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Amanita phalloides

Amanita phalloides
3.Oct.2022-Expires: 7 days - Do not archive


Correct identification of the mushroom/s is imperative for optimal risk assessment. Consider and enquire about the possibility that more than one type of mushroom was ingested. If the identity is uncertain, or the patient’s signs and symptoms differ from those listed, or are delayed in onset, seek advice from a reliable source such as your local Poisons Information Center.
Further information on unidentified mushrooms can also be found by following the below link:






Amanita phalloides


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Amanita phalloides occurs mainly in deciduous and mixed deciduous forests, especially under oak trees but also near hornbeam or beech. The fungus avoids colder localities.[1]


This mushroom is poisonous, however it may be mistaken for other edible mushrooms.


Intervention Level

Child and Adult

Medical assessment, observation, and, if appropriate, decontamination, is recommended for:
- Any ingestion of a cyclopeptide mushroom
- Exposures with intent to self-harm

Observation Period

Observation at Home

All patients require medical attention.

Medical Observation

Any patient known to have ingested this type of mushroom must be admitted for monitoring and treatment, certainly those with symptoms or deranged biochemistry.


If it is suspected that the patient has ingested cyclopeptide mushrooms, every effort should be made to get the mushroom identified by a mycologist.

When possible, a sample of the mushroom should be collected for identification. A whole mushroom, including the stalk and its base is preferable. The sample should be placed in a paper (not plastic) bag and then put in a sturdy container to protect the mushroom from damage. If the mushroom needs to be stored, it should be placed in the refrigerator, not the freezer.

Diagnostic Tests

Wieland (Meixner) Test:[2]
Determines presence of amatoxin
- Perform indoors away from sunlight and excessive heat
- Squeeze a small drop of fungus juice onto a piece of pulp paper
i.e. newspaper, phone book page
- Encircle wet stop with pencil to mark location
- Dry the spot with warm air
- Add a drop of concentrated hydrochloric acid to the dry spot
The presence of amatoxins is indicated by the formation of a blue color
False positives
- Use a control without amatoxins so false positives can be identified
- A false positive reaction can occur at high temperatures or exposure to sunlight
- Psilocybin, bufotenine, and certain terpines can give false positives[3][4]
This test is limited but can be helpful in the rapid testing in cases of suspected cyclopeptide poisoning.

Admission Criteria

Any patient who has ingested cyclopeptide mushrooms must be admitted.
Furthermore, any patient who has ingested an unknown mushroom but has features or biochemical changes indicative of cyclopeptide poisoning must be admitted.
The admission hospital will require the following resources:
Specific antidotes
Advanced care/ICU
Enhanced elimination



Any patient suspected of ingesting cyclopeptide-containing mushrooms should be admitted to hospital. Initial management consists of vigorous monitoring and replacement of expected fluid losses, which may be several liters per day.[5] Along with fluid replacement correction of metabolic disturbances such as acidosis, hypoglycemia, and electrolyte imbalances should be undertaken. The patient should be hemodynamically monitored and biochemical parameters followed closely.
Due to the low oral bioavailability of cyclopeptide mushrooms and the difficulty humans have in digesting large amounts of mushrooms, single dose activated charcoal may be given up to 12 hours following ingestion.[6][7] The use of multiple dose activated charcoal in the enhanced elimination of amatoxins is indicated up to 48 hours post-ingestion due to the extensive enterohepatic circulation of these toxins.[8] It is important that a good renal output is established during the first 48 hours following ingestion.
Supportive care is the mainstay of management. Although there is no clinically proven antidote for cyclopeptide mushroom poisoning, common therapies used have included silibinin, N-Acetylcysteine, benzylpenicillin, thioctic acid, and steroids. None of the antidotes used have undergone randomized, prospective clinical trials. Silibinin and N-Acetylcysteine appear to be the treatments of choice and should be considered in the management of these poisonings.[9][10][11][12] Efficacy has not been shown for the other therapies.[10] Benzylpenicillin, thioctic acid, and steroids are no longer recommended.[10]
Use of sedating drugs is not recommended due to their impact on the assessment of mental function/encephalopathy. Acute hepatic failure is a well-recognized concern and transplantation may be required.[13][14]
Advice should be sought from a specialist liver transplant unit
The International Normalized Ratio (INR) is greater or equal to 2 at 24 hours or, 3 at any time
Creatinine is greater or equal to 200 umol/L (2.2 mg/dL)
pH is less than or equal to 7.3 or bicarbonate less than or equal to 18 mmol/L (18 mEq/L)
Blood pressure is low after volume loading (mean arterial pressure less than or equal to 60 mmHg)
The patient becomes encephalopathic
Early discussion of patients with a liver transplant unit is essential. Advice may be given and a decision to transport dependent upon results. In general it is considered desirable to transport patients prior to development of grade 2 encephalopathy.
Emergency Stabilization
Enhanced Elimination
Supportive Care
Fluid and electrolytes


