kind that grows on a caterpillar — with cross-reaction to silkworm pupae. No abstract, no details; but if you are allergic to insects in food, that is a detail your doctor needs to hear.

What is “shiitake dermatitis” — and what does it have to do with beta-glucan?

It is an itchy rash, in streaks like whip marks, that appears a day or two after eating raw or undercooked shiitake. In France, 59 cases were documented over six years; in a worldwide review — 50. The presumed cause is lentinan, shiitake’s beta-glucan polysaccharide, which breaks down with heat. Antihistamines and steroids showed no proven benefit in it.

Google completes “shiitake mushroom allergy”, so precision is due: this is probably not a classic allergy at all. At the French poison control centers, between 2014 and 2019, out of 125 shiitake exposures, 59 cases of dermatitis were identified at ages 19–69: papules and urticarial plaques in streaks on the trunk, arms and legs, appearing 1 to 168 hours after the meal (median 48) and lasting a median of 10 days. The more people ate, the longer it lasted — 4, 7 or 15 days, a significant trend. Of the patients, 38 received steroids, antihistamines or both “with no proven benefit”, and all of them recovered. In the systematic review of 50 cases: streaks in 98%, itching in 78%, spontaneous recovery in about 12.5 days.

And the connection to us, honestly. Lentinan is a beta-glucan — the same chemical family we measure in the bottle. But it is shiitake’s beta-glucan, which breaks down with heat, and the reaction appears after eating the raw mushroom. Nothing can be inferred from it about the beta-glucan of reishi, lion’s mane or cordyceps — neither for better nor for worse. What we did check: searching our four mushrooms together with urticaria or dermatitis turned up no parallel to shiitake dermatitis. “Not found” is not “does not happen” — but that is what there is.

Lion’s mane, reishi and cordyceps — what is documented on rash, itching and anaphylaxis?

Little, and not zero. With lion’s mane: one case of anaphylaxis after eating the fresh mushroom, and three in the mycelium arm (plus one on placebo) who dropped out of a 49-week trial in mild Alzheimer’s patients because of abdominal discomfort, nausea and rash. With reishi: itching in 3% of 1,374 users in a survey with no control group. With cordyceps: food allergy in five cases, known from a title only.

Lion’s mane. A 2024 clinical review sums up that it “appears safe and inexpensive as a powder or capsule — but one case of anaphylaxis has been reported after a patient ate fresh lion’s mane”. A 2025 systematic review lists “allergic reactions” among the possible side effects, “although generally not reported”. The NIH LiverTox database notes at least one report of an acute hypersensitivity reaction to lion’s mane taken by mouth, and adds that it “has not undergone prospective safety trials”. In the 49-week trial of an erinacine A-enriched mycelium, in mild Alzheimer’s patients — elderly people on multiple drugs — three in the mycelium arm withdrew because of stomach discomfort, nausea and a skin rash, and one in the placebo arm because of nausea; the authors themselves write that establishing causality “remains a challenge”. A trial whose researchers are employed by Grape King Bio, the manufacturer. Reishi. In the largest cross-sectional survey, 9.1% of 1,374 cancer patients reported a side effect, including itching in 3%; in a Cochrane review, people taking reishi had a 1.67-fold risk of any side effect — not significant and not serious. And there is a 2013 case report whose title describes blistering dermatitis of the hands and hair loss during an aplastic crisis attributed to reishi — with no abstract in PubMed, so we will not go beyond the title. These cases are rare, and they join the list on the “who shouldn’t take reishi” and “who shouldn’t take lion’s mane” pages.

What this means for anyone living with urticaria. In your case it is actually harder to tell: if wheals appear almost every day anyway, a new supplement can hide inside the noise. The only way to know is a diary — when you started, and what changed in your itch score and in the number of wheals. A flare after a new supplement — stop and tell your doctor; swelling of the lips or tongue, or shortness of breath — the emergency room, not the diary. The overall picture of side effects is gathered on the side effects page.

“Reishi is a natural antihistamine” — what exactly was measured?

Three things, none of them in a human. Triterpenes from reishi inhibited histamine release (1985, title only); an extract of the culture medium inhibited histamine release from rat mast cells — and the active substance was oleic acid; and in mice, a reishi extract reduced allergic itching — but mast cells and H1 receptors “are not the main site” of that action. In urticaria: 0.

