A poisonous mushroom is any mushroom or toadstool that causes a negative reaction when eaten. Symptoms can vary from mild stomach upset to lethal liver or kidney failure.
There are about 5,000 types of mushrooms found in the United States and of these, about one hundred are responsible for most mushroom poisonings. Less than a dozen species are considered deadly, however death from other species, even so-called “safe” mushrooms, has occurred in very young children or in ill adults.
Q: Is it possible to easily tell the difference between a poisonous and non-poisonous mushroom?
A: No. There are no non-scientific tests or rules that can accurately determine the safety or toxicity of a mushroom. Using the following “rules” could prove to be a deadly mistake!
People commonly believe that mushrooms are only poisonous if:
- The mushroom stains when bruised
- The mushroom secretes a milky sap
- The mushroom turns garlic blue or black when cooked together
- The mushroom turns a silver coin black when rubbed against it
- The mushroom tarnishes a silver spoon when cooked with it
- The mushroom has scales, warts or other types of rough surfaces
And common misconceptions for determining whether a mushroom is safe:
- The mushroom grows on wood
- Slugs or other insects eat the mushroom
- Squirrels, rabbits, or other wildlife eat the mushroom
- The mushroom is dried, boiled, salted or pickled in vinegar
- The mushroom does not have a ring or skirt on the stalk
- The mushroom is pure white in color
A Few Facts
Neither list above is complete—you cannot reliably determine if a mushroom is poisonous. Here are a few facts about poisonous mushrooms:
- Some people can eat mushrooms with no problems, while other people eating the same mushroom will experience severe vomiting and diarrhea.
- Some people can have allergic reactions to eating “safe” mushrooms.
- Some mushrooms are only poisonous if eaten in large quantities.
- Some mushrooms are poisonous when raw but become harmless when parboiled and thoroughly cooked.
- Some mushrooms are poisonous regardless of how they are cooked or prepared.
- Some mushrooms are poisonous only if eaten with alcoholic beverages.
- Some mushrooms are classified as poisonous because they are hallucinogenic.
- Some mushrooms that are edible when fresh and young become poisonous when they are old, hit by frost, or if they decay.
- Some mushrooms, for unknown reasons, are poisonous in one part of the country and are not poisonous in another.
- Some mushrooms that are poisonous to animals do not cause major problems in humans.
- Most mushrooms are more dangerous to young children, the aged, and the very ill.
What To Do
Consider all mushrooms found outside unsafe. Mistakes are common and symptoms could be severe. Be safe and only select mushrooms from the varieties in your grocery store.
Do not wait for symptoms to appear. Call 1-800-222-1222 right away.
Many of the most toxic mushrooms have delayed symptoms, so just because a person or animal appears fine does not mean that everything is OK. Symptoms may not develop until several days later.
There are NO antidotes for mushroom poisoning!
Mushrooms from the Grocery Store
All mushrooms that are not purchased from a grocery store are considered potentially dangerous. Call the Poison Center at 1-800-222-1222 as soon as you even suspect a mushroom ingestion.
Mushrooms from the Yard
Spring and fall seasons with cool, damp evenings encourage mushroom growth. Check your yard for mushrooms before letting young children and pets out to play—remove all mushrooms. Teach children not to taste or even touch any outdoor mushrooms.
Do not add mushrooms from the wild to your dishes unless you are absolutely positive that the mushroom has been accurately identified and is safe.
Want to print a copy of this information? We have a Mushrooms Fact Sheet in pdf.