Ensure Adequate Cardiopulmonary Function

Correct Hypovolemia

Immediately establish secure intravenous access.
Profound hypotension may occur requiring volume replacement.

Hypotension in children is determined by age and systolic blood pressure
Hypotension if Systolic Blood Pressure (mm Hg) is:
0 to 28 days
< 60
1 to 12 months
< 70
1 to 10 years
< 70 + (age in years x 2)
> 10 years
< 90
Administer an isotonic crystalloid fluid
10 mL/kg IV over 5 to 10 minutes
If the systolic blood pressure does not return to the normal range, give a further 10 mL/kg body weight of the isotonic crystalloid over 5 to 10 minutes.
The intraosseous route can be used if IV access is difficult or delayed.
Administer a bolus of isotonic crystalloid fluid if systolic blood pressure is less than 100 mmHg.
Isotonic crystalloid fluid dose:
20 mL/kg IV over 5 to 10 minutes
If the systolic blood pressure does not return to the normal range, give a further 10 mL/kg body weight normal saline over 5 to 10 minutes.
The intraosseous route can be used if IV access is difficult or delayed.

Emergency Monitoring

Seizure activity
Blood pressure
Heart rate
Fluid balance
Serum electrolytes
Renal function
Liver function



Single Dose Activated Charcoal

Administer activated charcoal up to 12 hours following a potentially toxic ingestion.
Single dose activated charcoal[15]
1 to 2 g/kg orally
50 to 100 g orally



Animal studies have shown that silibinin (Milk thistle) prevents the uptake of amatoxins by hepatocytes, reducing enterohepatic circulation and therefore enhancing renal elimination. Furthermore, silibinin stimulates DNA-dependent RNA polymerases, leading to an increase in RNA synthesis.[16] However, controlled human studies are still pending. Unfortunately, silibinin is not widely available.


Silibinin is indicated in:[17]
All patients presenting with cyclopeptide mushroom ingestion

Dose and Administration

Silibinin dose:[18][19]
Initial dose 5 mg/kg IV over 1 hour
Maintenance dose of 20 mg/kg as a continuous infusion
Initial dose 5 mg/kg IV over 1 hour
Maintenance dose of 20 mg/kg as a continuous infusion
Treatment should be continued for up to 72 hours, or until significant declines in INR and liver function tests are apparent.


Documented hypersensitivity to silibinin.

Recommended doses could be administered during pregnancy without being harmful to the fetus.[20]

Adverse Effects

Silibinin appears to be well tolerated. However the following adverse effects have been reported following administration:[21][10]
Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain)
Intermittent episodes of sweating


Animal studies indicate that sublethal doses of amatoxins deplete hepatic glutathione content.[22] N-acetylcysteine is thought to serve as a glutathione precursor and consequently, the administration of N-acetylcysteine in cyclopeptide mushroom poisoning may prevent reduced glutathione levels and subsequent hepatocellular damage.[11][23] Additionally N-acetylcysteine has been shown to reduce morbidity and mortally in severe hepatic failure irrespective of origin.[24] It is therefore recommended in cyclopeptide mushroom poisoning.