What the market claims. “Reishi blocks histamine”, “reishi stabilizes mast cells”, “a natural antihistamine”. On seasonal allergy and hay fever we wrote a separate page — reishi and seasonal allergies; here we will go through what concerns the skin.

What exactly was measured. In 1985 a paper was published under the title “histamine release-inhibitory triterpenes” from reishi — with no abstract in PubMed, and therefore with no system and no number that can be quoted. In 1988 Japanese researchers took the culture medium in which the mushroom had been grown, and showed that a chloroform extract of it inhibits histamine release from rat peritoneal mast cells; the active substance they isolated was oleic acid, at a concentration of 5–50 micromolar — the fatty acid of olive oil. And in 2010, in mice sensitized to mosquito saliva, a methanol extract of reishi at 100 and 300 mg/kg reduced itching — but, unlike an antihistamine, it did not stop fluid from leaking into the skin, and the authors wrote explicitly that “mast cells and H1 receptors are not the main site” of its action. There is also a 2014 review titled “suppression of inflammatory and allergic responses” by reishi — a review of mechanisms and of patents, which is quoted online as though it had shown a benefit in patients.

Why this does not carry over to a person. Oleic acid from a culture medium is not a fruiting-body extract; rat mast cells in a dish are not human skin; and a mouse scratching because of mosquito saliva is not chronic urticaria, in which wheals appear with no trigger at all. What can be known: that the word “antihistamine” does not fit even the mouse data. What to ask the doctor: not “can reishi replace my fexofenadine” — but “is there any reason to add something, and how will we know if it is doing harm”.

Taking fexofenadine (Allegra), desloratadine (Clarinex) or bilastine — can you take mushrooms with them?

Not measured — 0 studies of a mushroom with any antihistamine. What is known: fexofenadine (Allegra) is barely broken down by the liver, but its absorption is sensitive to food — grapefruit juice cut exposure to it from 1,954 to 1,063 units. Reishi inhibited liver enzymes in rats; in human microsomes — weakly. The decision belongs with the pharmacist.

What is known about the drugs. Non-sedating H1 antihistamines are the mainstay of treatment, but at the licensed dose they give effective relief to fewer than 50% of patients; guidelines allow the dose to be raised up to 4-fold. A meta-analysis of 15 papers found that 63.2% of non-responders responded to updosing — but the significant improvement was in itching, not in the number of wheals, and the authors caution that the studies are weak. That is the context of the search completion “fexofenadine not working”: the next step is with your doctor, not in a bottle.

What a measured interaction looks like. Fexofenadine is absorbed with the help of transporters in the gut. In 48 healthy volunteers, the area under the curve for fexofenadine taken with water was 1,954 ng·h/mL — and with grapefruit juice 1,063; the peak concentration fell from 453 to 253. A systematic review ranks it among the three drugs most sensitive to this kind of interaction, and writes that apple, grapefruit and orange juice reduce exposure to such drugs by about 85%. In the same study, incidentally, 41 celiac patients absorbed fexofenadine just as healthy people did. And rupatadine — another antihistamine — must not be combined with enzyme inhibitors such as erythromycin or ketoconazole, because its blood level rises — although no clinically relevant adverse events were reported there. What is known about the mushrooms. A reishi polysaccharide inhibited CYP3A, CYP1A2 and CYP2E1 in rat liver microsomes; in human microsomes, on CYP3A, a reishi extract was weak — an IC50 above 10 micrograms per milliliter. On fexofenadine’s gut transporters — no data on any mushroom. On desloratadine (Clarinex) or bilastine with a mushroom — 0.

The wording we can stand behind: some antihistamines are sensitive to what is swallowed with them, and mushrooms have not been tested against them — so this is a question for the pharmacist. Not “dangerous to combine”, not “safe to combine”. What to bring to the pharmacist: the name of the antihistamine, the dose (especially if it has been raised), the name of the supplement, and when you take each one. The wider list is on the drug interactions page.

And with omalizumab (Xolair)?

Not tested: a search for reishi with omalizumab returns 0 records. Omalizumab (Xolair) is an anti-IgE antibody given by injection, and in a phase 3 trial of 323 patients it lowered the weekly itch score by 9.8 points at 300 mg, versus 5.1 on placebo. The mushroom question here is not about liver enzymes — it is about the immune system.

