Lily of the Valley (Convallaria majalis) is cherished for its delicate, bell-shaped white flowers and sweet fragrance. This perennial plant is common in shaded gardens and frequently used in floral arrangements. Despite its appealing appearance, every part of the plant is highly poisonous to both humans and animals. This includes the leaves, flowers, stems, roots, and the small red or orange berries that appear later in the season.
The Toxic Components
The toxicity of Convallaria majalis stems from compounds known as cardioactive steroid glycosides, or cardenolides. These substances, which include convallatoxin, convallamarin, and convallarin, are present throughout the plant structure.
These glycosides damage the heart by interfering with its muscular function at a cellular level. They inhibit the sodium-potassium pump (Na⁺/K⁺-ATPase enzyme) in heart muscle cells. This disruption of the ion balance affects the electrical signaling and contraction of the heart. The resulting imbalance can lead to an increase in the force of contractions coupled with a decrease in heart rhythm.
Assessing Risk from Contact and Ingestion
The risk associated with Lily of the Valley differs depending on the route of exposure: physical contact versus consumption. Simply touching the stems, leaves, or flowers carries a low systemic risk, as toxins are not easily absorbed through intact skin. However, direct contact can still provoke a localized reaction in some individuals.
Sensitive skin may react to the plant with contact dermatitis. This reaction is confined to the area of contact and is not a sign of systemic poisoning. Gardeners should wear gloves as a precaution when handling the plant to minimize skin irritation.
Ingesting any portion of the plant tissue is a serious medical emergency. The cardenolides are rapidly absorbed through the digestive tract, quickly affecting the circulatory system. Even small quantities, such as a few berries or leaves, can cause severe poisoning, particularly in small children or pets. Furthermore, water in a vase holding cut stems can absorb enough poison to be hazardous if accidentally consumed.
Recognizing Signs of Exposure
Symptoms of exposure depend on whether the plant was ingested or touched. Following consumption, initial signs often involve the gastrointestinal system as the body attempts to reject the toxins. A person may experience nausea, vomiting, stomach pain, and diarrhea shortly after ingestion.
As cardenolides are absorbed, dangerous cardiac symptoms appear. These include an irregular heartbeat, a slowing of the pulse (bradycardia), or a weak pulse that can lead to collapse. Neurological symptoms may also manifest, such as confusion, drowsiness, or visual disturbances.
When exposure is limited to physical contact, symptoms are milder and confined to the skin. The most common reaction is localized contact dermatitis. This presents as redness, itching, or a rash on the skin that was in direct contact with the plant material. The rash may evolve into small blisters or hives, but these symptoms are not accompanied by systemic poisoning effects.
Immediate Steps After Exposure
If the skin has contacted the plant, immediately and thoroughly wash the affected area. Use soap and warm water to rinse the skin for several minutes to remove any residual sap or plant material. While contact reactions are usually mild, persistent irritation or blistering should prompt a call to a health professional.
In the event of ingestion, immediate emergency action is necessary, even if the amount consumed seems minimal. Call Poison Control (1-800-222-1222 in the United States) or your local emergency services at once. Do not attempt to induce vomiting unless specifically instructed by a medical professional or poison control specialist.
While waiting, determine the amount of plant material consumed and the time of ingestion, as emergency personnel will request this information. If possible, collect a sample of the plant to aid in identification at the hospital. Swift medical intervention, which may include monitoring the heart and administering activated charcoal, is the best course of action to counteract the effects of the cardenolides.