N-acetylcysteine should be administered in:[20]
All patients presenting with cyclopeptide mushroom ingestion

Dose and Administration

While acetylcysteine is recommended to be administered intravenously in 5% dextrose in water, 1/2 normal (0.45%) saline or normal saline (0.9%) may be substituted if necessary.[25] In children there is a risk of hyponatremia with 5% dextrose alone[26] and therefore normal (0.9%) saline should be used.
It is recommended that acetylcysteine dose for children be calculated for actual body weight.
Children < 14 years old:
200 mg/kg in 7 mL/kg (up to 500 mL) of normal saline over 4 hours
Followed by 100 mg/kg in 14 mL/kg (up to 1,000 mL) of normal saline over 16 hours
Children 14 years and older:
As per adults
Closely monitor fluid and electrolyte balance.
It is recommended that acetylcysteine dose for adults be calculated for actual body weight rounded up to the nearest 10 kg with a ceiling weight of 110 kg.
200 mg/kg in 500 mL of 5% dextrose over 4 hours
Followed by 100 mg/kg in 1,000 mL of 5% dextrose over 16 hours


Acetylcysteine should be administered to pregnant patients following the standard adult regimen. Transplacental transport of acetylcysteine is not thought to be clinically significant,[30] however, delay in initiation of acetylcysteine treatment is associated with increased incidence of spontaneous abortion and fetal death.[31] Acetylcysteine is not considered teratogenic.[32]

Adverse Effects

Anaphylactoid Reaction
Six to 23% of patients receiving IV acetylcysteine develop an anaphylactoid reaction.[33][34] These do not represent an immunological (allergic) reaction; rather, they are thought due to a direct dose-dependent effect on histamine release and generally occur within the first two hours of an infusion.
History of previous anaphylactoid reaction to acetylcysteine does not contraindicate use. If there is concern of recurrence of the reaction the patient may be pre-treated 15 minutes before commencement of the infusion with an antihistamine.[35]
Effects range from mild flushing to urticaria, angioedema, or bronchospasm. Hypotension may occasionally occur. Asthmatics appear more at risk. However, effects are usually easily managed and there is no reason to withhold acetylcysteine from any patient when indicated.[35]
Hyponatremia has been reported in children if administered acetylcysteine in 5% dextrose following adult protocols for dilution of infused dose.[26]


Cyclopeptide mushroom ingestion produces the Phalloides syndrome, which typically exhibits a quadriphasic course, and appears to be dose related.
Phase 1 and 3 are latent periods where the patient generally feels relatively well. Phase 2 begins approximately 12 hours after mushroom ingestion and consists predominantly of severe gastrointestinal symptoms, which leads to significant water and electrolyte loss. The final phase is hepatorenal, where severe hepatotoxicity may occur and hepatic and renal failure can ensue. In fatal cases, death may occur six to 16 days following ingestion.[36]

Routes of Exposure

Cyclopeptide mushrooms are usually ingested in fresh condition. Poisoning typically occurs as a result of amateur mushroom gatherers mistaking the mushrooms for various edible varieties. The toxins remain stable when boiled, thus poisoning is possible whether the mushrooms are eaten raw or cooked.[37]

Onset/Duration of Symptoms

Symptoms following the ingestion of amatoxin-containing mushrooms occur in four phases.
NOTE: Time frames may vary considerably to those listed below.
Latent asymptomatic phase (< 24 hours and usually up to 12 hours post-ingestion)
No symptoms
Gastrointestinal phase (6 to 24 hours post-ingestion)
Abdominal pain
Severe diarrhea
Electrolyte disturbances
Acid-base disturbance
Period of well-being (24 to 48 hours post-ingestion)
Hepatic and renal function deteriorates
Hepatic phase (3 to 5 days post-ingestion)
LFT increases
Acute hepatic failure
Acute renal failure
In fatal cases, death may occur 6 to 16 days following ingestion due to hepatic and/or renal failure.[36]

Severity of Poisoning

Mild Cyclopeptide ToxicityModerate Cyclopeptide ToxicitySevere Cyclopeptide Toxicity
Abdominal pain
Electorlyte imbalances
Right upper quadrant tenderness
Renal dysfunction
Metabolic acidosis
Fulminant hepatic failure
Acute renal failure
Hepatic encephalopathy