The trial that brought omalizumab to urticaria, published in 2013, enrolled 323 patients who remained symptomatic despite antihistamines. Three injections 4 weeks apart; a baseline weekly itch score of about 14 out of 21. At week 12: placebo −5.1, 75 mg −5.9 (not significant), 150 mg −8.1, 300 mg −9.8. Serious adverse events — 6% at 300 mg versus 3% on placebo. Funding: Genentech and Novartis. Note the placebo figure: a five-point drop with no drug at all. That is the bar any supplement claim has to clear, and no mushroom has been measured against it.

Why there is no enzyme axis, and still a question. An antibody is a protein; it does not pass through the liver enzymes that reishi inhibited in a dish. But omalizumab acts on the immune system, and mushrooms change immune markers in humans — see the autoimmunity chapter below. Does that change anything alongside an anti-IgE injection? Nobody has checked. What to ask the doctor: “I am considering a supplement that raises immune markers — does that matter for my treatment?”

Cyclosporine for resistant urticaria — and what is known about cordyceps?

Here there actually are human data — but not from urticaria. In kidney-transplant recipients who received cordyceps, cyclosporine doses and trough blood levels were significantly lower — the doses were set by the doctors according to blood levels, and no mechanism was measured. In urticaria, cyclosporine is an advanced line of treatment, and its combination with a mushroom has not been tested. This is not a decision to make on your own.

More than 25% of people with chronic urticaria are resistant to antihistamines even at high doses, and omalizumab and cyclosporine control the disease in two-thirds of them. In a 2023 network meta-analysis of 7 trials and 410 participants, cyclosporine plus an antihistamine gave the largest improvement in activity score of four immunosuppressants. And in a completely different world — kidney transplantation in China — cyclosporine was given together with cordyceps on purpose: in 202 recipients, 1 gram three times a day, cyclosporine doses were significantly lower in months 2–6 and trough blood levels in months 3–6. ⚠️ The caveat: the doses were set by the doctors according to blood levels, and the abstract reports only that doses and trough levels were lower — no mechanism; the authors write only that cordyceps “may allow” a lower dose. So “cordyceps lowers cyclosporine levels” cannot be stated as fact. What can be said: this is a combination that was given under blood monitoring — and anyone taking cyclosporine for urticaria does not add cordyceps without their doctor.

Chronic urticaria is an autoimmune disease — so what does that mean for “boosting immunity”?

In some patients, yes. People with chronic urticaria are 5.18 times more likely to carry thyroid antibodies, and Hashimoto’s appears in 5% or more of them. And in healthy adults, beta-glucan from reishi raised CD3, CD4, CD8 and NK cells — a measurable stimulation. What that stimulation does in autoimmune urticaria — nobody has measured.

The disease side. A 2017 systematic review found that autoimmune diseases are more common among people with chronic urticaria: 1% or more for type 1 diabetes, rheumatoid arthritis, psoriasis and celiac disease; 2% or more for Graves’ disease; 3% or more for vitiligo; 5% or more for Hashimoto’s and pernicious anemia; and more than 15% have a family history. A meta-analysis of 19 studies — 14,351 patients versus 12,404 controls — found a 5.18-fold risk of TPO antibodies, and 6.72-fold in the high-quality studies. Another review states, as “strong evidence”, that chronic urticaria can improve with levothyroxine or thyroid treatment. If you also have Hashimoto’s, the Hashimoto’s and levothyroxine page deals with the absorption question there.

The mushroom side. “Immune-boosting” is a marketing word; what was measured is one direction. In a randomized trial in healthy adults aged 18–55, over 84 days, purified beta-glucan from reishi raised CD3, CD4, CD8, the CD4/CD8 ratio and NK cells; and there was a significant difference in IgA and in NK cytotoxicity (direction not stated in the abstract). In cancer patients, Cochrane calculated a rise of 3.91% in CD3, 3.05% in CD4 and 2.02% in CD8. And there is a precedent — not with mushrooms: three patients whose autoimmune skin disease (pemphigus and dermatomyositis) appeared or flared shortly after taking immune-stimulating supplements — echinacea and spirulina. What is not known: a single report of an autoimmune flare from one of our four mushrooms — we did not find one; but adverse-event reporting for supplements is largely voluntary, so the absence of a report is not a safety certificate. The reverse does not hold either — there is no evidence that they cause flares. On the difference between “modulating” and “boosting” we wrote in reishi and the immune system.

