This list covers 15 poisons, running alphabetically from “Jack-in-the-Pulpit” to “Juglone.” They come from plants, fungi, venomous animals, and even a tainted tonic from the past, and most people run into them through gardens, wild foraging, houseplants, or the occasional insect or snake encounter rather than everyday life.
Poisons are substances that can injure, sicken, or kill a living thing, sometimes in surprisingly small amounts. Several entries here have left a real mark on history: jimmyweed once caused deadly “milk sickness” in people who drank contaminated milk, an illness believed to have killed Abraham Lincoln’s mother.
Below you’ll find the table with the poison, source, effects, antidote, and description for each entry.
Poison: the common name of each poisonous plant, animal, or substance, so you can quickly spot which entry you’re reading about.
Source: where the poison actually comes from, such as a plant, fungus, venomous animal, or chemical compound, so you understand its origin.
Effects: the symptoms or physical reactions the poison typically causes, giving you a quick sense of the danger it poses.
Antidote: the treatment or response used against the poison, including cases where no specific antidote exists and only supportive care helps.
Description: a short, plain-language overview of the poison, with background details and an interesting fact that helps it stick in memory.
Poisons
Poison
Source
Effects
Antidote
Jack-in-the-Pulpit
Plant (Arisaema triphyllum)
Burning mouth, throat swelling
Milk or water to soothe; medical care if severe
Jack-o’-Lantern Mushroom
Fungus (Omphalotus illudens)
Severe vomiting, cramping, diarrhea
Supportive care, fluids
Jamaica Ginger (Jake)
Chemical contaminant (triorthocresyl phosphate)
Nerve damage, limb paralysis (“jake leg”)
None; permanent nerve damage, supportive care
Jararaca
Snake venom (Bothrops jararaca)
Uncontrolled bleeding, tissue death, shock
Antivenom
Japanese Giant Hornet
Insect venom (Vespa mandarinia)
Intense pain, tissue damage, allergic shock
Epinephrine, supportive care
Japanese Yew
Plant (Taxus cuspidata)
Cardiac arrhythmia, sudden collapse
No specific antidote; cardiac support
Jatropha
Plant (Jatropha curcas)
Vomiting, diarrhea, dehydration
Supportive care, fluids
Jellyfish, Box
Animal venom (Chironex fleckeri)
Excruciating pain, cardiac arrest
Box jellyfish antivenom
Jequirity Bean
Plant seed (Abrus precatorius)
Multi-organ failure
None; supportive care only
Jerusalem Cherry
Plant (Solanum pseudocapsicum)
Nausea, vomiting, drowsiness
Supportive care
Jervine
Plant alkaloid (Veratrum californicum)
Birth defects, nausea
None; avoidance during pregnancy
Jessamine, Yellow
Plant (Gelsemium sempervirens)
Muscle weakness, respiratory failure
No specific antidote; supportive/respiratory care
Jimmyweed
Plant (Isocoma pluriflora)
Tremors, vomiting, “milk sickness”
Supportive care
Jimsonweed
Plant (Datura stramonium)
Delirium, hallucinations, rapid heartbeat
Physostigmine
Juglone
Chemical (walnut tree compound)
Wilting and death in sensitive plants; laminitis in horses
Removal from exposure
Descriptions
Jack-in-the-Pulpit
A woodland plant whose roots and leaves are packed with needle-like calcium oxalate crystals. Chewing any part causes an intense burning sensation in the mouth and throat, though it’s rarely life-threatening.
Jack-o’-Lantern Mushroom
An orange, gilled mushroom often mistaken for edible chanterelles. It glows faintly in the dark and contains illudin toxins that trigger violent gastrointestinal illness within hours of eating it.
Jamaica Ginger (Jake)
A Prohibition-era herbal tonic that was adulterated with a toxic industrial chemical to dodge alcohol bans. Tens of thousands of Americans developed permanent leg paralysis after drinking it in the 1930s.
Jararaca
A venomous pit viper native to South America whose bite causes severe bleeding and swelling. Its venom is famous for leading scientists to develop the first ACE inhibitor blood pressure drugs.
Japanese Giant Hornet
Also called the “murder hornet,” this giant insect delivers an unusually large, painful venom dose. Multiple stings can cause organ damage, and a handful of people die from encounters each year in Japan.
Japanese Yew
An ornamental evergreen shrub whose needles and seeds contain taxine alkaloids that disrupt heart rhythm. Eating even a small amount can cause sudden cardiac arrest in humans and animals.
Jatropha
A shrub grown for biodiesel whose seeds look deceptively like nuts. The seeds contain curcin, a toxin that causes intense vomiting and diarrhea if just a few are eaten.
Jellyfish, Box
Found in warm coastal waters of the Indo-Pacific, this jellyfish carries venom potent enough to stop a human heart within minutes. It’s considered one of the most venomous marine creatures alive.
Jequirity Bean
Also called the rosary pea, its bright red-and-black seeds contain abrin, one of the deadliest natural toxins known. A single well-chewed seed can be fatal within days.
Jerusalem Cherry
A popular ornamental houseplant grown for its cheerful orange berries, which contain solanine. The berries are mildly toxic and especially risky for curious children and pets.
Jervine
A steroidal alkaloid found in false hellebore that famously causes cyclopia (a single-eye birth defect) in lambs when pregnant sheep graze on the plant. It remains a key tool in developmental biology research.
Jessamine, Yellow
Despite its cheerful yellow flowers and sweet scent, this vine contains gelsemine, a potent alkaloid that can paralyze breathing muscles. Even nectar collected by bees from it can sicken people.
Jimmyweed
A rangeland shrub containing tremetol, a toxin that passes into the milk of grazing livestock. Drinking contaminated milk historically caused deadly “milk sickness,” including the illness that killed Abraham Lincoln’s mother.
Jimsonweed
A weedy plant with trumpet-shaped flowers found across roadsides and fields. All parts contain anticholinergic alkaloids that cause vivid hallucinations, confusion, and dangerously elevated heart rate if ingested.
Juglone
A natural chemical produced by walnut trees to suppress competing plants. It isn’t a human poison, but it’s toxic to many garden plants and can cause painful hoof inflammation in horses bedded on walnut shavings.
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