Amatoxin Poisoning: Symptoms, Stages and Treatment

Amatoxin is the name for a family of mushroom toxins behind most fatal mushroom poisonings. Wikipedia describes ten known related cyclic peptides (as of 1993), each made of eight amino acids joined in a ring. The best known is alpha-amanitin.

They work by jamming RNA polymerase II, the enzyme cells use to copy genes into messenger RNA. Wikipedia describes alpha-amanitin slowing that enzyme from several thousand nucleotides a minute to a few, after which the cell's metabolism stops and the cell dies. The liver takes most of the damage, and the kidneys are hit too.

Three properties make amatoxins worse than most poisons:

• A tiny dose. Wikipedia gives a minimum lethal dose of about 0.1 mg per kg of body weight, or 7 to 10 mg for an adult, and says as little as half a mushroom cap can cause severe liver injury.
• Heat does not help. Cooking, drying and freezing do not destroy them (Wikipedia). Poison Control adds that people can be poisoned by breathing in the fumes from cooking a poisonous mushroom.
• A silent start. Nothing happens for hours, so by the time people feel ill the toxin has already reached the liver.

Wikipedia names three main genera, Amanita, Galerina and Lepiota, plus one species of Pholiotina. Species with their own pages on this site:

• Death cap, Amanita phalloides. Yes, the death cap contains amatoxins; Wikipedia estimates about 30 grams, roughly half a cap, can kill an adult.
• Destroying angel, Amanita bisporigera and western destroying angel, Amanita ocreata. All white.
• Funeral bell, Galerina marginata. A small brown mushroom on wood.
• Deadly dapperling, Lepiota brunneoincarnata.
• Fool's conecap, Conocybe filaris, a small lawn mushroom.

The fly agaric is also an Amanita, but its toxins are ibotenic acid and muscimol, not amatoxins; see fly agaric.

A 2012 review in the International Journal of Hepatology divides death cap poisoning into four stages. The timings are ranges, and individual cases vary.

• Stage 1, lag phase. No symptoms at all for 6 to 40 hours after the meal, about 10 hours on average.
• Stage 2, gut phase. Nausea, vomiting, cramping abdominal pain and severe watery diarrhoea, lasting 12 to 24 hours.
• Stage 3, apparent recovery. Around 36 to 48 hours after eating, the gut symptoms ease and people feel better while the liver and kidneys are being damaged.
• Stage 4, liver failure. From about day 4 to day 9: jaundice, failure of blood clotting, low blood sugar, acidosis and hepatic encephalopathy (confusion that can progress to coma), within 1 to 3 weeks of eating.

The third stage is the trap. A person, or a dog, who was sick overnight and seems fine the next day may be in the most dangerous part of the illness. Tom Volk of the University of Wisconsin describes the same pattern for Galerina: first symptoms 6 to 24 hours after eating, false relief around day three, organ failure on days four and five.

Usually you cannot tell early, which is why the advice is to act on the eating, not on symptoms. Poison Control warns that symptoms from poisonous mushrooms can be delayed for many hours; in the case it describes, vomiting began about 12 hours after the meal. With amatoxins, a lag of 6 to 40 hours (International Journal of Hepatology) means the meal is often forgotten by the time illness starts.

Treat any of these as an emergency and call Poison Control at 1-800-222-1222 (U.S.) now:

• Someone has eaten a wild or foraged mushroom that an expert has not identified, even if they feel fine.
• Vomiting and diarrhoea start many hours after a meal that included wild mushrooms.
• Someone who was sick after a mushroom meal feels better but has not been checked by a doctor.

Tell the hospital about the mushroom meal and when it was eaten. NAMA advises keeping specimens in paper or waxed paper, not plastic, in the fridge; keep leftovers or a whole mushroom from the same spot, and photos of where it was picked.

There is no proven antidote you can take at home, and no home remedy. Treatment happens in hospital. It aims to stop more toxin reaching the liver, support the body through the gut phase, and replace the liver if it fails. The approaches described in the sources:

• Detoxification and supportive care, including fluids through the gut phase; the 2012 International Journal of Hepatology review groups management into preliminary care, supportive measures, detoxification and liver transplantation.
• Silibinin, an extract of milk thistle given intravenously. Wikipedia calls it a potential antidote that still needs more data.
• High-dose penicillin G and N-acetylcysteine, both part of hospital protocols (International Journal of Hepatology, 2012). Wikipedia notes a 2007 study found null results for the treatments it examined, so the evidence is mixed.
• Liver transplant when the liver fails.

The data set most reviews rely on is a 20-year retrospective analysis by Enjalbert and colleagues (Journal of Toxicology: Clinical Toxicology, 2002) that pooled 2,108 hospitalised cases from North American and European literature. In that analysis, silybin, alone or in combination, and N-acetylcysteine alone had the most favourable outcomes. The choice of drugs and doses belongs to the treating doctors and poison specialists.

Yes, many people do, especially when treatment starts early. The 2012 International Journal of Hepatology review puts mortality at 10 to 20%, and Wikipedia's death cap article gives around 10 to 30%. Some survivors need a liver transplant. Outcomes depend on how early treatment starts, which is the reason to call before any symptoms appear.

Dogs are poisoned by the same mushrooms. NC State College of Veterinary Medicine reported on 22 May 2025 that two dogs had died that week after eating death caps, with vomiting and diarrhoea 6 to 12 hours after eating, a deceptive recovery, then liver failure; its clinician described the poisoning as nearly 100% fatal without treatment. NAMA notes that dogs take a special interest in death caps, possibly because of their fishy smell. If a dog may have eaten a wild mushroom, call your vet or ASPCA Animal Poison Control at (888) 426-4435 straight away. More on what to do when a dog eats a yard mushroom.

Wikipedia describes the Meixner test (also called the Wieland test), a chemical test that can detect amatoxins in a mushroom sample, and a 2020 immunoassay that detects alpha- and gamma-amanitin at 10 ng/mL. These are tools for identification work. A home test result is never a reason to eat a mushroom, or to skip calling Poison Control after someone has eaten one.