How To Tell If A Mushroom Is Poisonous?
About 14,000 different mushroom species have been catalogued worldwide. Some of them are edible while some are not.
Many inedible, poisonous mushrooms look similar to the edible ones and because of this, thousands of people suffer mushroom poisoning each year.
According to the Western Pennsylvania Mushroom Club, there were 83,140 possible cases from 2001 to 2012 of which 45 people died. In France, a total of 1,675 cases of mushroom poisoning were reported in 1998.
Although it seems the likelihood of dying is low, the figures from those surveys may have been due to the small ingested portions or fast actions taken to treat the victims.
But make no mistake. Up to 60 percent of cases involving the Amanita genus and a great number of other species can kill an adult easily.
Symptoms of poisoning from less toxic mushrooms can range from discomfort to serious health threats. That is why it is important to know which wild mushrooms to avoid, whether they are picked or purchased.
The pictures in a mushroom guide may not be enough as the appearance of a mushroom can change according to its stage of life and environmental conditions.
Identifying a poisonous mushroom can be very tricky but there are some general characteristics to look out for. But first, you’ll need to know the terms used to describe parts of a mushroom, which is covered in the first section of this article.
Parts of a mushroom
Cap
This is the top part of the mushroom. It can have many shapes – parasol, cup, conical, round or concave. Depending on the species and age of the mushroom, its surface can be mottled, smooth or covered with small nibs. It may or may not have skin that is easy to peel off.
Stem
Some species of mushrooms or fungi have stems, some don’t. The stems can be long and slender, or short and fat. Some stems are hollow, some are dense. Often, fungi growing on decayed wood don’t have stems. Mushrooms that look like balls also don’t have stems.
Gills
The gills are under the cap. It is the spore-producing part of the mushroom. Gills can be ribbed or consist of a large number of small holes. Some species have protuberances called teeth while others have veins.
Ring or Annulus
The ring looks like a kind of skirt around part of the stem. It can be very short and broken or more pronounced, like a long skirt.
Volva
This is a bulging section at the base of the stem, often hidden underground. Mushroom stems without volvas will be straight from top to end.
Characteristics of a poisonous mushroom
The features of toxic fungi mentioned in this article are not fail-safe, as many edible species also have some of these characteristics. The guidelines listed here are merely indications of poison in mushrooms.
- White gills
- Ring around the stem
- Presence of a volva which might be hidden by soil
- Red color on the cap, stem or pores
- Found growing on certain woods, such as yew, cedar, eucalyptus, conifer
- Cap changes colour when cut or pressed
- Parasol or umbrella-shaped caps
- Small and brown mushrooms
- Spore print test results (remove the stem and press the gills on a piece of paper or clear glass for a few to several hours) – white is a sign of the deadly Amanita species
- The flesh of mushroom stains blue when it is cut
- Gills release a milky substance when they are damaged or touched
- The stem and/or cap is brittle
- Bumps or scales on the cap
- Old, decayed or bitten by something (even edible mushrooms in these states can make you sick)
Some toxic mushroom species have 1 of the 13 characteristics above while some species have a combination of a few. The best way to be 100 percent sure of whether a fungi is toxic or not, is by asking a mycologist or fungi expert.
If you see only 1 of the characteristics mentioned above, it is best to steer clear of these fungi; rather than chance the Russian roulette of eating a toxic one.
Signs of mushroom poisoning
To be very clear, toxins in a poisonous mushroom usually cannot be removed. No cooking, canning or freezing can magic the toxins away. In fact, cooking some toxic fungi will release the toxins into the air.
Mushroom toxins can be divided into 4 broad categories:
- Protoplasmic toxin – destroys body cells and eventually cause organ failure
- Neurotoxin – leads to various neurological symptoms like spastic colon and depression, hallucination, excessive sweating, coma, convulsion
- Gastrointestinal irritant – causes vomiting, nausea, diarrhea and abdominal cramp
- Disulfiram-like toxin – produced when toxic fungi is eaten with alcohol (shows up within 3 days after consumption)
Symptoms of poisoning do not always show up immediately. Some are only evident 48 hours after ingesting the mushroom.
