Does not cross the blood-brain barrier significantly
Therefore produces peripheral cholinergic toxidrome without CNS effects
Does NOT inhibit acetylcholinesterase
Distinguishes from organophosphates and carbamates
Explains why pralidoxime is ineffective
Muscarine precursor release
Muscarine may be released from phosphorylated precursor upon cellular injury (Dorner et al. 2024)
Cooking does not reliably destroy muscarine
Organ effects
Cardiac — M2 receptor activation
Negative chronotropy — bradycardia
Negative dromotropy — AV conduction slowing
Hypotension from vasodilation and reduced cardiac output
Pulmonary — M3 receptor activation
Bronchospasm — smooth muscle contraction
Bronchorrhea — mucous secretion
Exocrine glands — M3 receptor activation
Salivation, lacrimation, sweating
GI tract — M3 receptor activation
Increased motility — diarrhea, cramping
Nausea and vomiting
Eyes — M3 receptor activation
Miosis — ciliary muscle spasm
Blurred vision
Classification in mushroom poisoning syndromes
White et al. 2019 classification — Group 2B autonomic toxicity
Early-onset peripheral cholinergic syndrome
Distinguishes from late-onset hepatotoxic (Group 4) and nephrotoxic (Group 6) syndromes
Therapeutic Considerations
Atropine pharmacology
Competitive antagonist at muscarinic receptors
Blocks M1, M2, M3 receptor activation by muscarine
Reverses secretory, bronchospasm, cardiac, and GI effects
Dose titration principle
Titrate to secretion control — not to heart rate
Tachycardia is expected and acceptable collateral effect
Large doses may be required — no ceiling dose
Maintenance infusion rationale
Mushroom-derived muscarine has sustained duration of action
Single bolus doses insufficient for prolonged toxin effect
10 to 20% of loading dose per hour maintains clinical effect
Decontamination evidence
Activated charcoal evidence limited to theoretical benefit
Most useful if administered within 1 hour of ingestion
Risk-benefit assessment required — airway protection first
Why pralidoxime is not indicated
Muscarine does not form covalent bond with acetylcholinesterase
Pralidoxime (oxime reactivator) has no target in muscarinic mushroom poisoning
In organophosphate poisoning, cholinesterase is inhibited — pralidoxime reactivates it
Confusion between the two syndromes may lead to inappropriate pralidoxime use
Monitoring for co-ingestion
Serial LFT monitoring at 12 and 24 hours
Detects evolving amatoxin hepatotoxicity early
Treatment window for amatoxin antidotes (silibinin) is narrow
Monitoring is mandatory if species not definitively identified
Patient Discharge Instructions
copy discharge instructions
Mushroom poisoning — home care instructions
You were treated for mushroom poisoning from a mushroom that contains a chemical called muscarine
This type of poisoning causes excessive saliva, tears, sweating, diarrhea, and stomach cramps
Your symptoms should fully resolve within 6 to 24 hours
Drink clear fluids regularly over the next 24 hours to replace lost fluids
Eat bland foods as your stomach settles — soup, crackers, rice
Rest for the remainder of the day
Medications
Take any prescribed medications as directed
Do not take any new medications without checking with your doctor or pharmacist first
Foraging safety
Do NOT eat wild-foraged mushrooms unless an expert mycologist has confirmed the species is safe
Many toxic mushrooms closely resemble edible varieties
If you have any remaining mushrooms from the same batch — do not eat them
Bring any remaining mushroom specimens to the emergency department or Poison Control Center if requested
Return to the emergency department immediately if you develop
Difficulty breathing, wheezing, or chest tightness
Return of profuse sweating, drooling, or tearing
Severe stomach cramps or vomiting that prevents fluid intake
Fainting or near-fainting
Yellowing of the skin or eyes (jaundice) — this could mean a different type of mushroom toxin affecting the liver
Dark urine or decreased urination
Confusion or unusual drowsiness
Follow-up
See your family doctor within 2 to 3 days
If your mushroom species was not fully identified, you may need a repeat blood test to check your liver function
Report the poisoning to your local Poison Control Center if you have not already done so — this helps track poisoning trends in your area
References
Guidelines and key sources
Key clinical references
Lurie Y et al. Mushroom Poisoning From Species of Genus Inocybe: A Case Series With Exact Species Identification. Clinical Toxicology. 2009. PMID 19566380
Primary case series for Inocybe muscarinic poisoning
Onset timing and atropine dosing data
White J, Weinstein SA, De Haro L et al. Mushroom Poisoning: A Proposed New Clinical Classification. Toxicon. 2019. PMID 30439442
Group 2B autonomic toxicity classification
Framework for distinguishing early vs delayed onset syndromes
Dorner S, Trottmann F, Jordan PM et al. The Fatal Mushroom Neurotoxin Muscarine Is Released From a Harmless Phosphorylated Precursor Upon Cellular Injury. Angewandte Chemie. 2024. PMID 39432715
Muscarine precursor mechanism
Xu F et al. Mushroom Poisoning From Inocybe Serotina: A Case Report With Exact Species Identification and Muscarine Detection. Toxicon. 2020. PMID 32345453
Species-confirmed case and UPLC-MS/MS muscarine detection
Deng LS et al. A New Muscarine-Containing Inocybaceae Species Discovered From a Poisoning Incident in Tropical China. Frontiers in Microbiology. 2022. PMID 35859745
Tropical region muscarinic poisoning documentation
Henretig FM, Kirk MA, McKay CA. Hazardous Chemical Emergencies and Poisonings. New England Journal of Medicine. 2019
Organophosphate vs muscarinic mushroom distinction
Atropine and pralidoxime pharmacology
Pharmacological references
FDA Drug Label — Atropine Sulfate Injection. DailyMed. Updated 2024
Approved indication includes muscarinic mushroom poisoning
Dosing ranges for adults and pediatrics
Moss MJ, Hendrickson RG. Toxicity of Muscimol and Ibotenic Acid Containing Mushrooms. Clinical Toxicology. 2019. PMID 30073844
Regional Poison Control Center 14-year case series
Ibotenic acid and muscimol differentiation from muscarine toxidrome
ICD-10 coding
ICD-10 T62.0X1A toxic effect of ingested mushrooms, accidental, initial encounter
ICD-10 T62.0X3A toxic effect of ingested mushrooms, assault, initial encounter
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.