What was measured on itching, on the sleep it steals, and on stress?

On itching in urticaria — no mushroom has been measured. On sleep — there is not a single randomized trial of reishi in humans. On fatigue — reishi lowered it by 28.3%, but placebo lowered it by 20.1%. And on stress — lion’s mane reached p=0.051, not significant. Urticaria takes a toll on all four, and none of them was measured in people with urticaria.

What urticaria does to sleep. In 673 adults whose disease had lasted a year or more despite treatment, “chronic urticaria substantially interfered with sleep and daily activities”; 66% had also had angioedema attacks in the past year. A review of the global burden lists severe itching as a cause of sleep disturbance, and anxiety and depression in more than 30% of patients. That is the context of the search completions “urticaria at night” and “urticaria stress”.

What was measured on the mushrooms. Sleep: all of reishi’s marketing leans on it, and there is not one randomized human trial of it — we laid that out on the reishi for sleep page. Fatigue: the cleanest trial — 132 patients with neurasthenia, 1,800 mg three times a day, 8 weeks — found a 28.3% drop in the sense of fatigue versus 20.1% on placebo; the real difference is about eight percentage points, in a different population. Stress: in 41 healthy young adults, 1.8 grams of lion’s mane for 28 days, subjective stress fell at p=0.051 — the authors themselves call it a “trend”. And itching: the only data point we found is the mice with mosquito saliva from the previous chapter. What can be known: that the broken nights of urticaria are a medical problem that is handled by getting the disease under control, and that no mushroom has a number on it. On reishi and stress we wrote in reishi for anxiety and stress.

What happened when reishi was tested in a population with chronic symptoms?

At the high dose, symptom severity was higher than on placebo (p=0.012); at the low dose — no change. That is what came out of a pseudo-randomized crossover trial in 29 men with Gulf War Illness (low dose versus placebo: p=0.603). This is not urticaria and not an autoimmune flare — it is a different population, with fatigue, pain and a neuroinflammatory component.

The 2021 study tested two plants and one mushroom in 29 men with Gulf War Illness: 30 days of baseline, 30 days of placebo, 30 days of a low dose and 30 days of a high dose for each plant. The authors’ conclusion, word for word: reishi “may increase symptoms in some sufferers” — and next to it, “results from a small sample, preliminary”. There is a detail here that is hard to ignore on a page about hives: the second plant in the trial was stinging nettle (Urtica dioica), and at the high dose it lowered symptom severity (p=0.048). We do not sell nettle, and we infer nothing from it about urticaria — it is only a reminder that in the same trial, the mushroom’s numbers went the other way.

Why it is on this page. Because it is the only human answer we found to the question “can reishi make me worse” in a population with a chronic multi-system illness. It does not carry over automatically to urticaria — but it is enough to make sure nobody writes “reishi cannot do harm”. What can be known: that dose matters, and that a response to a supplement is measured on yourself, in a diary, not in an advertisement.

What we actually measure in our bottle

After a page that is mostly “not measured”, you deserve to know what was measured — and on what. We grow the mushrooms ourselves, on a farm in the Galilee: fresh fruiting body, not mycelium grown on grain and not imported powder. The mushroom goes from harvest straight to extraction, with no drying step in between; as far as we know, we are among the few in the world who work this way. The extraction is triple, and its alcohol stage runs for 7 weeks. Extraction ratios on a fresh-mushroom basis: reishi 1:3, lion’s mane 1:2 and cordyceps 1:2.5. Alcohol in the finished extract: 32% — a figure worth bringing to the pharmacist together with the names of your drugs.

