15 Common Toxic Plants

Toxic plants contain harmful chemicals and substances that can cause adverse health effects in humans and animals. While many plants are harmless, some common house and garden plants can be quite dangerous if ingested or handled improperly. Being able to identify toxic plants is an important safety skill for pet owners, parents of small children, and gardeners.

Below we have compiled a list of 15 of the most common toxic plants that should be avoided or handled with extreme care:

Castor Bean

The castor bean plant (Ricinus communis) produces colorful seeds with mottled markings that are the source of castor oil. However, the seeds contain the deadly poison ricin which can kill a human with just a few grains. All parts of the castor bean plant contain ricin and are especially toxic to children and pets. Ingestion can cause abdominal pain, vomiting, diarrhea, headaches, seizures, liver failure, and death. The seeds and leaves should never be eaten.


Oleander (Nerium oleander) is an attractive flowering bush commonly grown outdoors in warm climates. All parts of the plant are toxic, especially the leaves and seeds which contain cardiac glycosides that affect the heart. Just a few leaves can kill an adult human and even honey made from the flowers can be deadly. Oleander poisoning causes vomiting, diarrhea, erratic pulse, seizures, coma, and death from cardiac arrest. Keep oleander far away from children and pets.


Rhododendrons are very common flowering ornamental shrubs grown in gardens across North America. The leaves, flowers, and nectar contain toxic chemicals called grayanotoxins that can cause Rhododendron poisoning. Ingesting any part of the plant can bring about nausea, vomiting, weakness, breathing issues, paralysis, coma, and even death. These toxins are potent enough that honey made from the flowers can be fatal. Keep rhododendrons away from grazing livestock.

Lily of the Valley

The dainty, bell-shaped flowers of lily of the valley (Convallaria majalis) give this plant an innocent appearance. However, the leaves and red berries of this perennial flowering plant are highly poisonous and contain cardiogenic toxins. Eating any part can lead to abdominal pain, vomiting, slowing of the heart rate, blurred vision, headache, and possibly death. All parts of the plant should be kept away from pets and children.


The tubular flowers rising from the tall stalks of foxglove (Digitalis purpurea) are quite beautiful. But every part of the common garden plant foxglove is very poisonous due to naturally-occurring cardiac and steroid glycosides, particularly in the leaves. These substances can cause digestive issues, an irregular heartbeat, mental confusion, and may be fatal even in small doses. Foxglove is extremely toxic if eaten and care should be taken in gardens where they grow.

Water Hemlock

Water hemlock (Cicuta maculata) is considered one of the most poisonous plants in North America. All parts of this tall, flowering plant contain the toxin cicutoxin which affects the central nervous system. The roots are especially poisonous and ingesting even a small amount can cause seizures, nausea, abdominal cramps, tremors, kidney and liver damage, respiratory paralysis, and death. Water hemlock grows near the edges of freshwater lakes and streams, so care should be taken when around these plants.

Poison Hemlock

Not to be confused with water hemlock, poison hemlock (Conium maculatum) is another extremely toxic flowering plant in the carrot family. It contains highly poisonous alkaloids throughout the plant, especially in the roots and leaves. Accidental ingestion can result in muscle paralysis, respiratory failure, trembling, hallucinations and death in humans and animals. Poison hemlock is commonly mistaken for harmless plants like Queen Anne’s lace and wild carrots. If you see this plant with purple spots on the stems, stay far away and do not eat any part.


Many varieties of daphne plants and shrubs are commonly grown in gardens for their fragrant flowers and berries. However, the berries, leaves, bark and roots of daphnes are very poisonous if eaten and contain toxins called mezerin and daphnin. Ingesting any parts can result in diarrhea, vomiting, headaches, depressed heart rate, breathing difficulties, coma and even death in some cases. Keep daphne plants away from children and pets, and be very careful when pruning or handling these plants.

Angel’s Trumpet

Angel’s trumpet (Brugmansia) is a tropical plant with large, pendulous trumpet-shaped flowers that emit a sweet fragrance. However, every part of the angel’s trumpet is highly poisonous and contains tropane alkaloids that can cause scary hallucinations along with serious health effects. Angel’s trumpet can cause digestive issues, erratic heart rate, paralysis, confusion, seizures, coma and possibly death when ingested by humans or animals. These plants should not be kept in homes with kids or pets.


The beautiful blue or purple flowers of monkshood (Aconitum) rise from tall stalks above deeply cut green leaves, making it a popular garden plant. But monkshood is extremely toxic due to the alkaloids contained in the roots, leaves, flowers and seeds. This substance is a fast-acting neurotoxin and cardiotoxin that can cause tingling, numbness, abdominal pain, vomiting, weakness, irregular heart rate, and death very quickly after ingestion. Every part of monkshood plants should be considered deadly.

English Yew

The English Yew (Taxus baccata) is an attractive evergreen tree commonly used for ornamental landscaping, hedges and topiaries. However, the leaves and seeds of this tree contain poisonous alkaloids called taxanes that are toxic to humans. All parts of the tree except the fleshy red arils surrounding the seeds are poisonous. Symptoms include dizziness, dilated pupils, weakness, and difficulty breathing. The seeds within the berries also contain cyanogenic glycosides. Eating yew foliage can be fatal.


There are many varieties of nightshade plants, both wild and cultivated, that contain toxic alkaloids in the stems, leaves, unripened berries and roots. These include deadly nightshade, woody nightshade, black nightshade and bittersweet nightshade. The berries when ripe are generally less toxic, but all other parts can cause digestive distress, neurological symptoms like confusion and seizures, breathing problems and possibly death, especially in children. Avoid ingesting any part of these plants.


