The term “laurel” is a common name applied to diverse plants across multiple botanical families, creating confusion regarding their safety. While many species bearing the name “laurel” are harmless, others contain potent toxins that pose a serious health risk if ingested, particularly the berries. Since the physical appearance of various laurel berries can be similar, precise identification is necessary to prevent accidental poisoning. The toxicity ranges from mild gastrointestinal upset to life-threatening complications, especially in small children and pets.
Clarifying the Ambiguity: Identifying Toxic Species
Two highly toxic species frequently referred to as laurel must be avoided: Prunus laurocerasus and Kalmia latifolia. Prunus laurocerasus, commonly known as Cherry Laurel or English Laurel, is a popular evergreen shrub often planted for hedges. Its small, dark, cherry-like berries are especially dangerous because the seed inside the berry contains a high concentration of hazardous compounds. Ingestion is particularly risky for children who may be attracted to the fruit’s appearance.
The second poisonous plant is Kalmia latifolia, or Mountain Laurel, a flowering shrub native to the eastern United States. All parts of this plant, including the flowers, leaves, and dry seed capsules, contain potent toxins. Accidental consumption of the berries from either species warrants immediate medical intervention due to the severity of the toxins involved.
The Mechanism of Toxicity
The toxic effects of Cherry Laurel stem from chemical compounds known as cyanogenic glycosides (prunasin and amygdalin). These glycosides are stored within the plant’s cells, separate from an enzyme. When the tissue is crushed, chewed, or digested, the glycosides mix with the enzyme, initiating a chemical reaction.
This reaction rapidly hydrolyzes the glycosides to release hydrogen cyanide (also called prussic acid). Hydrogen cyanide is a fast-acting poison that interferes with cellular respiration, preventing the body’s cells from using oxygen. This cellular asphyxiation first affects organs with high oxygen demand, such as the brain and heart.
In contrast, Mountain Laurel’s toxicity is due to grayanotoxins. These compounds disrupt the normal function of cell membranes, particularly in the nervous and cardiovascular systems. Grayanotoxins bind to sodium channels, causing them to remain open and leading to persistent nervous system stimulation.
Symptoms and Emergency Protocol
Symptoms of poisoning from toxic laurel berries can appear rapidly, often within minutes to a few hours of ingestion. Initial signs of cyanide poisoning from Cherry Laurel include rapid breathing, dizziness, vomiting, nausea, and abdominal pain. As the body’s ability to utilize oxygen declines, severe symptoms such as confusion, unconsciousness, and respiratory failure may occur.
Mountain Laurel poisoning (grayanotoxins) presents with excessive salivation, vomiting, diarrhea, and a burning sensation in the mouth and throat. More serious effects involve the cardiac system, including an irregular or slowed heart rate and low blood pressure. Muscle weakness, tremors, and paralysis are also possible as the neurotoxin affects the nervous system.
Symptoms in Household Pets
Dogs and cats are especially vulnerable to accidental ingestion. Initial signs of laurel poisoning in pets often include excessive drooling, vomiting, and diarrhea. Following ingestion of Cherry Laurel, pets may exhibit difficulty breathing and a decline in coordination.
Grayanotoxin poisoning from Mountain Laurel can lead to pronounced neurological and cardiac signs. Owners might observe muscle spasms, profound weakness, and an abnormal heart rhythm. If any part of a toxic laurel plant is consumed or if these symptoms appear, contact a veterinarian or a Pet Poison Helpline immediately.
The immediate emergency protocol for suspected poisoning is to seek professional medical help without delay. For human exposure, call a local Poison Control Center or emergency services. Do not wait for symptoms to worsen or attempt to induce vomiting unless specifically instructed by a medical professional. Treatment typically involves supportive care, which may include administering activated charcoal or specific antidotes for severe cyanide poisoning.
Safe Varieties and Culinary Use
The safe, culinary variety often mistakenly linked to the toxic species is Laurus nobilis, known as Bay Laurel or Sweet Bay. Its dried leaves are used as a common seasoning in soups, stews, and sauces worldwide. The leaves of this true laurel are non-toxic to humans in cooking quantities, though they are usually removed before serving due to their texture.
The berries of Laurus nobilis are technically non-toxic and are sometimes used to make a spice or oil. However, they are rarely consumed raw or in large quantities. While Bay Laurel is safe for human culinary use, its leaves, bark, and berries are considered mildly toxic to household pets like dogs and cats.
Because of widespread misidentification, certainty of a plant’s identity is necessary before using any part for consumption. Relying solely on the common name “laurel” is unsafe. Only leaves from a positively identified Laurus nobilis plant should be used in the kitchen. When in doubt, assume the plant is toxic and avoid all contact and ingestion.