What is the appropriate emergency management for a patient who develops diarrhea and a maculopapular rash after ingesting mushrooms?

Emergency Management of Mushroom Poisoning with Diarrhea and Maculopapular Rash

Immediately initiate aggressive fluid resuscitation, perform gastrointestinal decontamination with activated charcoal if within 3-4 hours of ingestion, and administer intravenous penicillin G (300,000 to 1 million units/kg/day) plus silymarin (30-40 mg/kg/day) while urgently listing the patient for liver transplantation evaluation. 1

Initial Assessment and Stabilization

The combination of severe gastrointestinal symptoms (diarrhea) occurring within hours to a day after mushroom ingestion strongly suggests Amanita phalloides poisoning, which carries a 5-20% mortality rate even with treatment. 1, 2 The maculopapular rash may represent a separate dermatologic manifestation or concurrent condition requiring evaluation, but should not delay treatment for the life-threatening mushroom toxicity. 1

Critical early actions:

• Assess hydration status by checking for orthostatic hypotension, dry mucous membranes, mental status changes, and extremity weakness—four or more indicators suggest severe volume depletion requiring aggressive IV resuscitation. 3
• Obtain blood cultures if febrile, complete blood count, comprehensive metabolic panel (especially liver function tests and aminotransferases), and coagulation studies. 3, 1
• Initiate isotonic intravenous fluids (lactated Ringer's or normal saline) immediately for severe dehydration or shock. 4, 3

Gastrointestinal Decontamination

If the patient presents within 3-4 hours of mushroom ingestion, perform gastric lavage and administer activated charcoal (1 g/kg orally in a slurry) via nasogastric tube. 1 This window may be extended slightly given the severity of potential toxicity. 5 Even if the patient is vomiting, nasogastric administration should be attempted as the benefits outweigh risks in this life-threatening scenario. 1

Specific Antidote Therapy

Administer both penicillin G and silymarin immediately upon suspicion of Amanita poisoning—do not wait for confirmatory testing or worsening liver function. 1

• Penicillin G: 300,000 to 1 million units/kg/day intravenously, divided into continuous or frequent dosing. 1
• Silymarin (milk thistle): 30-40 mg/kg/day either intravenously (if available) or orally for 3-4 days. 1 While not FDA-approved in the United States, silymarin has been reported to be more successful than penicillin G alone, though penicillin G is more readily available in U.S. hospitals. 1, 2

The evidence for these antidotes comes from case series and expert consensus rather than randomized controlled trials, but given the high mortality without treatment, their use is strongly recommended. 1, 2

Monitoring for Hepatotoxicity

Amanita phalloides contains amatoxins that cause delayed hepatotoxicity, with fulminant hepatic failure typically developing 2-3 days after the initial gastrointestinal phase. 6, 7

Monitor closely for:

• Rising aminotransferases (levels >3,500 IU/L are highly suggestive of severe toxicity). 1
• Development of jaundice, coagulopathy, or encephalopathy indicating acute liver failure. 5, 6
• Renal function deterioration (though less common with Amanita than with Cortinarius species). 5

Transplantation Evaluation

Contact a liver transplant center immediately and list the patient for evaluation, as orthotopic liver transplantation is often the only lifesaving option in severe Amanita poisoning. 1, 2 Historically, survival rates without transplantation have been very low (5-20% mortality even with treatment), though recent reports describe complete recovery with aggressive supportive care and antidote therapy. 1, 2

Management of the Rash

The maculopapular rash requires separate evaluation but should not delay mushroom poisoning treatment:

• Obtain dermatology consultation if the rash is severe (grade 3-4), bullous, or suggests Stevens-Johnson syndrome. 1
• For mild to moderate maculopapular rash without bullae, symptomatic treatment with topical corticosteroids may suffice. 1
• Consider whether the rash could represent a drug reaction, immunotherapy-related toxicity (if applicable), or parasitic infection given the travel/exposure history. 1

Common Pitfalls to Avoid

• Do not wait for confirmatory mushroom identification or toxin levels before initiating treatment—there is no available blood test for amatoxins, and diagnosis is clinical based on history and symptoms. 1
• Do not use antimotility agents like loperamide—these are contraindicated in suspected toxic ingestions and inflammatory diarrhea. 4, 8
• Do not assume the patient is stable after initial gastrointestinal symptoms resolve—the classic biphasic presentation includes an initial GI phase followed by apparent improvement, then fulminant hepatic failure 2-3 days later. 5, 6
• Do not delay transplant evaluation—early listing is critical as deterioration can be rapid once hepatic failure develops. 1, 2

Disposition

All patients with suspected Amanita poisoning require intensive care unit admission for continuous monitoring, aggressive supportive care, and serial laboratory assessment. 1, 5 Even patients who appear to improve after initial treatment must be observed for at least 72-96 hours to detect delayed hepatotoxicity. 5, 6