Merck Manual

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Plant and Shrub Poisoning

By

Gerald F. O’Malley

, DO, Grand Strand Regional Medical Center;


Rika O’Malley

, MD, Albert Einstein Medical Center

Last full review/revision Jul 2020| Content last modified Jul 2020
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A few commonly grown plants are poisonous. Generally, poisoning is unlikely unless large quantities are ingested (for example, if the leaves and other components are concentrated into a paste or brewed into a tea) or the plant is highly toxic. Highly toxic and potentially fatal plants include castor beans, jequirity beans, poison hemlock, and water hemlock, as well as oleander and foxglove, which contain digitalis glycosides. Few plant poisonings can be cured by specific antidotes. (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 concentrated 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 more potent toxin than ricin. They can cause death after swallowing. 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.

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.

Oleander, foxglove, and lily of the valley

Oleander, foxglove, and the similar but less toxic lily of the valley can cause vomiting and diarrhea, confusion, irregular heartbeat, and high levels of potassium in the bloodstream. These plants contain a substance very similar to the heart drug digoxin. Doctors sometimes treat people who are poisoned by these plants with a drug used to treat digoxin overdose.

Table
icon

Moderately Poisonous Plants

Plant

Symptoms

Treatment

Aloe and related plants

Gastroenteritis, kidney inflammation, and skin irritation

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), 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 carbon monoxide poisoning)

For serious poisoning, hydroxocobalamin given by vein and use of a cyanide antidote kit (including amyl nitrate given by inhalation and sodium nitrite and sodium thiosulfate given intravenously)

Aristolochia (also called birthworts or pipevines)

Formation of scar tissue in the kidneys

Supportive care*

Azalea

Cholinergic† symptoms

Supportive care* and atropine

Caladium (also called elephant ear or angel's wings) and related plants

Irritation of the mouth due to calcium oxalate crystals in the leaves

Supportive care* and use of milk or ice cream to help dissolve the irritant

Capsicum and related plants (peppers)

Irritation of the skin and mucous membranes

Supportive care* and flooding the affected area with water to wash the substance away (irrigation)

Colchicine (autumn crocus, meadow saffron, or glory lily)

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*

For a very high body temperature or seizures, possibly physostigmine

Dumbcane (dieffenbachia)

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

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*

For a very high body temperature or seizures, possibly physostigmine

Licorice (raw plant)

Too little potassium in the blood, high blood pressure, and swelling due to retention of fluid (edema)

Supportive care*

Lily of the valley

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*

Sometimes sodium bicarbonate given intravenously

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*

For a very high body temperature or seizures, possibly physostigmine

Pennyroyal

Damage to the liver (when severe, causing jaundice, confusion, and a tendency to bleed)

Acetylcysteine

Philodendron and related plants

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

Poinsettia

Mild irritation if it touches the mucous membranes of the mouth, nasal passages, vagina, or urethra

Unnecessary

Poison ivy

Inflammation of the skin (dermatitis) or mucous membranes

Avoidance of known irritants; treatment of specific symptoms

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.

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