This list covers 30 poisons, running alphabetically from “Mad Honey” to “Mustard Gas.” They come from plants, animals, minerals, and man-made chemicals, and they turn up in surprising places, from garden pesticides and household cleaners to certain foods, medicines, and industrial products. Some are famous for their role in history or crime, while others are everyday substances that become dangerous only in the wrong dose or the wrong hands.
Poisons are substances that harm the body when they enter it through swallowing, breathing, or skin contact, even in small amounts. Cultures around the world have used them for hunting, medicine, and even political assassination for thousands of years, and mustard gas earned its grim reputation as a chemical weapon in World War I. Today, scientists study many of these same substances to develop antidotes and treatments that save lives.
Below you’ll find the table with the poison, source, effects, antidote, and description.
Poison: the common name of each substance, so you can quickly find the one you’re looking for.
Source: where the poison comes from, whether it’s a plant, animal, mineral, or manufactured product.
Effects: the main symptoms someone might experience after exposure, so you know what signs to watch for.
Antidote: the treatment or remedy used to counter the poison’s effects, when one exists.
Description: a short, plain explanation of what the poison is and why it’s notable or dangerous.
Poisons
| Poison | Source | Effects | Antidote |
|---|---|---|---|
| Mad Honey | Honey made from rhododendron nectar (grayanotoxin) | Dizziness, low blood pressure, fainting | No specific antidote; atropine for slow heart rate |
| Maitotoxin | Marine dinoflagellates (Gambierdiscus) | Severe cardiac and muscle disruption | No specific antidote; supportive care |
| Malachite Green | Industrial dye, formerly used in fish farming | Potential carcinogen, liver stress | No specific antidote; supportive care |
| Malathion | Agricultural and household insecticide | Nausea, muscle twitching, respiratory failure | Atropine and pralidoxime |
| Manchineel | Sap and fruit of the manchineel tree (Caribbean) | Blistering skin, burning throat, vomiting | No specific antidote; supportive care |
| Mandrake | Root of the mandrake plant | Hallucinations, delirium, rapid heartbeat | Physostigmine |
| Mayapple | Mayapple roots, leaves, and unripe fruit | Severe vomiting, diarrhea | No specific antidote; supportive care |
| MDMA (Ecstasy) | Synthetic recreational drug | Hyperthermia, serotonin syndrome, cardiac strain | No specific antidote; supportive care and cooling |
| Melamine | Industrial chemical illegally added to milk and pet food | Kidney stones, kidney failure | No specific antidote; supportive care |
| Mercuric Chloride | Industrial disinfectant, historic poison | Corrosive burns, kidney failure | Chelation therapy (DMSA or DMPS) |
| Mercury | Thermometers, dental amalgam, contaminated fish | Neurological damage, tremors, kidney failure | Chelation therapy (DMSA or DMPS) |
| Mescal Bean | Seeds of the Texas mountain laurel | Nausea, seizures, respiratory depression | No specific antidote; supportive care |
| Metaldehyde | Slug and snail pellets | Seizures, drooling, liver damage | No specific antidote; supportive care |
| Methanol | Wood alcohol, bootleg spirits, windshield fluid | Blindness, metabolic acidosis, death | Ethanol or fomepizole |
| Methomyl | Agricultural insecticide | Sweating, muscle twitching, respiratory failure | Atropine and pralidoxime |
| Methyl Bromide | Fumigant gas for pest control | Headache, seizures, lung damage | No specific antidote; supportive care |
| Methyl Isocyanate | Industrial chemical used in pesticide manufacturing | Lung damage, blindness, death | No specific antidote; supportive care |
| Methyl Salicylate | Oil of wintergreen, muscle-rub ointments | Vomiting, ringing ears, seizures | Sodium bicarbonate (urine alkalinization), supportive care |
| Methylene Chloride | Paint strippers, industrial solvents | Dizziness, carbon monoxide buildup, cardiac arrest | No specific antidote; oxygen and supportive care |
| Methylmercury | Contaminated fish and seafood | Neurological damage, developmental harm | Chelation therapy |
| Mezereon | Berries and bark of Daphne mezereum | Burning mouth, vomiting, blistering | No specific antidote; supportive care |
| Microcystin | Toxic blue-green algae blooms | Liver damage, abdominal pain | No specific antidote; supportive care |
| Milkweed | Sap and leaves of the milkweed plant | Vomiting, weakness, irregular heartbeat | No specific antidote; supportive care |
| Mistletoe | Berries and leaves of the mistletoe plant | Vomiting, diarrhea, blurred vision | No specific antidote; supportive care |
| Monkshood | All parts of the Aconitum plant | Numbness, cardiac arrhythmia, paralysis | No specific antidote; cardiac supportive care |
| Moonseed | Berries of the Canada moonseed vine | Seizures, vomiting | No specific antidote; supportive care |
| Morphine | Opium poppy derivative, medical painkiller | Respiratory depression, sedation, death in overdose | Naloxone |
| Muscarine | Certain mushrooms, including Inocybe and Clitocybe species | Sweating, salivation, blurred vision, slowed heart rate | Atropine |
| Muscimol | Fly agaric mushroom (Amanita muscaria) | Drowsiness, confusion, hallucinations | No specific antidote; supportive care |
| Mustard Gas | Chemical warfare agent | Severe skin blistering, lung damage, blindness | No specific antidote; decontamination and supportive care |
Descriptions
Mad Honey
A rare honey containing grayanotoxin from rhododendron flowers that causes dizziness and a dangerously slow heartbeat when eaten in excess.