[1] Bresinsky A, Besl H. A colour atlas of poisonous fungi. London: Wolfe Publishing Ltd; 1990. p. 26-35.
[2] Benjamin DR. Mushrooms: poisons and panaceas: a handbook for naturalists, mycologists, and physicians. New York: WH Freeman and Company; 1995. p. 191-2.
[3] Beuhler M, Lee DC, Gerkin R. The Meixner test in the detection of alpha-amanitin and false-positive reactions caused by psilocin and 5-substituted tryptamines. Ann Emerg Med 2004 Aug; 44 (2): 114-20.
[4] Beutler JA, Vergeer PP. Amatoxins in American mushrooms: Evaluation of the Meixner test. Mycologia 1980; 72 (6): 1142-9.
[5] Pinson CW, Daya MR, Benner KG, Norton RL, Deveney KE, Ascher NL, Roberts JP, Lake JR, Kurkchubasche AG, Ragsdale JW. Liver transplantation for severe Amanita phalloides mushroom poisoning. Am J Surg 1990 May; 159 (5): 493-9.
[6] Vesconi S, Langer M, Iapichino G, Costantino D, Busi C, Fiume L. Therapy of cytotoxic mushroom intoxication. Crit Care Med 1985 May; 13 (5): 402-6.
[7] Bergoz R. Trehalose malabsorption causing intolerance to mushrooms. Report of a probable case. Gastroenterology 1971 May; 60 (5): 909-12.
[8] Busi C, Fiume L, Costantino D, Langer M, Vesconi F. Amanita toxins in gastroduodenal fluid of patients poisoned by the mushroom, Amanita phalloides. [Letter] N Engl J Med 1979 Apr 5; 300 (14): 800.
[9] Karlson-Stiber C, Persson H. Cytotoxic fungi--an overview. Toxicon 2003 Sep 15; 42 (4): 339-49.
[10] Enjalbert F, Rapior S, Nouguier-Soule J, Guillon S, Amouroux N, Cabot C. Treatment of amatoxin poisoning: 20-year retrospective analysis. J Toxicol Clin Toxicol 2002; 40 (6): 715-57.
[11] Montanini S, Sinardi D, Pratico C, Sinardi AU, Trimarchi G. Use of acetylcysteine as the life-saving antidote in Amanita phalloides (death cap) poisoning. Case report on 11 patients. Arzneimittelforschung 1999 Dec; 49 (12): 1044-7.
[12] Roberts DM, Hall MJ, Falkland MM, Strasser SI, Buckley NA. Amanita phalloides poisoning and treatment with silibinin in the Australian Capital Territory and New South Wales. Med J Aust 2013 Jan 21; 198 (1): 43-7.
[13] Panaro F, Andorno E, Morelli N, Casaccia M, Bottino G, Ravazzoni F, Centanaro M, Ornis S, Valente U. Liver transplantation represents the optimal treatment for fulminant hepatic failure from Amanita phalloides poisoning. [Letter] Transpl Int 2006 Apr; 19 (4): 344-5.
[14] Araz C, Karaaslan P, Esen A, Zeyneloglu P, Candan S, Torgay A, Haberal M. Successful treatment of a child with fulminant liver failure and coma due to Amanita phalloides poisoning using urgent liver transplantation. Transplant Proc 2006 Mar; 38 (2): 596-7.
[15] Fountain JS, Beasley DM. Activated charcoal supercedes ipecac as gastric decontaminant. N Z Med J 1998 Oct 23; 111 (1076): 402-4.
[16] Hruby K, Csomos G, Fuhrmann M, Thaler H. Chemotherapy of Amanita phalloides poisoning with intravenous silibinin. Hum Toxicol 1983 Apr; 2 (2): 183-95.
[17] Floersheim GL. Treatment of human amatoxin mushroom poisoning. Myths and advances in therapy. Med Toxicol 1987 Jan-Feb; 2 (1): 1-9.
[18] Murray L, Little M, Pascu O, Hoggett K. Toxicology handbook. 3rd ed. Sydney, Australia: Elsevier; 2015. p. 51.
[19] Hoffman RS, Howland MA, Lewin NA, Nelson LS, Goldfrank LR, editors. Goldfrank’s toxicologic emergencies. 10th ed. New York: McGraw-Hill; 2014. p. 1515-6.
