The False Parasol mushroom (Chlorophyllum molybdites) is the most common cause of mushroom poisoning in the United States and North America. While it does not cause liver or kidney failure, its ingestion leads to severe gastrointestinal illness. The mushroom contains a gastrointestinal irritant that causes an extremely uncomfortable and rapid reaction. Consuming this species requires immediate attention because the resulting illness can become dangerous, particularly for children, the elderly, or those with underlying health conditions, due to intense fluid loss.
Identifying the False Parasol Mushroom
Mistaken identity is the primary reason people eat the False Parasol, as it closely resembles several desirable edible species, such as the true Parasol Mushroom (Macrolepiota procera) and the Shaggy Parasol (Chlorophyllum rhacodes). The cap of a mature Chlorophyllum molybdites is large (8 to 30 centimeters in diameter), whitish, and covered with coarse, brownish scales concentrated toward the center. The mushroom often grows in lawns, pastures, and grassy areas, commonly forming large “fairy rings” or semi-circles.
The most distinctive feature for identifying this toxic mushroom is its spore color. While the gills start out white in young specimens, they gradually turn a grayish-green to brownish-green as the mushroom matures. A spore print, created by placing the cap on paper, will reveal a dull grayish-green color, a unique trait among large, white-gilled mushrooms.
Another characteristic is the ring, or annulus, on the stem, which is thick, persistent, and movable. Unlike the true Parasol Mushroom, the stalk of the False Parasol typically lacks the distinctive snakeskin-like pattern. The combination of a large, scaly cap, a stem ring, and the greenish tint of the mature gills serves as a strong warning sign.
The Gastrointestinal Effects and Symptom Timeline
The severe physical reaction is caused by a gastrointestinal irritant, likely a heat-labile protein called molybdophyllysin, present throughout the mushroom. Symptoms are not delayed, with onset occurring rapidly, generally within one to three hours after ingestion. This quick reaction time is a characteristic feature of this type of mushroom poisoning.
The initial experience involves severe nausea, quickly followed by intense and sometimes projectile vomiting. This is accompanied by significant abdominal pain and profuse, watery diarrhea. In severe cases, the diarrhea may even become bloody.
The acute phase of the illness, marked by intense vomiting and diarrhea, typically lasts for 12 to 24 hours. Other reported symptoms include chills, cold sweats, and dizziness. This profound gastrointestinal distress is the body’s attempt to forcefully expel the irritant.
Severity of Illness and Necessary Medical Action
While ingesting Chlorophyllum molybdites is rarely fatal for a healthy adult, the illness is extremely uncomfortable and carries a significant risk of severe dehydration and electrolyte imbalance. The rapid loss of fluids through vomiting and diarrhea can lead to dangerously low blood pressure, known as hypovolemic shock, especially in vulnerable populations. Children, who have less body mass, are at a higher risk of complications from this rapid dehydration.
If any part of a False Parasol mushroom is consumed, contact Poison Control or seek urgent medical attention immediately. The medical approach focuses on supportive care, which involves managing the symptoms and correcting fluid and electrolyte losses. Intravenous fluids are often administered in a hospital setting to rehydrate the patient and restore the body’s balance.
Patients should bring any remaining parts of the mushroom, or a sample of the vomit, to the hospital for positive identification. This helps medical professionals confirm the species and rule out other toxic mushrooms that may have a delayed onset of symptoms. Recovery is generally complete within 48 to 72 hours, with symptoms fully resolving, though weakness or fatigue may linger.