Hawthorn trees (Crataegus species) are common deciduous shrubs or small trees known for their ornamental qualities, attractive spring flowers, and small, apple-like fruits called “haws.” Found across Europe, North America, and Asia, hawthorn has a long history of use in herbal medicine and food preparation. The question of whether it is poisonous is nuanced: the plant is not entirely toxic, but specific parts contain compounds that can be harmful if ingested improperly.
Identifying the Potential Danger: Toxic Components
The danger in hawthorn lies primarily within its seeds (or pits), not the fleshy part of the berry. These seeds, similar to those of apples and cherries, contain cyanogenic glycosides, specifically amygdalin. These compounds are not inherently poisonous but become toxic when metabolized.
When the seeds are chewed, crushed, or broken down during digestion, enzymes convert the glycosides into hydrogen cyanide. Hydrogen cyanide is a rapid-acting poison that interferes with the body’s ability to use oxygen at the cellular level. While trace amounts may be present in young leaves, the seeds contain the most concentrated amount of these compounds.
Toxicity Risks for Humans and Pets
The actual risk of poisoning from eating hawthorn berries is low, especially for humans who swallow the fruit whole. The hard outer shell of an unbroken seed prevents the release of cyanogenic glycosides, allowing the seed to pass through the digestive system harmlessly. The danger increases significantly when multiple seeds are thoroughly chewed or ground up before being swallowed, triggering the cyanide-releasing reaction.
Children represent a higher risk category due to their smaller body mass and the potential for accidental ingestion of numerous berries. While a mild intestinal upset is the most common result of eating a few whole berries, chewing the seeds is a serious concern. Pets, especially dogs, face a greater risk because they are more likely to indiscriminately chew and consume larger quantities of fallen leaves and berries, potentially crushing the seeds. Symptoms in pets may include weakness, panting, and difficulty breathing.
Safe and Edible Uses of Hawthorn
Despite the toxic seeds, most of the hawthorn plant has been safely used for centuries in food and herbal remedies. The bright red pulp of the haw is rich in pectin and commonly used to make jellies, jams, wines, and syrups. Proper preparation involves removing the seeds entirely after cooking the fruit to ensure safety.
The young leaves and flowers are also traditionally consumed, sometimes brewed into an herbal tea. Extracts from the leaves, flowers, and berries are widely used in herbal medicine, primarily for their cardiovascular benefits, such as supporting heart function and circulation. These preparations concentrate beneficial compounds like flavonoids while deliberately excluding the toxic seeds.
What to Do Following Ingestion
If a person or pet has ingested hawthorn seeds, monitoring for symptoms of cyanide poisoning is necessary, though the risk is low unless many seeds were chewed. Initial signs of toxicity in humans include weakness, headache, confusion, nausea, and vomiting. More severe symptoms may progress rapidly to difficulty breathing, seizures, loss of consciousness, and cardiac arrest.
For pets, owners should watch for similar signs like excessive panting, weakness, physical distress, or collapse. The immediate step following any suspected ingestion of crushed hawthorn seeds is to contact a medical professional, such as the national Poison Control Center, or an emergency veterinarian. Providing details about the amount consumed and whether the seeds were chewed helps assess the risk. Preventative measures include clearing fallen berries from areas accessible to pets and children, and supervising young children when they are near the tree.