Hellebore plants contain cardenolides that can be toxic to humans and animals. All parts of the hellebore plant are poisonous, including the roots, stems, leaves and flowers. Hellebore poisoning causes burning of the mouth and throat, nausea, vomiting, diarrhea, dizziness, bradycardia, hypotension and breathing difficulties. Without medical treatment, hellebore ingestion can potentially lead to death via cardiac arrest. These plants should not be kept in homes with kids and pets due to the risk of accidental poisoning.

Autumn Crocus

Autumn crocus (Colchicum autumnale), also called meadow saffron, blooms in the fall with purple flowers reminiscent of crocuses. However, the bulbs and flowers of this plant contain toxic alkaloids called colchicines that can lead to serious poisoning symptoms. It causes intense burning in the mouth and throat, vomiting, diarrhea, bleeding ulcers, kidney and liver damage, respiratory paralysis, multi-organ failure and bone marrow depression. Ingesting any part of the autumn crocus can be fatal.


Pokeweed (Phytolacca americana) is a wild plant with large leaves, clusters of small berries and a thick taproot. While the cooked shoots are eaten as a spring vegetable in some cultures, the raw leaves, shoots, roots and berries contain triterpene saponins and alkaloids that can be quite toxic. Pokeweed causes severe vomiting and diarrhea which can lead to dehydration and dangerous electrolyte abnormalities. The toxins can also cause liver damage and abnormal heart rhythms. Never eat uncooked pokeweed parts.

This covers some of the most common toxic plants that should be avoided or handled very carefully when gardening or around children and pets. Being able to identify these poisonous plants can help prevent accidental ingestion and serious health problems. When in doubt about a plant, it is best to avoid contact altogether and educate children to not put unknown vegetation in their mouths. Learn to recognize toxic plants in your area and remove any growing around kids’ play areas. Seek immediate medical treatment if poisoning is suspected. With vigilance and plant awareness, poisonings can be prevented.

15 Common Toxic Plants FAQs

Below are some frequently asked questions about common toxic plants:

What are some of the most common symptoms of toxic plant poisoning?

Some common symptoms of poisoning from toxic plants include:

  • Burning or pain in the mouth, lips, and throat
  • Nausea and repeated vomiting
  • Abdominal cramps and diarrhea
  • Dizziness, confusion, dilated pupils
  • Irregular or slowed heart rate
  • Difficulty breathing, tremors, seizures
  • Kidney and liver damage
  • Multi-organ failure in severe cases

Seek immediate medical treatment if any of these symptoms develop after contact with an unknown plant.

Which parts of toxic plants are most dangerous?

The most poisonous parts of toxic plants can include:

  • Leaves, stems, stalks
  • Flowers and flower nectar
  • Seeds, berries, fruits
  • Bulbs and tuberous roots
  • Sap, milky residue
  • Bark and wood

As a rule, assume all parts of a toxic plant are poisonous unless you know for certain the edible portions. Never ingest any vegetation if unsure of what it is.

What makes plants toxic?

Plants become toxic due to naturally occurring substances they produce such as:

  • Alkaloids – A diverse group of chemicals like nicotine, strychnine, caffeine
  • Glycosides – Cause irregular heart rhythm, digestive issues
  • Toxalbumins – Proteins that inhibit protein synthesis
  • Oxalates – Affect kidneys, digestive system
  • Tannins – Interfere with digestion proteins
  • Cyanogenic glycosides – Release cyanide compound

These toxins help protect the plants but make them poisonous to humans and animals if ingested.

Can you die or suffer permanent damage from toxic plants?

Yes, ingesting extremely toxic plants like water hemlock, poison hemlock, and castor beans can cause death in humans rather quickly without treatment. Others like foxglove can cause lasting heart damage or neurological deficits. Toxic plants should always be treated as medical emergencies requiring rapid treatment.

What should you do if you think someone has been poisoned?

If poisoning from a toxic plant is suspected, immediately call 911 or your local emergency number. Do not wait for symptoms to worsen. Try to identify the plant ingested. Save any disgorged plant matter. Basic life support may be necessary. Urgent medical assessment and treatment is required for poisonings involving toxic plants to prevent permanent injury or death.

How can you make your home and garden safer regarding toxic plants?

  • Clearly identify and remove any toxic plants from your property
  • Read labels and only purchase non-toxic plants
  • Keep toxic plants fenced off or in locked planters
  • Educate children and visitors to never eat unknown plants
  • Keep poison control center numbers accessible
  • Know which parts of plants/mushrooms are unsafe
  • Supervise young kids and pets outdoors in gardens
  • Wear gloves and wash hands after handling toxic plants

Are there any look-alike toxic plants that are commonly mistaken?

Yes, some examples of toxic plants often confused for edible ones include:

  • Poison hemlock and wild carrot/Queen Anne’s lace
  • Water hemlock and parsnips
  • Foxglove and comfrey
  • Autumn crocus and crocus
  • Castor beans and edamame beans
  • Jimsonweed and tomato plant

When foraging, always positively identify any plant before ingesting. If unsure, do not eat it.


In summary, many common backyard and garden plants have the potential to cause toxicity in humans and animals. Being able to identify toxic vegetation is an important safety skill, especially for those with small children or pets. If ingested, toxic plants can result in a wide range of concerning symptoms and even be fatal. Seeking prompt medical treatment is essential. Avoidance, removal, and supervision around poisonous plants can help prevent accidental exposures. Education and awareness about plant toxicity allows us to safely enjoy the beauty of nature while keeping our families safe.