eMedicine Specialties > Emergency Medicine > Toxicology

Toxicity, Mushroom - Muscarine

Author: Peter A Chyka, PharmD, FAACT, DABAT, Professor and Executive Associate Dean, College of Pharmacy, University of Tennessee Health Science Center
Coauthor(s): William Banner Jr, MD, PhD,, Medical Director, Oklahoma Poison Control Center; Clinical Professor of Pharmacy, Oklahoma University College of Pharmacy-Tulsa; Adjunct Clinical Professor of Pediatrics, Oklahoma State University College of Osteopathic Medicine
Contributor Information and Disclosures

Updated: Oct 14, 2009

Introduction

Background

Although many mushrooms may contain cholinergic toxins like muscarine in small amounts, it is the mushrooms of the Inocybe and Clitocybe genera that contain sufficient amounts to produce a muscarinic cholinergic poisoning. In particular, Amanita muscaria is named for trace amounts of muscarine present but it does not cause clinical cholinergic toxicity.

Muscarine was first extracted from Amanita muscaria in 1869, but this mushroom does not contain significant amounts of muscarine to cause toxicity . Ibotenic acid and muscimol are the major toxins in this mushroom and cause ethanol-like intoxication and jerking movements.

Mushroom poisoning in children is an infrequent but perennial problem for parents and clinicians. Parental anxiety is generally high because of fears of unknown or untoward effects. Clinicians are challenged to identify such poisonings, to discern whether poisoning has taken place, to order appropriate diagnostic studies, and to prescribe reasonable therapy. The varied nature of mushroom toxicities, their ubiquitous distribution, and the relative infrequency of the ingestions make the task difficult.

Several general types of mushrooms can cause poisoning:^3,4,5

• Cyclopeptides (eg, Amanita phalloides) - Hepatotoxic
• Orellanine and orelline (Cortinarius mushrooms) - Nephrotoxic
• Ibotenic acid and muscimol (A muscaria, A pantherina), also termed isoxazoles - Intoxication and jerking movements
• Gyromitrin or monomethylhydrazine (Gyromitra mushroom) - Hemolytic
• Muscarine (Inocybe and Clitocybe mushrooms) - Cholinergic
• Coprine (Coprinus atramentarius, inky cap) - Disulfiramlike reaction
• Psilocybin (Psilocybe and Paneolus mushrooms, magic mushrooms) - Hallucinogenic
• GI irritants
• Allenic norleucine (Amanita smithiana) - Nephrotoxic
• Myotoxic (Tricholoma equestre) - Rhabdomyolysis

A classification of 14 syndromic categories of mushroom poisoning has been also proposed, but this classification system has yet to be widely adopted.^6,7

Pathophysiology

Muscarine stimulates M1 and M2 types of postganglionic cholinergic receptors (muscarinic receptors) in the autonomic nervous system. This action results in parasympathetic stimulation similar to that caused by the release of endogenous acetylcholine at postganglionic receptors of smooth muscle and the exocrine glands, such as sweat, bronchial, lacrimal, salivary, and gastrointestinal. The action on muscarinic receptors produces a cholinergic syndrome that is characterized by sweating, bronchorrhea with shortness of breath, salivation, lacrimation, diarrhea, miosis, abdominal cramps, and bradycardia. There is negligible activity on nicotinic receptors; hence, muscle weakness, fasciculations, and paralysis are not present. Because muscarine is a quaternary amine, it does not readily cross the blood-brain barrier and does not directly cause CNS effects. Muscarine is not metabolized by cholinesterase and has a longer biologic half-life than acetylcholine.

Frequency

United States

In 2007, 7351 mushroom ingestions were reported to the National Poison Data System of the American Association of Poison Control Centers (AAPCC).⁸ Of these cases, 86% of cases involved mushrooms of unknown type. Mushrooms containing muscarine accounted for 27 cases, with 4 (15%) involving children younger than 6 years. About 15% of all cases involving muscarine were intentional ingestions and 70% were treated at a healthcare facility. No deaths from muscarine-containing mushrooms were reported in 25 years of data collection by AAPCC.

International

The incidence of all types of toxic mushroom poisonings, including those from the muscarine group, appears to be increasing in Europe and Asia. Estimates of the actual incidence are not available.^6,7

Mortality/Morbidity

Fatalities from muscarine mushroom poisoning are very rare, and symptoms typically are mild to moderate in severity and self-limiting.