And on a page about allergy, one thing needs to be said explicitly: we grow reishi, and reishi releases spores — the same allergen that was measured in Delhi. We do not hide that; what goes to the lab is the finished extract. We sent it for testing at TÜV Austria, and what came back is the beta-glucan percentage on a dry-matter basis — and alongside it alpha-glucan, meaning starch, which was not detected in any of them. Alpha-glucan not detected is the chemical proof that there is no grain in the bottle — and that is also relevant to anyone who has urticaria together with celiac disease, as we laid out on the celiac page. To understand why this matters, it helps to know the market’s three-step ladder: mycelium grown on grain, where beta-glucan is usually below 7% and most of the weight is starch; imported dried fruiting body; and fresh fruiting body from the farm. Why beta-glucan and not “total polysaccharides” — we explained separately.

All our tests are public, and anyone who wants to read the report themselves will find our explanation of how to read a COA. Kosher certification — Mateh Yehuda Rabbinate, Rabbi Gad Atias. We have no allergen testing of the extracts, so we will not write “hypoallergenic”. That is what we know how to measure and prove about what is in the bottle. What it will do for urticaria was not measured — so it is not written.

What this page does not say — and what we do not claim

We do not claim that reishi, lion’s mane, cordyceps or turkey tail relieve urticaria, reduce itching or wheals, or act as a “natural antihistamine” — none of them has been measured in urticaria, in any organism. We do not claim the opposite either — that they make urticaria worse: that was not measured. We do not claim that someone allergic to Ganoderma spores will react to a swallowed extract, nor that they will not. We do not claim that combining with fexofenadine, desloratadine, bilastine, omalizumab (Xolair) or cyclosporine is dangerous — nor that it is safe; none of them has been tested in urticaria. We do not claim that shiitake dermatitis says anything about our beta-glucan. And we do not deal here with military medical profiles, National Insurance benefits or disability ratings — Google completes them for chronic urticaria, but we have no expertise in them and no sources on them. What we do say: chronic urticaria is managed by a dermatologist or an allergist; anyone taking an antihistamine at an increased dose, a biologic injection or an immunosuppressant talks to the doctor or pharmacist before any supplement, including ours. And anyone allergic to mushrooms or to mold starts with the allergist, not with us. Under DSHEA, a dietary supplement may not claim to diagnose, treat, cure or prevent any disease.

The bottom line

Reishi, lion’s mane, cordyceps and turkey tail have not been tested in chronic urticaria — not in humans, not in animals, not in patients’ cells. What has been measured in humans is the reverse direction: Ganoderma spores are an allergen, with a 44% skin reaction among asthmatics to a related species and 28.48% among respiratory-allergy patients to reishi itself; and lion’s mane has been documented in one case of anaphylaxis and in a rash within a trial. “Reishi as an antihistamine” rests on rats and mice, and even there the mechanism is not an antihistamine one. With fexofenadine, desloratadine and omalizumab (Xolair) — zero combination studies that we found; cyclosporine + cordyceps was measured only in kidney-transplant recipients, not in urticaria — and the question belongs with the pharmacist. And if someone sells you a mushroom “for hives” — send them this page, and go to an allergist.

Frequently asked questions

Does reishi help with chronic urticaria?

Not measured — in any human or any animal with the disease. A search for reishi with urticaria returns 0 records in PubMed. What exists is inhibition of histamine release from rat mast cells and suppression of itching in mice — and there the authors write that mast cells and H1 receptors are not the main site. On urticaria itself there is not a single data point.

Is there such a thing as an allergy to medicinal mushrooms?

Yes. On skin testing, 30% of 33 people with asthma or rhinitis reacted to spores of Ganoderma applanatum — a close relative of reishi — and 44% of the asthmatics among them. On reishi itself: 28.48% of 172 respiratory-allergy patients reacted to the spore extract. These are spores on the skin and in the air, not a swallowed extract — on which there is no study. Sensitive to mold or mushrooms: see an allergist first.

I’m allergic to edible mushrooms. Can I take reishi extract?

No study answers that. In a review of 28 cases of anaphylaxis from edible mushrooms, cross-sensitivity between several kinds was sometimes found, but “without a clear and consistent pattern”, and reishi was not tested in any of the cases. That is exactly a question for an allergist, who can test the specific mushroom with a skin-prick test before you try it.

Can I take reishi with fexofenadine (Allegra)?

Not measured — a question for the pharmacist. Fexofenadine is barely broken down by the liver, but its absorption is sensitive to what is swallowed with it: grapefruit juice cut exposure to it from 1,954 to 1,063 units. On any mushroom with any antihistamine — 0 studies. Bring the pharmacist the name of the drug, the dose and the name of the supplement.

