The “vomit mushroom” most commonly refers to Chlorophyllum molybdites, a large white-capped mushroom also known as the green-spored parasol or false parasol. It is the most common cause of mushroom poisoning in the United States. Another species sometimes called the “vomiter” or “sickener” is Russula emetica, a bright red woodland mushroom that causes intense nausea when eaten. Both earn their nicknames honestly: they cause violent gastrointestinal distress, often within an hour or two of ingestion.
Why It’s So Often Eaten by Mistake
Chlorophyllum molybdites is a backyard mushroom. It fruits prolifically on lawns, parks, and grassy areas after summer rains, often forming fairy rings that can look impressive and inviting. The real problem is that it closely resembles several edible parasol mushrooms. Young specimens have white gills and a classic parasol shape, making them nearly indistinguishable from the edible shaggy parasol (Chlorophyllum rhacodes). Only mature specimens reveal the telltale greenish gills that give the species away.
This resemblance is what drives poisoning numbers. People who have successfully foraged parasol mushrooms before may grab a ring of these from their yard, not realizing they’ve picked the toxic lookalike. The mushroom also goes by Morgan’s Lepiota, another name you may encounter in field guides.
How to Identify Chlorophyllum Molybdites
The cap is broad, ranging from about 2 to 12 inches across. It starts out white and convex when young, then flattens and develops beige, cinnamon, or pinkish-brown scales as it matures. The flesh underneath is firm and white, sometimes staining reddish or brownish when cut.
The gills are the key. In young mushrooms they’re white to yellowish, which is exactly why misidentification happens. As the mushroom ages, the gills shift to grayish green and eventually a distinct greenish brown. The stems run 2 to 10 inches long and about half an inch to an inch thick, often getting wider toward the base. A thick ring circles the stem, starting white and darkening to orange or brown with age.
The single most reliable test is a spore print. Place the cap gill-side down on a piece of white paper for several hours. Chlorophyllum molybdites produces a dull grayish-green spore print, a color no common edible parasol shares. If you’re not confident you have a mature specimen with visible green gills, a spore print is the only way to be sure.
Russula Emetica: The Red Sickener
Russula emetica is a very different-looking mushroom but earns the same “vomiter” reputation. Its cap is uniformly bright red, cushion-shaped when young, and eventually flattening or curling upward like a shallow vase. It’s smaller than the false parasol, with caps 1 to 4 inches wide and a brittle white stalk 2 to 4 inches tall. The gills are white to off-white and closely spaced.
This mushroom grows in moss and mixed woodlands, often singly or in small groups. It has a built-in warning system that most people ignore: the flesh tastes intensely hot, spicy, and acrid. A tiny nibble (spit out, not swallowed) would immediately suggest this isn’t something you want to eat. Despite that, accidental ingestions happen, particularly among foragers who confuse it with other red-capped Russula species, some of which are edible.
What Happens After You Eat One
Symptoms from Chlorophyllum molybdites typically hit fast, usually within 30 minutes to 3 hours after eating. The poisoning is primarily gastrointestinal: severe nausea, projectile vomiting, stomach cramps, and watery diarrhea. The episodes can be violent and repeated, sometimes lasting 6 to 12 hours. In healthy adults, the illness is miserable but rarely life-threatening. Children, elderly people, and those who are already dehydrated face higher risks from fluid loss.
The toxic agent responsible appears to be a protein called molybdophyllysin, along with several steroid compounds that irritate the digestive tract. This mushroom has been documented as a gastrointestinal irritant for over a century. Unlike deadly species that contain amatoxins (the compounds that destroy the liver), Chlorophyllum molybdites does not cause organ failure. The danger is almost entirely from dehydration caused by the sustained vomiting and diarrhea.
Russula emetica causes a similar pattern of nausea, vomiting, and stomach pain, though the episodes tend to be somewhat less severe. The acrid compounds that make the raw mushroom taste so peppery are the same ones that inflame the stomach lining.
What to Do if You’ve Eaten a Suspect Mushroom
If you or someone else develops vomiting or diarrhea after eating wild mushrooms, call Poison Control at 800-222-1222 (in the United States) right away, even if the symptoms seem manageable. Time matters because the critical question isn’t just what you ate, but what you need to rule out. Mushrooms containing amatoxins can initially cause symptoms that look like simple GI upset before progressing to liver failure days later, so identifying the species is essential.
Save any leftover mushrooms, cooked or raw. If you can, also save a sample of the vomit. These can help with identification. Note when the mushrooms were eaten and when symptoms began, as the timing gap helps distinguish between different types of mushroom toxins. A short onset (under 6 hours) generally points toward GI irritants like Chlorophyllum molybdites, which is reassuring. A delayed onset of 6 hours or more raises concern for more dangerous species.
While waiting for guidance, small frequent sips of water or an electrolyte drink help counter fluid loss. Do not try to induce more vomiting beyond what the body is already doing on its own.
Recovery and What to Expect
Most people who eat Chlorophyllum molybdites recover fully within 24 to 48 hours. The worst of the vomiting and diarrhea usually passes within the first 12 hours, followed by lingering nausea and fatigue. Medical treatment, when needed, is straightforward: intravenous fluids to replace what was lost and monitoring to make sure dehydration doesn’t spiral into something worse. Severe cases can require hospital admission for aggressive fluid replacement, particularly when the person can’t keep anything down.
Russula emetica recovery follows a similar timeline, often resolving even faster since people tend to eat less of it (the terrible taste limits how much gets consumed).
Preventing Misidentification
The simplest rule: never eat a large white parasol-type mushroom from a lawn without taking a spore print first. A green or grayish-green print means you have Chlorophyllum molybdites, full stop. White or cream-colored prints are typical of the edible species. Young specimens with white gills are genuinely difficult to tell apart from edible lookalikes, even for experienced foragers. If the mushroom isn’t mature enough to show gill color or produce a reliable spore print, leave it alone.
For Russula species, the taste test is your friend. A tiny piece touched to the tongue (then spit out) will immediately reveal whether you’re holding a mild, edible Russula or the fiery emetic Russula. No edible Russula tastes like biting into a hot pepper.