• From 1999-2007, 28 deaths due to mushrooms were reported to US poison control centers through the AAPCC, but none were attributed to muscarine mushroom poisoning.
• For the 27 exposures to muscarine-containing mushrooms reported by US poison control centers through the AAPCC, 63% of cases had no or minor effects, 7% had moderate effects, 4% suffered severe effects, and the outcome was unknown in 26% during 2007.⁸
• Most toxic effects of mushrooms containing muscarine are temporary and self-limiting, lasting 6-24 hours.^1,2
• In Australia, a 53-year-old woman ate 2 large mushrooms (leftovers later identified as a Bolete mushroom, Rubinoboletus sensu lato pro tempe) and came to a hospital with a 2-hour history of headache, chest and abdominal pain, vomiting, and profuse sweating. At 3 hours, she also developed diarrhea and her condition deteriorated rapidly with hypotension, bradycardia, coma, and respiratory distress. At 7 hours, she remained in shock and did not respond to resuscitative measures. During the first hour of hemodialysis, she developed asystole and died 10 hours after ingestion. The patient's partner had eaten some of the mushrooms, but promptly vomited and did not exhibit any toxic effects.⁹ Whether this mushroom grows in North America is unknown.

Descriptions of cases reported to the North American Mycological Association, toxicology section illustrate the typical course of many mushroom poisonings; however, these cases were not necessarily observed by health care professionals.¹⁰

Age

Adults are frequently involved as foragers for edible mushrooms. Because of errors in identification, they may ingest toxin-containing look-alike mushrooms. Adults and adolescents may also be inadvertently poisoned when they intentionally consume mushrooms, picked from the ground or purchased dried, to achieve intoxication. Young children may be poisoned by mushrooms when they unintentionally eat mushrooms found outside, typically in yards or outdoor play areas.

Clinical

History

Ask the patient about how many mushrooms were consumed, how they were prepared, and when the mushrooms were eaten. The concentration of active substances is low in any one mushroom. The effects of mushrooms vary greatly, and cooking may not alter toxicity. Typically, the amount consumed at a meal or a single whole mushroom is sufficient to cause symptoms.¹

• Obtain a history of the exposure that includes the following:
  • Quantity of mushrooms ingested
  • Preparation of the mushroom (eg, raw, cooked)
  • Source of the mushroom (eg, outdoors, the Internet)
  • Time of the ingestion
  • Symptoms and time of onset after ingestion
  • Prehospital treatment including home remedies
  • Medications regularly taken and any coingestants
  • Past medical history with a focus on arrhythmias, asthma, prostatic hypertrophy, and gastric outlet obstruction
• The timing of symptom onset is a crucial element of the history in differentiating life-threatening or severe mushroom poisonings from those that are less serious and typically have an onset of symptoms well within 5 hours of ingestion such as the muscarine-containing mushrooms.^6,7,3,4,5
  • Mushrooms from the cyclopeptide (Amanita phalloides) or orellanine (Cortinarius mushrooms) groups, which can produce hepatic or renal failure, respectively, typically produce symptoms 6-24 hours after ingestion.
  • Amanita smithiana (allenic norleucine group) found in the Northwestern states can also be nephrotoxic, but it has an onset of gastrointestinal distress within 1-12 hours.¹¹ These mushrooms are often confused with edible pine mushrooms.
  • For mushroom ingestions in the Pacific Northwest region of the United States, patients who have early-onset symptoms and remain symptomatic should be fully evaluated in a hospital until the mushroom identity is confirmed to be nontoxic or the patient’s condition improves.⁵
• Identification of the actual mushroom consumed is important but is typically impossible because the mushroom in question has already been digested.
  • Clitocybe mushrooms are found as single specimens on lawns in the summer and fall. The mushrooms are whitish tan-to-gray and have 15- to 33-mm caps. Their stalks are hairless and are 1- to 5-cm long. Their gills are decurrent (running down the stalk), and the spores are white.
  • Inocybe mushrooms are typically found in or under hardwoods and conifers in the summer and fall. The mushrooms are small and brown and have conical caps as large as 6 cm in diameter. Stalks are 2-10 cm and have fine, brown-to-white hairs. The gills are notched, and the spores are brown.
  • Different types of mushrooms can be found in the same location, and a single sample can lead to false identification of the mushroom that was ingested. Consider all possible mushrooms in the immediate vicinity of where the ingestion occurred.
  • When no specimen is brought in by a patient with a suspected mushroom ingestion, sending an experienced forager to the site to collect any mushrooms growing in the area might be helpful.
  • When mushrooms are obtained for identification, the entire mushroom should be dug up to preserve the architecture of the bulb, stem, and cap. Place individual mushrooms in a dry, paper bag, not a plastic or cloth bag. Transporting the mushrooms in a careful, dry manner minimizes destruction of the natural architecture of the mushrooms, discoloration of the cap or gills, and premature release of the spores. Do not refrigerate or crush the mushrooms.
  • Collecting the patient's gastric contents by means of gastric lavage or after emesis might yield identifiable spores.
  • Remote viewing of the mushroom by digital photography and Internet transmission may aid the identification of unknown mushrooms by mycologists.¹²

