Are Wisteria Poisonous?

Wisterias are striking vines with their beautiful clusters of purple, pink, or white flowers that drape in cascades of color. They are a long-living plant from the legume family and closely related to flowering peas. Although you may be attracted to their colorful appearance, you may be anxious about planting them if you do not know their toxicity levels.

Wisterias are legumes with a vine habit that produce clusters of flowers and seed pods similar to pea pods. Wisteria is a toxic plant with most of the toxins concentrated in the seeds and seed pods. The toxins wisterin and lectin cause symptoms of poisoning if wisteria is ingested.

Most people would not associate beans and peas with the profuse flowering wisteria, but they are plants from the same family as these vegetables. There are nine different types of wisteria, but the most common ones are Chinese, Japanese, and American wisteria.

What Makes Wisteria Poisonous?

Wisteria contains two chemicals that are toxic, wisterin and lectin. These two compounds are found throughout the plant, including the flowers. The highest concentration of wisterin and lectin is in the seeds and seed pods.

Consuming even two seeds can cause serious illness. The number of seeds or seed pods eaten and the size of the individual will affect the severity of the toxic symptoms that are seen.

What Are The Symptoms Of Wisteria Toxicity In People?

The first signs of poisoning are usually a burning sensation in the oral membranes. Gastrointestinal symptoms occur approximately one and a half to three and a half hours after eating the wisteria seeds or seed pods. These would include stomach cramps, vomiting, bloody diarrhea, and nausea.

Neurological symptoms that include dizziness, confusion, muscle weakness, vertigo, and fainting can occur. These symptoms worsen in severity with the number of seeds or seedpods that are eaten.

Violet Wisteria
Yay Violet Wisteria

If wisteria is burnt, the smoke causes headaches and may result in some confusion and dizziness. Symptoms of wisteria poisoning usually last for twenty-four to forty-eight hours. There have been some wisteria poisoning cases reported where the individual experienced the symptoms for up to seven days.

Previous exposure to wisteria toxins can result in heightened sensitivity to further exposures. It is hoped, though, that one negative experience with wisteria will discourage anyone from eating any more wisteria seeds or seed pods.

A scientific report published in 2017 documented seven kindergarten children that ate wisteria seeds. Six of the children ate only half a seed, while one ate one whole seed. Even though the children ate such a small amount, all seven were hospitalized for a minimum of three days.

The child who ate the whole seeds had the most severe symptoms. This indicates that the quantity ingested affects the severity of the poisoning.

Is Wisteria Toxic To Dogs And Cats?

Wisteria is a plant that has caused fatal poisoning in many dogs and cats across many continents. Dogs are more commonly affected as they are more likely to chew objects they find in the garden. Some cats may be curious and also chew on a wisteria seed pod.

The results are severe poisoning with gastrointestinal and neurological symptoms. The first sign of wisteria poisoning is usually vomiting and diarrhea. This is quickly followed by tremors, muscle weakness, confusion, seizures, and death.

Dried wisteria seed pods contain less wisterin and lectin than green pods. Dry seed pods will still produce symptoms of toxicity, but these will be less severe than those produced by green pods.

If you see any troubling symptoms or suspect your pet has eaten any part of a wisteria plant, take the animal to the veterinarian immediately. The faster the animal is treated, the better the prognosis for recovery.

Can Horses be Poisoned By Wisteria?

Horses may pick up seeds and seed pods while they are grazing. There may be accidental ingestion or deliberate ingestion if there are limited food sources available. Wisteria seeds are highly toxic to horses.

Horses have very delicate gastrointestinal systems that are easily upset, causing colic. Colic is a life-threatening condition in horses and is always treated as an emergency. Wisteria and lectin cause gastrointestinal symptoms such as diarrhea and abdominal pain, which could cause the horse to die from colic.

Other symptoms seen in horses are

  1. Confusion
  2. Agitation
  3. Depression
  4. Salivation
  5. Appetite loss
  6. Extreme thirst
  7. Dehydration
  8. Seizures
  9. Collapse
  10. Death

If your horse displays signs of colic, neurological symptoms, or if you see them eat any part of a wisteria plant, call a veterinarian immediately. The horse will need to have gastric lavage and be given activated charcoal to limit the poisoning. Several medications, including strong pain killers to deal with the colic symptoms, will be required.

Is Wisteria Toxic To Birds?

Wisteria is toxic to birds, but most wild birds seem to instinctively know that they should not eat the seeds or seed pods. Wild birds may use a wisteria tree as a perch, which does not cause any toxic effects.

Why Do Gardeners Like Wisteria

Wisteria is popular with gardeners as its colorful blooms make a bold feature in the garden. It is a legume containing lectin, which allows it to improve the soil’s nitrogen content. Plants need nitrogen to grow, and so wisteria is beneficial to other plants.

wisteria flowers in japan
Yay Wisteria flowers in Japan

You may have children or pets and would like to avoid wisteria, but still have the benefits of the added nitrogen. You can choose another legume plant to fulfill this function. Beans, peas, and alfalfa are all legumes that would increase the nitrogen in the flower and vegetable beds.

Vines with colorful flowers that could be planted instead of wisteria include morning glory, clematis, Carolina jessamine, and Jasmin. A visit to a plant nursery to discuss your needs should yield many plants that could be used instead of wisteria.


Wisteria contains the toxins wisterin and lectin that cause symptoms of poisoning in people and most animals. It affects the gastrointestinal and neurological systems and can lead to death. The severity of the poisoning is related to the number of seeds or seedpods that are eaten.