Is Lily of the Valley Poisonous? Toxicity Guide for Pets and People

Lily of the valley is extremely toxic and potentially fatal. Every part of the plant, including the leaves, flowers, berries, and even the water in a vase containing cut stems, contains cardiac glycosides called cardenolides. Dogs, cats, horses, and humans are all at serious risk. This is not a borderline case. Any confirmed or suspected ingestion requires immediate emergency contact with a vet or poison control center. Do not wait for symptoms to appear.

Why Lily of the Valley Is So Dangerous

The toxicity of Convallaria majalis comes from cardenolides, primarily convallotoxin, convallarin, and related compounds. These cardiac glycosides interfere directly with the heart’s electrical system by blocking the sodium-potassium pump in cardiac muscle cells. The result is disrupted heart rhythm. In sufficient doses, the arrhythmia becomes life-threatening.

What makes lily of the valley particularly hazardous is the combination of potency and accessibility. The plant is a common garden perennial valued for its fragrant spring blooms. It spreads readily, so gardens that had it years ago may still have it. The berries, which are red-orange when ripe, are attractive to children and dogs. Even small amounts of the plant matter, including leaves chewed by a small dog or berries eaten by a child, can cause serious effects.

What Part of Lily of the Valley Is Toxic?

All parts are toxic. There are no safe parts of this plant to consume.

• Leaves contain high concentrations of cardenolides throughout the growing season.
• Flowers and flower stalks are toxic.
• Berries are toxic and are often the part eaten by children because of their appearance.
• Roots are toxic.
• Water that cut lily of the valley has been kept in is also toxic and should not be consumed by people, pets, or other animals.

Symptoms of Lily of the Valley Ingestion

Symptoms can begin within 30 minutes to a few hours of ingestion. The cardiac effects may appear before or alongside the gastrointestinal signs.

Dogs and cats: Vomiting is typically the first sign. This is followed by irregular heart rate (too fast, too slow, or irregular rhythm), low blood pressure, weakness, and disorientation. Seizures, coma, and cardiac arrest can follow with significant ingestion. Cats are highly sensitive and even small exposures warrant emergency care.

Horses: Horses that graze in areas where lily of the valley grows are at risk, particularly in early spring. Signs include colic, cardiac arrhythmia, weakness, and collapse.

Humans and children: The initial symptoms are nausea, vomiting, and abdominal pain. These are followed by slowed or irregular heart rate, visual disturbances (halos, blurred vision, yellow-green color changes), headache, confusion, and low blood pressure. In serious cases, cardiac arrhythmia can become life-threatening. Children who eat the berries face the highest accidental exposure risk.

What to Do If Someone Ingests Lily of the Valley

1. Treat this as an emergency. Do not wait to see if symptoms develop.
2. Call poison control at 1-800-222-1222 (US) or your vet immediately.
3. If a pet or child has ingested the plant, go to an emergency vet or emergency room, not a regular appointment.
4. Do not induce vomiting without medical direction. In cases of cardiac glycoside poisoning, certain interventions require professional guidance.
5. Tell the vet or poison control exactly what was ingested (leaves, berries, flowers), the approximate amount, and when it happened.
6. If the person or animal is already showing heart symptoms (irregular pulse, collapse, loss of consciousness), call 911 or your emergency animal hospital immediately.

There is no specific antidote for cardenolide poisoning in pets. Treatment is supportive and aimed at stabilizing heart rhythm. Speed of treatment significantly affects outcomes.

Safe Handling Around Pets and Children

• Remove lily of the valley from gardens where dogs have access or where children play unsupervised.
• If you grow it in a separate bed, fence that area off and regularly pick up any fallen leaves or berries.
• Do not use lily of the valley in cut flower arrangements in homes with pets or small children.
• Discard the vase water from any cut lily of the valley arrangement carefully; do not let pets drink it.
• Teach children to recognize the plant and understand it is not safe to touch or taste.
• Wear gloves when handling the plant and wash hands thoroughly after.
• When buying ground cover plants at nurseries, verify that what you are purchasing is correctly identified.

Frequently Asked Questions

Is lily of the valley deadly to dogs? Yes, potentially. The cardenolides in lily of the valley directly affect heart function. Significant ingestion can cause fatal cardiac arrhythmia. This is one of the more dangerous garden plants for dogs. Any ingestion requires immediate veterinary contact.

My cat chewed a single leaf. Is that an emergency? Yes, call your vet or an emergency animal hospital right now. Cats are particularly sensitive, and the dose required to cause serious effects is low. Do not wait for symptoms.

What do lily of the valley berries look like? The berries are round and ripen from green to bright red-orange in late summer and fall. They grow in small clusters along the stem where the flowers were. They look appealing to children, which is why berry ingestion is one of the more common accidental exposures.

Is lily of the valley poisonous to touch? The primary risk is from ingestion, not skin contact. However, some people experience mild skin irritation from handling the plant. Always wash hands after touching any part of the plant.

Can lily of the valley poisoning be treated? Treatment is supportive rather than based on an antidote. Vets and physicians can manage symptoms, stabilize heart rhythm, and provide supportive care. Early treatment improves outcomes significantly. This is why getting to professional help fast matters.