This list covers 22 poisons, from “Laburnum” to “Lysergic Acid (Ergot Alkaloids).” They come from plants, animals, chemicals, and everyday medications, and many people encounter them without realizing the danger. Some show up in gardens and pastures, others in household products, and a few even started out as medicines or veterinary drugs.
Poisons are substances that harm the body when they enter it, whether through swallowing, touching, or a bite or sting. Their effects range from mild irritation to organ failure, and some have shaped history in surprising ways. Ergot alkaloids, for example, are blamed for outbreaks of strange hallucinations and illness in medieval Europe, long before anyone understood the fungus behind them.
Below you’ll find the table with the poison, source, effects, antidote, and description for each entry.
Poison: the name of the toxic substance, whether it’s a plant, chemical, venom, or medication taken in excess.
Source: where the poison comes from or how people usually encounter it, such as a plant, animal, or product.
Effects: the symptoms someone might experience after exposure, giving you a quick sense of the danger involved.
Antidote: the treatment used to counter the poison’s effects, or a note that only supportive care is available.
Description: a short explanation that gives you context about the poison’s origin, use, or notable history.
Poisons
| Poison | Source | Effects | Antidote |
|---|---|---|---|
| Laburnum | Seeds and pods of the laburnum tree (“golden rain”) | Vomiting, drowsiness, seizures, coma | None; supportive care |
| Lachesis Venom | Bite of the bushmaster snake (Lachesis muta) | Severe pain, swelling, bleeding disorders, tissue necrosis | Antivenom |
| Lacquer Tree Sap | Sap of the Asian lacquer tree | Painful blistering skin rash, itching | None; supportive care |
| Lantana | Berries and leaves of the Lantana camara shrub | Vomiting, liver damage, sun-sensitive skin rash | None; supportive care |
| Larkspur | Young leaves and seeds of Delphinium plants | Muscle tremors, weakness, paralysis, heart failure | None; supportive care |
| Latrodectus Venom | Bite of the black widow spider | Severe muscle cramps, sweating, high blood pressure | Antivenom |
| Laudanum | Alcohol tincture of opium | Slowed breathing, sedation, coma | Naloxone |
| Lead | Old paint, pipes, batteries, contaminated soil | Abdominal pain, anemia, brain and nerve damage | Chelation therapy (EDTA, DMSA) |
| Lead Arsenate | Historical agricultural pesticide | Vomiting, organ damage, long-term cancer risk | Chelation therapy |
| Levamisole | Veterinary dewormer, common cocaine additive | Low white blood cell count, skin lesions, vasculitis | None; supportive care |
| Lewisite | Arsenic-based chemical warfare agent | Skin blistering, eye damage, lung injury | Dimercaprol (British Anti-Lewisite) |
| Lidocaine (in overdose) | Local anesthetic used in medicine and dentistry | Numbness, seizures, irregular heartbeat, cardiac arrest | Lipid emulsion therapy |
| Lily of the Valley | All parts of the Convallaria majalis plant | Nausea, vomiting, dangerous heart rhythm changes | Digoxin immune Fab |
| Lithium (in overdose) | Batteries, psychiatric medication | Tremor, confusion, kidney damage, coma | Hemodialysis |
| Lobelia | Lobelia inflata plant, sold as an herbal supplement | Nausea, tremors, rapid heartbeat, breathing difficulty | None; supportive care |
| Locoweed | Astragalus and Oxytropis plants grazed by livestock | Depression, stumbling, brain damage in animals | None |
| Locust Tree Bark | Bark, leaves, and seeds of the black locust tree | Vomiting, weakness, irregular heartbeat | None; supportive care |
| Loperamide (in overdose) | Over-the-counter anti-diarrheal medication | Irregular heartbeat, fainting, cardiac arrest | None; supportive care |
| Loxosceles Venom | Bite of the brown recluse spider | Skin necrosis, ulceration, rarely systemic illness | None; supportive care |
| Lupine | Seeds of Lupinus plants | Vomiting, breathing difficulty, nervous system effects | None; supportive care |
| Lye | Drain cleaners, soap-making chemicals | Severe chemical burns, tissue damage | None; dilution and supportive care |
| Lysergic Acid (Ergot Alkaloids) | Ergot fungus growing on rye and grains | Hallucinations, vasoconstriction, gangrene | None; supportive care |
Descriptions
Laburnum
A small ornamental tree whose bean-like seed pods contain cytisine, a toxic alkaloid that can cause severe poisoning if children mistake the pods for peas.
Lachesis Venom
Injected by one of the largest venomous snakes in the Americas, this venom disrupts blood clotting and destroys tissue around the bite site.
Lacquer Tree Sap
Related to poison ivy, this sap contains urushiol, an oily compound that triggers intense allergic skin reactions on contact.
Lantana
A common ornamental shrub whose unripe green berries contain toxins that can poison livestock and curious children who eat them.
Larkspur
A tall flowering plant common in pastures, larkspur is notorious for poisoning cattle that graze on its toxic young shoots in spring.
Latrodectus Venom
Produced by the black widow spider, this venom overstimulates nerves, causing painful whole-body muscle spasms known as latrodectism.
Laudanum
A once-common medicinal opium preparation, laudanum can suppress breathing to dangerous levels when taken in excess, much like other opioids.
Lead
A heavy metal once common in paint and plumbing, lead builds up in the body over time and is especially harmful to children’s developing brains.
Lead Arsenate
A once-widely used orchard pesticide that combines two toxic elements, lead and arsenic, leaving lasting contamination in treated soils.
Levamisole
Originally an animal deworming drug, levamisole is now infamous as a cocaine-cutting agent that can cause dangerous immune reactions in people.
Lewisite
A blister-forming chemical weapon developed for warfare, lewisite causes immediate burning pain and blistering wherever it touches skin or eyes.
Lidocaine (in overdose)
A widely used numbing medication that is safe at normal doses but can cause seizures and dangerous heart rhythms if too much enters the bloodstream.
Lily of the Valley
A fragrant, bell-flowered garden plant containing heart-affecting compounds similar to digitalis, making every part of it toxic if eaten.
Lithium (in overdose)
A mood-stabilizing medication that becomes toxic within a narrow dose range, causing tremors and confusion when blood levels climb too high.
Lobelia
Also called “Indian tobacco,” this herb contains lobeline, a nicotine-like compound that can cause serious poisoning in large amounts.
Locoweed
A range plant containing swainsonine, locoweed causes a lasting neurological illness in grazing animals commonly called “locoism.”
Locust Tree Bark
A common shade tree whose bark and seeds contain toxic proteins that can sicken livestock and people who chew on them.
Loperamide (in overdose)
A common diarrhea remedy that, when misused in very high doses, can dangerously disrupt the heart’s electrical rhythm.
Loxosceles Venom
Injected by the reclusive brown spider, this venom can destroy skin and tissue around the bite, forming a slow-healing wound.
Lupine
A purple-flowered wildflower whose seeds contain bitter alkaloids that can poison livestock and people if eaten in quantity.
Lye
Also known as sodium hydroxide, lye is a highly corrosive substance that causes immediate, severe burns to skin and the digestive tract if swallowed.
Lysergic Acid (Ergot Alkaloids)
Produced by a fungus that infects grain crops, these alkaloids caused historical epidemics of ergotism, marked by hallucinations and restricted blood flow to limbs.