The severity of symptoms varies from case to case with the worst being death within only 3 to 6 days after ingestion. That is why it is critical to seek immediate medical attention when any symptoms arise.
Symptoms of mushroom poisoning can be further classified into categories based on the types of toxins. The categories of symptoms are called syndromes and some of them are listed in the table below:
| Syndromes | Initial symptoms |
| Gastrointestinal irritants | Nausea, vomiting, cramps and diarrhea within 20 minutes to 4 hours after ingestion |
| Muscarine | Sweating, salivation, tearing, slow heart rate, low blood pressure, blurry vision, irregular pulse and difficulty breathing |
| Isoxazole derivatives | Nausea and vomiting, feeling drunk, drowsiness, apparent coma (muscimol), hyperactivity, myotonic jerks, convulsions, delusions, and hallucinations (ibotenic acid) |
| Amatoxins | Severe vomiting, bloody diarrhea, and abdominal cramps with relapse 3 to 5 days after the ingestion, kidney and liver failure, internal bleeding, death |
| Gyromitrin | Headache, gastrointestinal discomfort |
| Orellanine | Nausea, vomiting, lethargy, anorexia, frequent urination, burning thirst, headache, feeling of coldness and shivering (three days to three weeks after ingestion) |
| Psilocybin & other indole derivatives | Heightened color perception, emotional effects ranging from ecstasy to anxiety, and sometimes hallucinations or delusions |
| Coprine & other alcohol-induced syndromes | Increased heart rate, palpitations, nausea, tingling, flushing and headache |
| Miscellaneous & Unknown: Rhabdomyolysis syndrome | Cardiac and respiratory complications, leading to death |
| Erythromelalgia syndrome | Painful flushing of the hands, feet and nose (maldistribution of blood flow) |
| Rash | Rash similar to poison ivy in sensitive individuals |
| Immunohemolytic anemia | Gastrointestinal symptoms within 3 hours of ingestion, acute hemolytic anemia with hemoglobinuria and renal failure |
| Bolesatine | Protein synthesis inhibited |
| Others | Muscle breakdown, kidney damage, pneumonitis (from inhaling spores), etc. |
This list is by no means complete. If any of the above symptoms are present or a wild mushroom has been ingested, you should always contact a mushroom poisoning emergency center or bring the victim to an emergency room immediately.
Top toxic mushrooms to watch out for
There are 3 groups of fungi which are the most dangerous. They are the amanitas, the false morels and a catch-all category known as little brown mushrooms (LBM).
Amanita mushrooms account for 90 percent of mushroom-related deaths in the United States. Certain species in the false morel and LBM groups have also caused death.
Can you be poisoned by touching a mushroom?
There is a possibility. That is why it is always advisable to wear a waterproof glove when handling unfamiliar wild mushrooms.
The toxins in mushrooms can only harm you if you ingest them. However, if any toxic pores or secretions (either from the gills or cracks in the flesh) gain contact with your mouth, eyes or nose, there is a risk of poisoning.
What happens if you breathe in mushroom spores?
The spores of certain fungi can cause you to get very sick. There was a well-documented incident in 1994 where 8 teenagers in Wisconsin, USA, were admitted for respiratory illnesses after they inhaled and chewed puffball mushrooms.
Their first symptoms were nausea and vomiting within 12 hours of exposure. Within 7 days they developed cough, shortness of breath, fever, myalgia and fatigue. All of the teenagers suffered from inflamed lungs and needed almost a month to recover.
Conclusion
It is not easy to tell the difference between a poisonous mushroom from an edible one, especially in the wild. The safest mushrooms to consume are still the store-bought ones.
Many people have made the mistake of thinking it is okay to pick wild mushrooms just by following the pictures of a book on mushrooms.
The truth is, only an expert can do so in a 100 percent safe way, as there are many look-alikes between edible and poisonous species.
Too many cases of mushroom poisoning are reported each year caused by misidentification and lack of knowledge. The lucky victims get away with mild symptoms while the unfortunate ones end up needing a liver transplant, or lose their lives.
In fact, mushrooms are tricky in the sense that even some edible species contain poisonous compounds. Some people are not affected by these but some can suffer adverse reactions.