And with omalizumab (Xolair)?

Not tested: reishi with omalizumab — 0 records. Omalizumab is an antibody that does not pass through liver enzymes, so the interaction question is not an enzyme question but an immune one: mushrooms raise immune markers in humans, and the injection acts on the immune system. What the two do together — nobody has measured. A question for your treating physician.

What is the rash some people get after shiitake?

Shiitake dermatitis: itchy red streaks, like whip marks, a day or two after raw or undercooked shiitake. In France 59 cases were documented over six years, and all of them recovered within days to weeks. The presumed cause is lentinan, a shiitake polysaccharide that breaks down with heat. There is no documented parallel with reishi, lion’s mane or cordyceps.

Is urticaria linked to Hashimoto’s?

In a minority — but more than in the general population. In a systematic review, Hashimoto’s appeared in 5% or more of people with chronic urticaria, and a meta-analysis of 19 studies found a 5.18-fold risk of TPO antibodies. Another review describes urticaria improving with levothyroxine treatment. That is a question for a blood test at your doctor’s, not for a supplement — and anyone also taking levothyroxine will find the absorption question on the Hashimoto’s page.

Does reishi help me sleep when the itching wakes me at night?

There is not a single randomized trial of this in humans — not in urticaria and not in general. Chronic urticaria “substantially interferes with sleep”, according to a study of 673 patients, and the measured way to improve the night is controlling the disease itself. What was measured with reishi is fatigue — 28.3% versus 20.1% on placebo, in a different population.

Scientific sources (peer-reviewed)