Maitotoxin
One of the most potent natural toxins known, produced by tiny marine organisms and linked to ciguatera fish poisoning in tropical reef fish.
Malachite Green
A vivid green dye once used to treat fungal infections on farmed fish, now restricted in food animals due to cancer concerns.
Malathion
A widely used organophosphate pesticide that disrupts nerve signaling in insects and can cause similar poisoning in humans at high exposure.
Manchineel
Nicknamed the “little apple of death,” this Caribbean tree’s sap and fruit cause severe blistering and internal burning on contact or ingestion.
Mandrake
A root steeped in folklore and old medicine, containing alkaloids that can trigger vivid hallucinations and dangerous confusion if consumed.
Mayapple
A woodland plant whose unripe fruit and other parts contain podophyllotoxin, causing intense stomach upset if eaten before the fruit ripens.
MDMA (Ecstasy)
A synthetic party drug that can overheat the body and overload the nervous system, turning fatal in overdose or hot, crowded settings.
Melamine
A nitrogen-rich plastic chemical infamous for being fraudulently added to food products to fake protein content, damaging the kidneys.
Mercuric Chloride
A highly corrosive mercury compound once used as an antiseptic, capable of severe internal burns and kidney failure if swallowed.
Mercury
A shiny liquid heavy metal that damages the nervous system and kidneys when inhaled as vapor or eaten via contaminated seafood.
Mescal Bean
The bright red seeds of this ornamental tree contain a potent alkaloid that can cause seizures and breathing trouble if chewed.
Metaldehyde
A common garden pesticide for slugs and snails that can cause seizures and organ damage if accidentally eaten by pets or children.
Methanol
A toxic alcohol the body converts into formic acid, causing blindness and potentially fatal acidosis when swallowed, often in tainted homemade liquor.
Methomyl
A fast-acting carbamate pesticide that disrupts nerve signals in pests and can trigger similar symptoms in people exposed to it.
Methyl Bromide
A colorless fumigant gas once common in agriculture, capable of severe neurological and respiratory harm if inhaled in enclosed spaces.
Methyl Isocyanate
A highly reactive industrial gas that caused thousands of deaths in the 1984 Bhopal disaster by severely damaging lungs and eyes.
Methyl Salicylate
A concentrated oil used in muscle-ache rubs that can cause life-threatening salicylate poisoning if swallowed, especially by young children.
Methylene Chloride
A common solvent in paint strippers that the body converts into carbon monoxide, posing serious risk in poorly ventilated spaces.
Methylmercury
An organic form of mercury that builds up in fish and can cause lasting nerve and developmental damage, especially in unborn children.
Mezereon
An ornamental shrub whose bright berries and bark contain irritant compounds that burn the mouth and digestive tract if eaten.
Microcystin
A toxin released by harmful algae blooms in lakes and ponds that can seriously damage the liver if contaminated water is swallowed.
Milkweed
A plant beloved by monarch butterflies that contains heart-affecting compounds, toxic to livestock and pets if grazed in large amounts.
Mistletoe
A festive holiday plant whose berries and leaves can cause stomach upset and, in larger amounts, more serious symptoms.
Monkshood
Also called wolfsbane, this striking blue-flowered plant contains aconitine, one of the most potent plant toxins affecting the heart.
Moonseed
A woodland vine whose berries closely resemble wild grapes but contain alkaloids that can trigger seizures if mistakenly eaten.
Morphine
A powerful opioid painkiller derived from the opium poppy that can fatally slow breathing when taken in excessive doses.
Muscarine
A toxin in some poisonous mushrooms that overstimulates the nervous system, causing profuse sweating and a dangerously slow heartbeat.
Muscimol
A psychoactive compound in the iconic red-and-white fly agaric mushroom that causes drowsiness and vivid hallucinations when eaten.
Mustard Gas
A notorious chemical weapon from World War I that causes painful blistering of skin, eyes, and airways on contact.