The Lethal webcaps, two species in the genus Cortinarius, are two of the world’s most poisonous mushrooms. The species are the Deadly webcap (Cortinarius rubellus, formerly also known as C. speciosissimus) and the Fool’s webcap, C. orellanus. The mushrooms’ characteristics are quite common, making them difficult to identify, which often leads to fatal poisonings. Young examples of the species often have a veil between the cap of the mushroom and the stem. This veil looks like a cobweb, hence the name. The veil however partially or completely disappears in older specimens.
Deadly webcap (Cortinarius rubellus)
Spore color: Rusty brown to orange
Cap: 3–7 cm rusty brown to orange. Often has a steeper and darker colored elevation at the top of the cap, but this varies greatly from specimen to specimen
Gills: Wide gaps between the gills which can be, but are not necessarily, connected to the stem
Location: Rare, but common in temperate parts of northern Europe. Has been encountered as far north as Finnish Lapland.
Habitat: Pine woods with acidic soil
Other details: Young specimens contain a pale web between the cap and the stem. Sometimes parts of this web can be seen as a yellow ring on the stem or at the edge of the cap. The fruiting body of the mushroom blossoms from mid-summer to late autumn.
Fool’s webcap (Cortinarius orellanus)
- Spore color: Rusty brown to orange
- Cap: 3–8.5 cm, concave
- Gills: Similar to those of the deadly webcap
- Location: Common throughout Europe, rare in the northern parts of Europe. Has been observed as far north as southern Norway
- Habitat: In forests, around trees where the soil is alkaline or acidic
- Other details: Young specimens of the Fool’s webcap also contain a web between the cap and the stem that partially or completely disappears as the specimen ages.
Both of these mushrooms can be confused with each other and many incidents of mushroom poisoning have occurred where inexperienced mushroom hunters have confused these mushrooms with edible mushrooms, such as the chanterelle, or hallucinogenic mushrooms. One should be especially cautious when picking mushrooms like the cleaned funnel chanterelles as these mushrooms share the same habitat as the deadly webcap and the fool’s webcap. In many incidents where this mushroom has been ingested, death has occurred.
In Poland during the 1950s there was a small epidemic where over 100 people became ill. What caused the illness remained a mystery until 1952 when Polish physician Dr. Stanislaw Grzymala discovered that everyone suffering from the illness, which by then had claimed several lives, had eaten the mushroom Cortinarius orellanus.
These mushrooms are sometimes stated to be so poisonous that one could be poisoned even after tasting and spitting out a small piece. The LD50 of orellanin in mice is 12–20 mg per kg body weight. From cases of orellanine-related mushroom poisoning in humans it seems that the lethal dose for humans is considerably lower.
The Deadly webcap and the Fool’s webcap both contain the toxin orellanin and orellin, orellinin and Cortinarin A,B,C . A characteristic of orellanin poisoning is the long latency; the first symptoms usually don’t appear until 2–3 days after ingestion and can in some cases take as long as 3 weeks. The first symptoms of orellanin poisoning are similar to the common flu (nausea, vomiting, stomach pains, headaches, etc.). These symptoms are followed by early stages of renal failure (immense thirst, frequent urination, pain on and around the kidneys), and eventually decreased or nonexistent urine output and other symptoms of renal failure occur. If left untreated death will follow. There is no known antidote against orellanin poisoning, but early hospitalization and treatment can sometimes prevent serious injuries and usually prevent death. If you suspect orellanin poisoning, acting on it quickly can save your life.
Several more mushrooms in the Cortinarius genus are suspected to contain orellanin or other deadly toxins. Among them are Cortinarius callisteus and Cortinarius limonius.
The Deadly Webcap is reputedly the poisonous mushroom collected in mistake for chanterelles by Nicholas Evans, famous author of (among other works) ‘The Horse Whisperer’ – subsequently made into a highly acclaimed film by Robert Redford -and ‘The Loop.’ Mr Evans and three members of his family suffered serious kidney damage and were hospitalised in Scotland.
The initial symptoms of orellanine poisoning are usually delayed by two or three days, after which flu-like symptoms, headache and vomiting occur. Renal (kidney) failure follows and if not treated can result in death.