• The international urticaria guideline: a “mast cell–driven disease” with wheals, angioedema or both; the chronic form impairs quality of life and performance; 64 delegates from 50 societies in 31 countries — Zuberbier T, et al. Allergy, 2022. View on PubMed
• GA²LEN: point prevalence 0.5–1%, peak at ages 20–40; antihistamines at the licensed dose give effective relief in fewer than 50%; updosing up to 4-fold; “sleep deprivation and psychiatric comorbidity are common” — Maurer M, et al. Allergy, 2011. View on PubMed
• The global burden: about 1% of the world’s population; more than 25% resistant to antihistamines; omalizumab and cyclosporine control two-thirds of the resistant; anxiety and depression in more than 30%; severe itch → sleep disturbance — Gonçalo M, et al. British Journal of Dermatology, 2021. View on PubMed
• ASSURE-CSU: 673 adults with disease of a year or more despite treatment; “substantially interfered with sleep”; angioedema in 66% — Maurer M, et al. Allergy, 2017. View on PubMed
• Antihistamine updosing — meta-analysis of 15 papers: 63.2% of non-responders responded; significant improvement in itch only, not in the number of wheals; weak and heterogeneous studies — Guillén-Aguinaga S, et al. British Journal of Dermatology, 2016. View on PubMed
• Omalizumab, phase 3, 323 patients: weekly itch score −9.8 at 300 mg versus −5.1 on placebo at week 12; serious events 6% versus 3%. Funded by Genentech and Novartis — Maurer M, et al. New England Journal of Medicine, 2013. View on PubMed
• Network meta-analysis of 7 trials and 410 participants: cyclosporine plus an antihistamine — the largest improvement of four immunosuppressants — Bei W, et al. International Immunopharmacology, 2023. View on PubMed
• Autoimmune comorbidity in chronic urticaria: Hashimoto’s and pernicious anemia in 5% or more, Graves’ in 2% or more, celiac disease and RA in 1% or more; more than 15% with a family history — Kolkhir P, et al. Autoimmunity Reviews, 2017. View on PubMed
• Urticaria and autoimmune thyroid disease: thyroid antibodies in 10% or more in most studies; urticaria can improve with levothyroxine treatment (strong evidence) — Kolkhir P, et al. Allergy, 2017. View on PubMed
• Meta-analysis of 19 studies, 14,351 patients versus 12,404 controls: OR 5.18 for TPO antibodies; 6.72 in the high-quality studies — Tienforti D, et al. Journal of Endocrinological Investigation, 2022. View on PubMed
• Fexofenadine in 48 healthy volunteers: AUC 1,954 with water versus 1,063 with grapefruit juice; Cmax 453 versus 253; in 41 celiac patients — absorption as in healthy people — Chretien ML, et al. BMJ Open, 2023. View on PubMed
• Interactions via intestinal OATP transporters: fexofenadine among the three most sensitive substrates; fruit juices reduce exposure by about 85% — Yu J, et al. Journal of Pharmaceutical Sciences, 2017. View on PubMed
• Rupatadine: not to be combined with cytochrome P450 inhibitors such as erythromycin or ketoconazole, because AUC and Cmax rise — Izquierdo I, et al. Drugs of Today, 2003. View on PubMed
• A reishi polysaccharide inhibited CYP2E1, CYP1A2 and CYP3A dose-dependently in rat liver microsomes — Wang X, et al. Biological & Pharmaceutical Bulletin, 2007. View on PubMed
• In human liver microsomes, on CYP3A: reishi — a “lesser effect”, IC50 above 10 micrograms per milliliter — Rodseeda C, et al. Toxicology Reports, 2022. View on PubMed
• 202 kidney-transplant recipients, cordyceps 1.0 gram ×3 a day: lower cyclosporine doses in months 2–6 and lower trough levels in months 3–6 (P<.05); doses set by blood levels, no mechanism measured; the authors: cordyceps “may allow” a lower dose — Li Y, et al. Transplantation Proceedings, 2009. View on PubMed
• Skin tests in 33 people with asthma or rhinitis: mites 36%, Ganoderma applanatum 30%, grass 27%; in asthmatics — 44% to Ganoderma, as to mites; IgE matched. A related species, not reishi — Rivera-Mariani FE, et al. Medical Mycology, 2011. View on PubMed
• Delhi: 172 respiratory-allergy patients — 28.48% reacted to reishi spore extract and 17.44% to the mushroom body; more than 80% of the positives with elevated IgE; peak of 336 spores per cubic meter — Singh AB, et al. Clinical and Experimental Allergy, 1995. View on PubMed
• Ganoderma spores in the air in Poland: a stronger season in the countryside than in the city; periods of high concentration = allergy and asthma symptoms in sensitized people — Wójcik-Kanach M, Kasprzyk I. Fungal Biology, 2025. View on PubMed
• Lion’s mane: “appears safe as a powder or capsule, but one case of anaphylaxis was reported after eating the fresh mushroom” — Muhanna M, et al. Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2024. View on PubMed
• Systematic review of lion’s mane: possible side effects include “allergic reactions”, “although generally not reported” — Menon A, et al. Frontiers in Nutrition, 2025. View on PubMed
• Erinacine A-enriched lion’s mane mycelium, 49 weeks, mild Alzheimer’s patients: three in the mycelium arm (and one on placebo) dropped out for abdominal discomfort, nausea and skin rash; researchers employed by Grape King Bio, the manufacturer — Li IC, et al. Frontiers in Aging Neuroscience, 2020. View on PubMed
• Survey of 1,374 cancer patients taking reishi: 9.1% side effects, including itching in 3%; no control group — Li X, et al. Integrative Medicine Research, 2024. View on PubMed
• Cochrane: people taking reishi for 4 months at a 1.67-fold risk of a side effect — not significant, not serious — Klupp NL, et al. Cochrane Database of Systematic Reviews, 2015. View on PubMed
• Case report (title only, no abstract): blistering hand dermatitis and hair loss in an aplastic crisis attributed to reishi — Choi MJ, et al. Annals of Hematology, 2013. View on PubMed
• Letter (title only): five cases of food allergy to wild cordyceps (“vegetable caterpillar”) with cross-reaction to silkworm pupae — Choi GS, et al. Allergy, 2010. View on PubMed
• Button-mushroom anaphylaxis in a 77-year-old woman + a review of 27 further cases: cross-sensitivity between edible mushrooms, “without a clear and consistent pattern” — Ali SB, Smith W. Journal of Allergy and Clinical Immunology: Global, 2024. View on PubMed
• A 38-year-old man allergic to mold: generalized urticaria and anaphylactic shock after button mushrooms; cross-reaction between a mushroom enzyme and mold allergens — Gabriel MF, et al. Medical Mycology Case Reports, 2015. View on PubMed
• Shiitake dermatitis in France 2014–2019: 59 cases out of 125 exposures; median onset 48 hours and duration 10 days; dose-dependent; antihistamines and steroids with no proven benefit; presumed cause — lentinan — Boels D, et al. Clinical Toxicology, 2022. View on PubMed
• Systematic review of 50 cases of shiitake dermatitis: streaks in 98%, itching in 78%, spontaneous recovery in about 12.5 days — Nguyen AH, et al. International Journal of Dermatology, 2017. View on PubMed
• “Histamine release-inhibitory triterpenes” from reishi (title only, no abstract) — Kohda H, et al. Chemical & Pharmaceutical Bulletin, 1985. View on PubMed
• An extract of reishi’s culture medium inhibited histamine release from rat mast cells; the active substance — oleic acid, 5–50 micromolar — Tasaka K, et al. Agents and Actions, 1988. View on PubMed
• Mice sensitized to mosquito saliva: reishi at 100 and 300 mg/kg reduced itching, not plasma leakage; “mast cells and H1 receptors are not the main site” — Andoh T, et al. Journal of Pharmacological Sciences, 2010. View on PubMed
• A review of mechanisms and patents — “suppression of inflammatory and allergic responses” by reishi; not a clinical study — Bhardwaj N, et al. Recent Patents on Inflammation & Allergy Drug Discovery, 2014. View on PubMed
• Purified beta-glucan from reishi in healthy adults, 84 days, randomized double-blind: rise in CD3, CD4, CD8 and NK; a significant difference in IgA and NK cytotoxicity, direction not stated — Chen SN, et al. Foods, 2023. View on PubMed
• Cochrane, reishi in cancer patients: CD3 +3.91%, CD4 +3.05%, CD8 +2.02% — Jin X, et al. Cochrane Database of Systematic Reviews, 2016. View on PubMed
• Three patients: pemphigus and dermatomyositis appeared or flared shortly after immune-stimulating supplements — echinacea and spirulina, not mushrooms — Lee AN, Werth VP. Archives of Dermatology, 2004. View on PubMed
• Reishi in neurasthenia, 132 patients, 8 weeks: fatigue −28.3% versus −20.1% on placebo — Tang W, et al. Journal of Medicinal Food, 2005. View on PubMed
• Lion’s mane 1.8 grams, 41 healthy young adults, 28 days: subjective stress p=0.051 — not significant — Docherty S, et al. Nutrients, 2023. View on PubMed
• Gulf War Illness, 29 men, pseudo-randomized crossover: high-dose reishi — higher symptom severity than placebo (p=0.012); low dose — no change; high-dose nettle — lower (p=0.048); “small sample, preliminary” — Younger J, et al. International Journal of Environmental Research and Public Health, 2021. View on PubMed

