Only a few commonly grown plants are very poisonous, but many others have less serious toxic effects.
Generally, poisoning is unlikely unless a plant is highly toxic or large quantities are ingested (for example, if the leaves or other components are concentrated into a paste or brewed into a tea).
Highly toxic and potentially fatal plants include castor beans and jequirity beans, poison hemlock and water hemlock, and oleander and foxglove.
Only a few plant poisons have specific antidotes, so doctors usually just treat people's symptoms.
(See also Overview of Poisoning.)
Many other plants cause less serious toxic effects (see table Moderately Poisonous Plants).
Castor and jequirity beans
Castor beans contain ricin, an extremely potent poison. Ricin has been used in assassination attempts and as a mass-casualty weapon. Castor bean seeds have a very tough shell so the bean must be chewed to release the poison.
Jequirity beans contain abrin, a related and even more potent toxin than ricin. The beans can be fatal if swallowed. Children can die after chewing only one bean.
Poisoning from castor beans or jequirity beans may cause severe vomiting and diarrhea (often bloody) after a delayed period. People later become delirious and have seizures. They may become comatose and die.
Doctors sometimes try to flush the beans out of the stomach and intestines before they are absorbed. There is no antidote but doctors give people fluids by vein (intravenous) and other care to treat their symptoms.
Hemlock
Hemlock poisoning can cause symptoms within 15 minutes. People develop a dry mouth and later a rapid heartbeat, tremors, sweating, seizures, and muscle weakness. Water hemlock may cause vomiting and diarrhea, delirium, seizures, and coma. There is no antidote but doctors give people care to treat their symptoms.
Oleander, foxglove, and lily of the valley
Some Moderately Poisonous Plants
Plant | Symptoms | Treatment |
|---|---|---|
Aloe and related plants | Gastroenteritis and kidney inflammation | Supportive care* if the plant is swallowed and flushing (irrigation) with soap and water if the skin is irritated |
Apricot, wild cherry, and peach pits and apple and other seeds (Prunus and Malus species), which contain a chemical that is converted to cyanide after being eaten—usually only if many seeds are chewed and swallowed | Symptoms of oxygen deprivation, such as nausea, dizziness, difficulty concentrating, headache, vomiting, drowsiness, and poor coordination (similar to those of cyanide poisoning) | |
Aristolochia (also called birthworts or pipevines) | Formation of scar tissue in the kidneys | Supportive care* |
Azalea | Cholinergic† symptoms | |
Calcium oxalate-containing plants, including leaves of calla lilly, dieffenbachia (dumbcane), elephant ear, jack-in-the-pulpit, philodendron, rhubarb, and many other related plants | Irritation of the mouth due to calcium oxalate crystals in the leaves | Supportive care* and rinsing the mouth with cool liquids to soothe the area and wash away the irritant |
Capsicum and related plants (hot peppers) | Irritation of the skin and mucous membranes | Supportive care* and use of milk or ice cream to help dissolve the irritant |
Delayed gastroenteritis and malfunction (failure) of many organ systems Interference with the bone marrow's ability to produce blood cells and platelets, possibly causing anemia, infection, and/or bleeding | Supportive care* | |
Deadly nightshade | Anticholinergic‡ symptoms, a high body temperature, seizures, and hallucinations | Supportive care* |
Fava beans | In people with a deficiency of the enzyme G6PD (which protects red blood cells), gastroenteritis, fever, headache, and hemolytic anemia | Supportive care* For severe anemia and poisoning, gradual removal and replacement of blood with equal volumes of fresh donor blood (exchange transfusion) considered |
Green potatoes and potato sprouts | Gastroenteritis, hallucinations, and delirium | Supportive care* |
Holly berries | Supportive care* | |
Jimsonweed | Anticholinergic‡ symptoms, a high body temperature, seizures, and hallucinations | Supportive care* |
Licorice (raw plant, not the common candy which no longer is flavored with licorice plant extract) | Too little potassium in the blood, high blood pressure, and swelling due to retention of fluid (edema) | Supportive care* |
Too much potassium in blood and abnormal heart rhythms (arrhythmias) | Supportive care* and antibodies against digitalis | |
Mistletoe | Supportive care* | |
Monkshood | A low heart rate, abnormal heart rhythms, numbness and tingling, and weakness | Supportive care* |
Nettle | Stinging and burning of the skin | Supportive care* |
Nightshade, common or woody | Gastroenteritis, hallucinations, and delirium | Supportive care* |
Nightshade, deadly | Anticholinergic‡ symptoms, a high body temperature, seizures, and hallucinations | Supportive care* |
Pennyroyal | Damage to the liver (when severe, causing jaundice, confusion, and a tendency to bleed) | |
Philodendron and related plants | Damage to the mouth due to calcium oxalate crystals in the leaves | Supportive care* and rinsing the mouth with cool liquids to soothe the area and wash away the irritant |
Poinsettia | Mild irritation if it touches the mucous membranes of the mouth, nasal passages, vagina, or urethra | Unnecessary |
Severe itching of the skin and irritation of mucous membranes | Cool compresses, antihistamines and sometimes corticosteroids | |
Pokeweed | Irritation if it touches the mucous membranes of the mouth, nasal passages, vagina, or urethra | Supportive care* |
Pothos | Damage to the mouth due to calcium oxalate crystals in the leaves | Supportive care* and use of milk or ice cream to help dissolve the crystals |
Yew | Rarely, seizures, abnormal heart rhythms, and coma | Supportive care* |
* Supportive care may include fluids given by vein (intravenously), treatments to maintain body functions (such as drugs to lower fever), drugs to increase blood pressure if it drops, and a ventilator. | ||
† Cholinergic symptoms include a slow heart rate, weakened contraction of the heart, dangerously low blood pressure, difficulty breathing (because airways are constricted), flushing, abdominal cramps, diarrhea, increased urination and salivation, watery eyes, increased sweating, and muscle cramping. | ||
‡ Anticholinergic symptoms include confusion, blurred vision, constipation, dry mouth, light-headedness, difficulty starting and continuing to urinate, and loss of bladder control. | ||
G6PD = glucose-6-phosphate dehydrogenase. | ||
More Information
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American Association of Poison Control Centers: Represents the US-based poison centers that provide 24/7 free, confidential services through the Poison Help Line (1-800-222-1222)