Dialysis and other kidney and liver treatments, if received quickly enough, can usually save the lives of people who eat these dangerous Cortinarius mushrooms – as it did in the case of Nicholas Evans – but full recovery is a very long and unpleasant process.
Several other fungi from the Cortinarius genus, including Cortinarius orellanus, are now known to contain the same toxin, and so most experts advise that no webcap fungi should ever be eaten.
Poisonous mushrooms contain a variety of different toxins that can differ markedly in toxicity. Symptoms of mushroom poisoning may vary from gastric upset to life-threatening organ failure resulting in death. Serious symptoms do not always occur immediately after eating; often not until the toxin attacks the kidney or liver, sometimes days or weeks later.
The most common consequence of mushroom poisoning is simply gastrointestinal upset. Most “poisonous” mushrooms contain gastrointestinal irritants which cause vomiting and diarrhea (sometimes requiring hospitalization), but usually no long-term damage. However, there are a number of recognized mushroom toxins with specific, and sometimes deadly, effects:
Alpha-amanitin (deadly: causes liver damage 1–3 days after ingestion) – principal toxin in genus Amanita.
Phallotoxin (causes gastrointestinal upset) – also found in poisonous Amanitas
Orellanine (deadly: causes kidney failure within 3 weeks after ingestion) – principal toxin in genus Cortinarius.
Muscarine (sometimes deadly: can cause respiratory failure) – found in genus Omphalotus.
Gyromitrin (deadly: causes neurotoxicity, gastrointestinal upset, and destruction of blood cells) – principal toxin in genus Gyromitra.
Coprine (causes illness when consumed with alcohol) – principal toxin in genus Coprinus.
Ibotenic acid (causes neurotoxicity) and muscimol (hallucinogenic) – principal toxins in A. muscaria, A. pantherina, and A. gemmata.
Psilocybin and psilocin (hallucinogenic, ‘magic’, ‘psychoactive’) – principal ‘toxin’ in genus Psilocybe.
Arabitol (causes gastrointestinal irritation in some people).
Bolesatine a toxin found in Boletus satanas
Ergotamine (deadly: affects the vascular system and can lead to loss of limbs and death): An alkaloid found in genus Claviceps.
Symptoms of mushroom poisoning vary depending on the toxins involved.
Alpha-amanitin: For 6–12 hours, there are no symptoms. This is followed by a period of gastrointestinal upset (vomiting and profuse, watery diarrhea). This stage is caused primarily by the phallotoxins and typically lasts 24 hours. At the end of this second stage is when severe liver damage begins. The damage may continue for another 2–3 days. Kidney damage can also occur. Some patients will require a liver transplant. Amatoxins are found in some mushrooms in the genus Amanita, but are also found in some species of Galerina and Lepiota. Overall, mortality is between 10 and 15 percent. Recently, Silybum marianum or blessed milk thistle has been shown to protect the liver from amanita toxins and promote regrowth of damaged cells, including a study in which 60 patients exposed to death cap poison were given 20 mg/kg of milk thistle seeds per day within 48 hours of consuming the deadly mushrooms. None of the patients died.
Orellanine: This toxin causes no symptoms for 3–20 days after ingestion. Typically around day 11, the process of kidney failure begins, and is usually symptomatic by day 20. These symptoms can include pain in the area of the kidneys, thirst, vomiting, headache, and fatigue. A few species in the very large genus Cortinarius contain this toxin. People who have eaten mushrooms containing orellanine may experience early symptoms as well, because the mushrooms often contain other toxins in addition to orellanine. A related toxin that causes similar symptoms but within 3–6 days has been isolated from Amanita smithiana and some other related toxic Amanitas.
Muscarine: Muscarine stimulates the muscarinic receptors of the nerves and muscles. Symptoms include sweating, salivation, tears, blurred vision, palpitations, and, in high doses, respiratory failure. Muscarine is found in mushrooms of the genus Omphalotus, notably the Jack o’ Lantern mushrooms. It is also found in A. muscaria, although it is now known that the main effect of this mushroom is caused by ibotenic acid. Muscarine can also be found in some Inocybe species and Clitocybe species, particularly Clitocybe dealbata, and some red-pored Boletes.
