Hydrangeas are popular ornamental shrubs known for their large, showy blooms, but all parts of the plant are toxic if ingested by humans or domestic animals. This toxicity is generally considered low in severity. All parts of the hydrangea, including the leaves, buds, and flowers, contain potentially harmful compounds. The risk is highest for curious small children and pets who may ingest the material accidentally.
The Cyanide Connection
The toxic potential of hydrangeas is attributed to cyanogenic glycosides, which are naturally occurring defense chemicals present throughout the shrub. Higher concentrations are typically found in the leaves, buds, and young flowers. Specific cyanogenic glycosides identified include hydrangin and amygdalin.
These compounds are inert while contained within the plant’s cell structure. When the plant material is chewed or digested, the cell walls break down, allowing the glycosides to interact with specific enzymes. This interaction releases hydrogen cyanide, a potent cellular toxin. Hydrogen cyanide interferes with the body’s ability to use oxygen, causing the toxic effects.
Recognizing Symptoms of Ingestion
The most common reaction in humans is a mild case of gastrointestinal distress. Symptoms often include nausea, vomiting, abdominal pain, and diarrhea, which typically resolve without severe intervention. Lethargy and increased sweating may also occur.
Severe cyanide poisoning is extremely rare and only occurs if a very large amount is consumed. Signs of this serious reaction include labored breathing, confusion, and a rapid heart rate. In the most extreme cases, seizures or circulatory problems may develop.
Pets, such as dogs and cats, are generally more susceptible due to their smaller body size and tendency to chew on plants. Common symptoms in pets mirror those in humans, primarily presenting as gastrointestinal upset, vomiting, excessive drooling, and diarrhea. Owners should also watch for signs of depression, weakness, and loss of appetite.
Emergency Response and Safe Handling
If a child or pet ingests any part of a hydrangea, immediately remove remaining plant material from their mouth and rinse the area with water. Contact a poison control center for humans or a veterinarian for pets immediately following the incident. Professional guidance is necessary, as the severity of the reaction depends heavily on the amount consumed.
Do not attempt to induce vomiting unless directed by a medical or veterinary professional. For humans, the Poison Help Line is 1-800-222-1222, and for pets, the ASPCA Animal Poison Control Center can be reached at 888-426-4435. Providing the professional with details about the part of the plant consumed and the estimated quantity is helpful for accurate assessment.
Prevention Strategies
To prevent accidental ingestion, plant hydrangeas in areas inaccessible to small children and curious pets. Utilizing fencing or raised beds can create a physical barrier. Proper disposal of pruned leaves and flowers is also advised to ensure discarded material is not accidentally consumed.