There are some HERBS which really are known to cause DEATH, when even just used. They negatively interact with the life of most MAMMALS (people especially, but also potentially other animals, like horses, dogs, and cats). The following information was gleened from a variety of sources, including: pubmed, nih, who (world health organization), FDA, scribd, webmd, herbal PDR, abstract searches, and a variety of sources over the years. These herbs are considered the "MOST DANGEROUS herbs."
Arnica ~ is considered poisonous and has caused death. When taken by mouth it can also cause irritation of the mouth and throat, stomach pain, vomiting, diarrhea, skin rashes, shortness of breath, a fast heartbeat, an increase in blood pressure, heart damage, organ failure, increased bleeding, coma, and death. However, Arnica is still often listed as an ingredient in homeopathic products. Special Precautions & Warnings during Pregnancy and breast-feeding: Don't take arnica by mouth or apply to the skin if you are pregnant or breast-feeding. It is considered UNSAFE by most scientific researchers.
Autumn Crocus ~ Autumn crocus is UNSAFE. It is considered a poison, and can cause burning of the mouth and throat, vomiting, diarrhea,
liver and kidney problems, blood disorders, nerve problems, shock, organ failure, and death. There have been reports of poisoning when autumn crocus bulbs were mistaken for onions and eaten. The amount of colchicine in autumn crocus can vary from plant to plant. It’s UNSAFE for anyone to use autumn crocus.
BUTANEDIOL (BD) ~ Butanediol is a chemical that is used to make floor stripper, paint thinner, and other solvent products. It’s illegal to sell butanediol for use as medicine. Nevertheless, butanediol is sometimes still found in products as a substitute for other illegal substances such as gamma butyrolactone (GBL) and gamma hydroxybutyrate (GHB). Unfortunately, butanediol is just as dangerous as GBL and GHB. Butanediol has been used to stimulate growth hormone production and muscle growth; and for bodybuilding, weight loss, and trouble sleeping (insomnia). Butanediol isn’t safe for anyone.
BUTTERCUP ~ (aka Apio Sardónico, Celery-Leafed Crowfoot, Cursed Crowfoot, Herbe de Feu, Herbe Sardonique, Mort aux Vaches, Ranunculus sceleratus, Renoncule à Feuilles de Céleri, Renoncule Scélérate, Sardonia.) - Poisonous buttercup is an herb. Yet, parts that grow above the ground are still sometimes used to make topical medicine. Despite serious safety concerns, poisonous buttercup is used for skin diseases such as scabies and leucoderma, a condition involving loss of color. However, Poisonous buttercup is UNSAFE for use when applied to skin. Skin contact with fresh or bruised plants can lead to blisters and burns that are difficult to heal. Touching poisonous buttercup might also increase the risk of sunburn.
Ephedra or Ma Huang ~ (aka BABASSU, BAIKAL, SKULLCAP, EPHEDRA, MANNA, MARJORAM, MORMON TEA, OREGANO, OREGON GRAPE, SALEP, TANGERINE) ~ Ephedra can cause severe life-threatening or disabling conditions in some people. Ephedra use is linked to high blood pressure, heart attacks, muscle disorders, seizures, strokes, irregular heartbeat, loss of consciousness, and death. Doses greater than 32 mg per day might more than triple the risk for bleeding within the brain (hemorrhagic stroke). The risk for serious side effects seems to be greater than any potential benefit. Ephedra is banned in the U.S.
HEMLOCK ~ (aka California Fern, Carrot Weed, Cicuta, Ciguë, Ciguë d’Athènes, Ciguë Officinale, Ciguë de Socrate, Ciguë Tachetée, Conium, Conium Maculata, Conium maculatum, Grande Ciguë, Mort aux Oies, Nebraska Fern, Poison Fool's Parsley, Poison-Hemlock, Spotted Hemlock, Tsuga, Vicaire, Wild Carrot.) - Hemlock is a very poisonous plant. In fact, all parts of the plant are toxic. Hemlock is most poisonous during the early stages of growth in the spring, but it is dangerous at all stages of growth. The poisons in hemlock are so deadly that people have died after eating game birds that had eaten hemlock seeds. Hemlock typically grows near fences, roadsides, ditches, abandoned construction sites, pastures, crops, and fields, where it can be confused with harmless plants. Accidental poisonings have occurred when people mistook the root for parsnip, leaves for parsley, or seeds for anise. All parts of hemlock, including seeds, flowers, and fruits, are UNSAFE. Hemlock is so poisonous it can cause death. If someone takes hemlock, he or she should get immediate medical attention. Side effects and toxicities include increased saliva, burning of the digestive tract, drowsiness, muscle pain, rapid swelling and stiffening of muscles, kidney damage, rapid breakdown of muscle tissue and release of muscle tissue byproducts into the blood, rapid heart rate followed by a decreased heart rate, loss of speech, paralysis, unconsciousness, heart, lung, and kidney failure, and death.
RUSTY-LEAVED RHODODENDRON ~ (aka Azalea, Laurier-Rose des Alpes, Rhododendri Ferruginei Folium, Rhododendron Alpin, Rhododendron Ferrugineux, Rhododendron ferrugineum, Rododendro, Rosage, Rose des Alpes, Rose du Diable, Rosebay, Rust-Red Rhododendron, Rusty Leaved Rhododendron, Snow Rose.) - Rusty-leaved rhododendron is a plant, considered poisonous. Rhododendron honey is known as “mad honey.” Nevertheless, the leaves are used to make medicine. Rusty-leaved rhododendron is UNSAFE. The entire plant is considered poisonous. Taking rusty-leaved rhododendron can cause weakness, dizziness, nausea, vomiting, low blood pressure, slow heartbeat, irregular heartbeat, blurred vision, impaired consciousness, chills, fainting, shock, seizure, cardiac and respiratory arrest, severe stupor, and possibly death.