Physical

Signs and symptoms related to the ingestion of a muscarine-containing mushroom typically appear after 0.5-2 hours and may last for 6-24 hours. Muscarinic effects, such as sweating, salivation, lacrimation, urination, defecation, abdominal cramps, miosis, emesis, bronchorrhea with shortness of breath, and bradycardia are seen. Profuse sweating and facial flushing are prominent features and should raise the suspicion of a muscarinic poisoning.^1,2

The acronyms SLUDGE (salivation, lacrimation, urination, diarrhea, gastric distress, and emesis) and DUMBBELS (diarrhea, urination, miosis, bradycardia, bronchorrhea, emesis, lacrimation, and salivation) may be useful memory aids for the cholinergic syndrome affecting muscarinic receptors.

Muscarine does not directly cause CNS symptoms because it does not cross the blood-brain barrier due to its chemical nature as an ionized quaternary amine. The dizziness and headache occasionally experienced by patients poisoned with muscarine are the consequence of the peripheral cardiovascular and respiratory effects.

If symptoms such as vomiting, diarrhea, and abdominal pain begin 5 hours or more after ingestion, poisoning with the potentially life-threatening or severe mushrooms such as the cyclopeptide (Amanita phalloides) or orellanine (Cortinarius mushrooms) groups, which can produce hepatic or renal failure, respectively, should be considered.^6,7,3,4,5 Amanita smithiana (allenic norleucine group) found in the Northwestern US can also be nephrotoxic but has an onset of gastrointestinal distress within 1-12 12 hours after ingestion.¹¹ For mushroom ingestions in the Pacific Northwest region of the United States, patients who have early-onset symptoms and remain symptomatic should be fully evaluated in a hospital until the mushroom identity is confirmed or the patient’s condition improves.⁵

• Vital signs
• Pulse - Bradycardia or reflex tachycardia
  • Respiration - Unaffected to labored with shortness of breath
  • Blood pressure - Hypotension in severe cases
  • Temperature - No changes expected
• Integumentary findings
  • Facial flushing
  • Sweating
• Head, ears, eyes, nose, and throat findings
  • Pupillary constriction
  • Blurred vision
  • Excessive salivation
  • Watery eyes
• Cardiovascular symptoms
  • Bradycardia (more common)
  • Reflex tachycardia
• Respiratory signs
  • Copious bronchial secretions
  • Wheezing
  • Shortness of breath
• GI symptoms
  • Cramps
  • Vomiting
  • Increased bowel activity
  • Diarrhea
• Urinary tract symptoms
  • Increased urination
  • Bladder spasms
• Neurologic signs
  • Dizziness and headache from hypotension

Causes

• Incorrect mushroom identification by a naive forager, such as an immigrant who mistakes one of the local poisonous varieties for an edible mushroom native to his or her homeland or a novice mushroom harvester
• Intentional ingestion by a suicidal person or person attempting substance abuse
• Unintentional ingestion by a child who found mushrooms growing in yards or outdoor play areas
• Foul play in which an individual is poisoned by someone else
• Inadvertent poisoning from dried mushrooms purchased on the Internet or from other sources where the composition of the mushroom is unreliable or where the mushroom might contaminated with unknown toxic compounds

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