Death cap mushrooms, also known as Amanita phalloides, are a deadly poisonous basidiomycete fungus. They are one of many in the genus Amanita and are widely distributed across Europe, but have been introduced to other parts of the world since the late twentieth century. Death cap mushrooms are ectomycorrhizal fungi and form a symbiotic relationship with the roots of trees. They are typically found growing near broadleaf trees such as oaks, birches, and elms. The appearance of the death cap mushroom is somewhat similar to other species of mushroom that are nonpoisonous, which contributes to the number of unintentional poisonings.

The toxins of the death cap mushrooms primarily target the liver, but other organs, such as the kidneys, are also affected. The symptoms of death cap mushroom poisoning include low blood pressure, nausea, and vomiting, which begins 8 to 12 hours after ingestion. After up to 24 hours have passed, the symptoms seem to disappear, and the person might feel fine for up to 72 hours. Symptoms of liver and kidney damage start 3 to 6 days after the mushrooms were eaten. On average, one person dies a year in North America from death cap ingestion. Death cap mushrooms are responsible for about 90% of mushroom-related deaths globally.

It is important to note that death cap mushrooms cannot be destroyed by cooking or drying. If you suspect you have eaten a death cap mushroom, you should immediately go to an emergency room. Early treatment is important. If the patient is at an advanced stage of poisoning, extreme measures like a liver transplant may be necessary. Safe plants that look like death cap mushrooms include Asian straw mushrooms and other edible species of Amanita. Death cap mushrooms can be distinguished from similar species by the large, bulbous cup at the base of the stalk. When picking mushrooms, it is important to pull the full mushroom out of the ground to confirm that you have picked an edible relative and not the poisonous death cap.