Read next

• Medicinal mushrooms and autoimmune disease — the parent page
• Reishi and seasonal allergies
• Medicinal mushrooms and the lungs — including reishi as a respiratory allergen
• Hashimoto’s and natural treatment — and what about levothyroxine
• Celiac disease and dietary supplements
• Reishi and the immune system: modulating or boosting?
• Drug interactions
• Do medicinal mushrooms have side effects?
• Who shouldn’t take reishi
• Who shouldn’t take lion’s mane
• Who shouldn’t take cordyceps
• Reishi for sleep — what was measured and what was not
• Reishi for anxiety and stress
• Lab results — beta-glucan
• How to read a certificate of analysis (COA)

This page is educational and does not constitute medical advice, diagnosis or a substitute for professional care. Medicinal mushroom extracts are dietary supplements, not drugs, and are not intended to treat urticaria, allergy or any other medical condition. Chronic urticaria requires diagnosis and follow-up by a dermatologist or allergist; swelling of the lips, tongue or throat, shortness of breath or dizziness requires urgent medical attention. Do not stop, replace or change the dose of an antihistamine, a biologic drug, cyclosporine or any other medication without your physician’s guidance. Anyone allergic to mushrooms, mold or spores should consult an allergist before any mushroom supplement. This page describes what published trials and case reports recorded — and what was not recorded; it is not a prediction of what any individual will experience, and it is not a recommendation to start, stop or combine any supplement with any medication — those decisions belong with your physician, especially if you take regular medication, are pregnant or breastfeeding, have surgery planned, or have liver or kidney disease. *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.*