[20] Boyer JC, Hernandez F, Estorc J, De La Coussaye JE, Bali JP. Management of maternal Amanita phalloides poisoning during the first trimester of pregnancy: a case report and review of the literature. Clin Chem 2001 May; 47 (5): 971-4.
[21] An adverse reaction to the herbal medication milk thistle (Silybum marianum). Adverse Drug Reactions Advisory Committee. Med J Aust 1999 Mar 1; 170 (5): 218-9.
[22] Kawaji A, Sone T, Natsuki R, Isobe M, Takabatake E, Yamaura Y. In vitro toxicity test of poisonous mushroom extracts with isolated rat hepatocytes. J Toxicol Sci 1990 Aug; 15 (3): 145-56.
[23] Chyka PA, Butler AY, Holliman BJ, Herman MI. Utility of acetylcysteine in treating poisonings and adverse drug reactions. Drug Saf 2000 Feb; 22 (2): 123-48.
[24] Harrison PM, Wendon JA, Gimson AE, Alexander GJ, Williams R. Improvement by acetylcysteine of hemodynamics and oxygen transport in fulminant hepatic failure. N Engl J Med 1991 Jun 27; 324 (26): 1852-7.
[25] Cumberland-Pharmaceuticals. Acetadote (Acetylcysteine) Injection - Package Insert. Nashville TN: Cumberland Pharmaceuticals Inc, 2011: [Cited 2012 Jan 27]. URL: http://www.acetadote.net
[26] Sung L, Simons JA, Dayneka NL. Dilution of intravenous N-acetylcysteine as a cause of hyponatremia. Pediatrics 1997 Sep; 100 (3 Pt 1): 389-91.
[27] Chiew AL, Reith D, Pomerleau A, Wong A, Isoardi KZ, Soderstrom J, Buckley NA. Updated guidelines for the management of paracetamol poisoning in Australia and New Zealand. Med J Aust 2020 Mar; 212 (4): 175-183.
[28] McNulty R, Lim JME, Chandru P, Gunja N. Fewer adverse effects with a modified two-bag acetylcysteine protocol in paracetamol overdose. Clin Toxicol (Phila) 2018 Jul; 56 (7): 618-621.
[29] Wong A, Graudins A. Simplification of the standard three-bag intravenous acetylcysteine regimen for paracetamol poisoning results in a lower incidence of adverse drug reactions. Clin Toxicol (Phila) 2016; 54 (2): 115-9.
[30] Selden BS, Curry SC, Clark RF, Johnson BC, Meinhart R, Pizziconi VB. Transplacental transport of N-acetylcysteine in an ovine model. Ann Emerg Med 1991 Oct; 20 (10): 1069-72.
[31] Riggs BS, Bronstein AC, Kulig K, Archer PG, Rumack BH. Acute acetaminophen overdose during pregnancy. Obstet Gynecol 1989 Aug; 74 (2): 247-53.
[32] Janes J, Routledge PA. Recent developments in the management of paracetamol (acetaminophen) poisoning. Drug Saf 1992 May-Jun; 7 (3): 170-7.
[33] Mant TG, Tempowski JH, Volans GN, Talbot JC. Adverse reactions to acetylcysteine and effects of overdose. Br Med J (Clin Res Ed) 1984 Jul 28; 289 (6439): 217-9.
[34] Bailey B, McGuigan MA. Management of anaphylactoid reactions to intravenous N-acetylcysteine. Ann Emerg Med 1998 Jun; 31 (6): 710-5.
[35] Schmidt LE, Dalhoff K. Risk factors in the development of adverse reactions to N-acetylcysteine in patients with paracetamol poisoning. Br J Clin Pharmacol 2001 Jan; 51 (1): 87-91.
[36] Fineschi V, Di Paolo M, Centini F. Histological criteria for diagnosis of amanita phalloides poisoning. J Forensic Sci 1996 May; 41 (3): 429-32.
[37] Yocum RR. New laboratory scale purification of beta-amanitin from American Amanita phalloides. Biochemistry 1978 Sep 5; 17 (18): 3786-9.

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