Gyromitrin: Stomach acids convert gyromitrin to monomethylhydrazine (MMH), a compound employed in rocket fuel. It affects multiple body systems. It blocks the important neurotransmitter GABA, leading to stupor, delirium, muscle cramps, loss of coordination, tremors, and/or seizures. It causes severe gastrointestinal irritation, leading to vomiting and diarrhea. In some cases, liver failure has been reported. It can also cause red blood cells to break down, leading to jaundice, kidney failure, and signs of anemia. It is found in mushrooms of the genus Gyromitra. A gyromitrin-like compound has also been identified in mushrooms of the genus Verpa.
Coprine: Coprine is metabolized to a chemical that resembles disulfiram. It inhibits aldehyde dehydrogenase (ALDH), which generally causes no harm, unless the person has alcohol in their bloodstream while ALDH is inhibited. This can happen if alcohol is ingested shortly before or up to a few days after eating the mushrooms. In that case the alcohol cannot be completely metabolized, and the person will experience flushed skin, vomiting, headache, dizziness, weakness, apprehension, confusion, palpitations, and sometimes trouble breathing. Coprine is found mainly in mushrooms of the genus Coprinus, although similar effects have been noted after ingestion of Clitocybe clavipes.
Ibotenic acid: This organic acid is metabolized to muscimol. The effects of muscimol vary, but nausea and vomiting are common. Confusion, euphoria, or sleepiness are possible. Loss of muscular coordination, sweating, and chills are likely. Some people experience visual distortions, a feeling of strength, or delusions. Symptoms normally appear after 30 minutes to 2 hours and last for several hours. A. muscaria, the “Alice in Wonderland” mushroom, is known for the toxic/hallucinogenic properties caused by muscimol, but A. pantherina and A. gemmata also contain the same compound. While normally self-limiting, fatalities have been associated with A. pantherina, and consumption of a large number of any of these mushrooms is likely to be dangerous.
Psilocybin: This compound is converted into psilocin when ingested. Symptoms begin shortly after ingestion. The effects can include euphoria, visual and religious hallucinations, and heightened perception. However, some persons experience fear, agitation, confusion, and schizophrenia-like symptoms. All symptoms generally pass after several hours. Some (though not all) members of the genus Psilocybe contain psilocybin, as do some Panaeolus, Copelandia, Conocybe, Gymnopilus, and others. Some of these mushrooms also contain baeocystin, which has effects similar to psilocin.
Arabitol: A sugar alcohol, similar to mannitol, which causes no harm in most people but causes gastrointestinal irritation in some. It is found in small amounts in oyster mushrooms, and considerable amounts in Suillus species and Hygrophoropsis aurantiaca (the “false chanterelle”).
Some mushrooms contain less toxic compounds and, therefore, are not severely poisonous. Poisonings by these mushrooms may respond well to treatment. However, certain types of mushrooms, such as the Amanitas, contain very potent toxins and are very poisonous; so even if symptoms are treated promptly mortality is high. With some toxins, death can occur in a week or a few days. Although a liver or kidney transplant may save some patients with complete organ failure, in many cases there are no organs available. Patients who are hospitalized and given aggressive support therapy almost immediately after ingestion of amanitin-containing mushrooms have a mortality rate of only 10%, whereas those admitted 60 or more hours after ingestion have a 50–90% mortality rate.
Siddhartha Gautama (known as The Buddha), by some accounts, may have died of mushroom poisoning around ~479 BCE, though this claim has not been universally accepted.
Roman Emperor Claudius is said to have been murdered by being fed the death cap mushroom. However this story first appeared some two centuries after the events, and it is even debatable whether Claudius was murdered at all. Pope Clement VII is also rumored to have been murdered this way. However it is similarly debated whether he died from any kind of poisoning at all.
Holy Roman Emperor Charles VI and Tsaritsa Natalia Naryshkina are believed to have died from eating the death cap mushroom. According to a popular legend, the composer Johann Schobert died in Paris, along with his wife, one of his children, maidservant and four acquaintances after insisting that certain poisonous mushrooms were edible.
The best-selling author Nicholas Evans (The Horse Whisperer) was poisoned after eating Cortinarius speciosissimus. The parents of the physicist Daniel Gabriel Fahrenheit, who created the Fahrenheit temperature scale, died in Danzig on 14 August 1701 from accidentally eating poisonous mushrooms.