Toxic Fungi of Western North America

by Thomas J. Duffy, MD

Symptoms of ibotenic/muscimol poisoning (isoxazol poisoning)

The initial symptoms of ibotenic acid poisoning are drowsiness, nausea and occasionally vomiting, usually followed an hour later with a group of central nervous system symptoms: confusion, mild euphoria, visual distortions, sensations of floating, subjective changes in bodily strength, distractibility and retrograde amnesia. True visual hallucinations such as brightly lit tunnels and swirling colors occasionally occur.

Waser tested pure muscimol on himself and noted confusion, difficulty finding the proper words, colored visual distortions and finally sleep. (106) Ibotenic acid caused only lassitude, sleep and migraine headache with the classical one-sided visual disturbance. The headache continued in milder form for two weeks. There was no nausea or vomiting, which are not constant features of this poisoning and may be due to individual sensitivity or to an undescribed toxin.

Symptoms in children do not follow the adult course, but are more grimly excitatory in form. In a review of 1 case of Amanita muscaria poisoning and 8 cases of Amanita pantherina poisoning, all in children from age 11 months up, symptoms began 30-180 minutes after ingestion. (106a) The dominant presenting features were ataxia, obtundation and lethargic to euphoric states. Physicians and nurses commonly observed myoclonic jerking and muscle fasciculation. Typical generalized tonic/clonic seizures were seen in two children and minor seizure-like activity was noted in two others. Diazepam readily controlled seizures.

Although seizures may occur with either Amanita pantherina or Amanita muscaria early in the course with adults, these neurologic symptoms are rare after puberty. In three journal reports, normal neurologic reflexes (corneal, abdominal wall and knee) were lost in poisoned adults and abnormal ones appeared (Babinski's, Chvostek’s, Trousseau’s). Neither ibotenic acid nor muscimol cause GI irritation, the cause of which remains unknown. (107,108,109)

Although children are more susceptible than adults to the more severe neurological effects, severe poisoning in adults may cause muscle fasciculations, brief muscular jerks or generalized seizures. In a report of ten heavily poisoned cases, three patients had seizures witnessed by physicians. (106a) At the second Aspen Mushroom Conference, Dr. Barry Rumack presented one adult case of massive ingestion of Amanita muscaria in which a psychotic patient developed status epilepticus (where one seizure blends into another).

Drying and cooking convert most of the ibotenic acid in these amanitas to muscimol. Only blanching and throwing out the cooking water significantly lower the toxicity.

Japanese found that muscimol in very small amounts was twenty times more effective in enhancing food flavors than sodium glutamate, the commonly used salt of glutamic acid. (54),(104)

Amanita muscaria has had a higher fatality rate than Amanita pantherina in Germany. (110) In the United States, more deaths have been reported from Amanita pantherina than from Amanita muscaria, which almost never has a fatal outcome here. (111) One particularly notorious death from Amanita muscaria, that of the diplomat, Italian Count Achilles de Vecchj in Washington, DC. at the turn of the 19th century, proved an early stimulus to American amateur mycology. (111a ) The Pacific Northwest has had 2-3 deaths over many years from Amanita pantherina. There was also one fatality from Amanita muscaria and one from what appeared to be Amanita gemmata. (16) A pot-hunter mistook Amanita muscaria for the European Amanita caesaria and ate roughly two dozen caps! The unique Amanita gemmata death occurred in a two-year-old child, who had shared a meal with her parents. She became listless, had a convulsive seizure and died.

Amanita muscaria has been eaten without symptoms in small quantities after boiling and throwing out the water. Eaten raw or nearly so, Amanita muscaria acts as a “poor man’s hallucinogen” and was very fashionable in the 60’s. However, it is far less potent in this respect than psilocybin mushrooms and much more likely to have unpleasant results. Recreational use of Amanita pantherina in California has been less frequent than in the PNW.

"Mushroom the Journal" had an educational story in its summer 1991 issue. (112) A busload of high-school students, coming back from a jazz competition mushroomed in woods near their dinner stop. Thinking to get high from Amanita muscaria they picked Amanita pantherina. They shortly began to vomit and hallucinate and even a few became semi-comatose. Three boys ended up in an intensive care unit, two others were kept overnight in hospital and six more were treated and released after ipecac and activated charcoal treatment. Oregon State police rushed the samples to Oregon Health & Science University in Portland. The university in turn got Janet Lindgren, chairman of the Toxicology Committee of the Oregon Mycological Society, out of bed at 2 a.m. The symptoms, the time of year and the fragments clearly identified the offending mushrooms as Amanita pantherina. The school temporarily suspended those, who poisoned themselves; the others hopefully learned by example.

The 18th century Siberians seem to have used Amanita muscaria to increase their feeling of strength before battle. Dr. Angus McDonald did a 1978 study in California with human volunteers using placebo capsules of whole wheat toast and capsules with dried powdered Amanita muscaria using specimens provided by the MSSF. (113) Among the symptoms was nausea, increased salivation, time changes and improved color vision. There were also auditory, visual and bodily distortions including a sensation of increased strength. Motor coordination (standing on one foot, putting nuts on bolts) was decreased, but dart throwing was not. If any conclusion can be drawn about Siberian beserkers, they probably slept before battle, wobbled around, but threw lances just as well.

The six human volunteers and McDonald himself had enough in the way of unpleasant symptoms to outweigh any pleasant feelings. Only two wanted to repeat the experiment at 1/3 of the dose used in the study.