If you don’t know your mushrooms well, it’s not a good idea to gather them in the wild, and for one very compelling reason : some of them that contain deadly toxins closely resemble others that are edible. Among the various different types of toxins found in mushrooms, the ones that cause the most deaths are amatoxins and orellanines.
Both Amanita phalloides (aka death cap) and Amanita virosa (aka destroying angels) contain amatoxins, a family of compounds with similar structures. A few minor differences characterise the ten identified varieties. The main culprits, which are found in significant quantities, are amanitins α, β et γ, of which a lethal dose is between 0.5 and 0.75 milligrams per kg of body weight.
Amatoxin poisoning symptoms can take anywhere from 6 to 24 hours to appear. You’ll first have stomach cramping, vomiting and diarrhea, which can resolve after a few days. The real kicker is the liver and kidney failure that can lead to death some 5 to 8 days after you’ve eaten the mushrooms. Between 10-20% of amatoxin poisoning cases are fatal, and a large proportion of survivors end up needing a liver transplant.
Cortinarius rubellus (aka deadly webcap) and Cortinarius orellanus (aka fool’s webcap) contain orellanine. At first, this makes you thirsty, with nausea, stomach cramping and partial or total retention of urine. Symptoms can take up to three weeks to appear, although usually they occur within two or three days of ingestion. The symptoms after that are the consequences of kidney damage, which can, in the most severe cases, lead to kidney failure. In these cases transplant is often the only option to treat the poisoning, since there is no known antidote to orellanine.
The most well-known poisonous mushroom is the fly amanita, with its distinctive white-splotched red cap. It contains muscarine in smaller quantities than other mushroom species – it’s estimated to make up only about 0.0003% of the mushroom’s weight. It was long thought that muscarine was the toxic element of the fly amanita, but another component, muscimol, turns out to be mostly responsible. It’s also found in another common mushroom, amanita pantherina, or panther cap. No deaths have been officially attributed to the fly amanita or panther cap, but eating them can cause dizziness, stomach cramps and hallucinations.
Unfortunately, there is no indicator for which mushroom is poisonous and which isn’t. Some of the most deadly can be very tasty, even delicious.