15 Poisonous Flowers and Plants to Avoid

By Amanda Lutz | January 26, 2024

Close up on blooming purple Rhododendron in springtime.

Flowers and plants can delight the senses, adding beauty and fragrance to our homes and bringing biodiversity to our gardens. While our favorite plants can be visually stunning, they could also be harmful to our loved ones and pets. Many common flowers and plants are poisonous, causing anything from minor skin irritations to potentially severe allergic reactions.

Read on to learn about 15 of the most common poisonous flowers and plants, as well as how to spot them; what symptoms to watch out for; and how to protect yourself, your loved ones, and your pets.

Toxicity Levels

Flowers and plants have four types of toxicity levels.

Some plants can have multiple toxicity levels. For example, an African lily has both Level 2 and Level 4 toxicity, meaning it is a minor toxin and may cause dermatitis. Understanding the toxicity levels of plants and flowers can help you watch for symptoms and know when to contact a doctor.

Poisonous Flowers and Plants

Identifying toxic plants that may be present in your backyard, your home, or in nature will help you avoid touching or consuming these potentially dangerous flowers, vines, shrubs, and plants.

1. Azalea

Poisonous to: People, but more deadly for pets 

Toxicity level: Major toxicity (Level 1)

Symptoms: Low blood pressure, irregular heartbeat, seizures

Parts to avoid: Leaves, flowers, pollen, and nectar

Relatives of the rhododendron family, the azalea is a flowering shrub commonly found in gardens because of its spectacular blooms. Look for ruffly, multipetaled flowers with five or fewer stamens, which are the long, skinny part that sticks out of the middle of the flower. 

2. Castor Bean

Poisonous to: People and pets

Toxicity level: Major toxicity (Level 1)

Symptoms: Nausea, vomiting, severe dehydration, kidney and liver problems 

Parts to avoid: Beans

While the castor bean is used to make caster oil, it also contains ricin, one of the deadliest known toxins. The plant is often grown as an ornamental plant in gardens. Look for reddish-green leaves with multiple points and inch-long bean pods. 

3. Daffodil

Poisonous to: People and pets 

Toxicity level: Minor toxicity (Level 2), Dermatitis (Level 4)

Symptoms: Nausea, vomiting, intestinal distress, abdominal pain

Parts to avoid: While the whole plant contains some toxins, the highest concentrate can be found in the bulb

You’ll find the cheery yellow daffodil featuring as a garden plant in yards and planters or even on roadsides in the spring. This is the season when the bulbs produce bright yellow flowers with a distinctive trumpet shape. 

4. Deadly Nightshade

Poisonous to: People and pets

Toxicity level: Major toxicity (Level 1)

Symptoms: Blurred vision, headache, hallucinations, convulsions 

Parts to avoid: All parts of the plant contain toxins, but the berries are the most deadly

Deadly nightshade is one of the most toxic plants in North America, but thankfully, it’s relatively easy to spot. Look for bell-shaped dark purple flowers and round black berries. 

5. Foxglove

Poisonous to: People and pets

Toxicity level: Major toxicity (Level 1)

Symptoms: Irregular heart rate, confusion, headache, lethargy or drowsiness, low blood pressure

Parts to avoid: Flowers, stems, leaves, and seeds

A member of the Digitalis family, the foxglove is easy to spot thanks to its distinctive bell-shaped flowers. Usually pinkish-purple in color, you’ll find these flowers in woodlands, gardens, and roadsides in colors ranging from white to deep purple.

6. Jimson Weed

Poisonous to: People, pets, and livestock 

Toxicity level: Major toxicity (Level 1)

Symptoms: Heart palpitations, breathing difficulties, hallucinations, death

Parts to avoid: Whole plant

Also known as the devil’s snare, this deadly plant is an invasive species found throughout the Northern Hemisphere. Jimson weed mimics the morning glory, with white or purple trumpet-shaped flowers, but also produces a spiny fruit nicknamed a thorn apple. 

7. Lantana

Poisonous to: People and pets

Toxicity level: Major toxicity (Level 1)

Symptoms: Vomiting, diarrhea, weakness, depression

Parts to avoid: Leaves and berries

You can find this invasive plant species worldwide, but it’s also commonly used in gardens as an ornamental plant. Look for broad leaves with serrated edges and clusters of small, multicolored flowers at the top of the stems. 

8. Lily of the Valley

Poisonous to: People and pets 

Toxicity level: Major toxicity (Level 1), Dermatitis (Level 4)

Symptoms: Fainting, irregular or slow heartbeat, intestinal distress, confusion

Parts to avoid: All parts of the plant

Lily of the valley is not only a common garden plant but is also often used in floral arrangements. Look for the distinctive tiny white flowers shaped like bells and the dark green, rounded, glossy leaves. You can also spot this flower by its strong, sweet fragrance.

9. Oleander

Poisonous to: People and pets

Toxicity level: Major toxicity (Level 1), Dermatitis (Level 4)

Symptoms: Blurred vision, stomach pain, nausea, vomiting, heart arrhythmia 

Parts to avoid: Whole plant

Oleander is a popular plant used for hedges because it grows quickly and produces gorgeous flowers. However, it’s highly toxic, especially the Nerium oleander variety, and consuming any part of the plant can be deadly. Look for silvery-green, spiky leaves and five-petaled pink, red, or white flowers. 

10. Poinsettia

Poisonous to: Everyone, but especially children and pets

Toxicity level: Minor toxicity (Level 2), Dermatitis (Level 4)

Symptoms: Mild skin irritation, nausea, and diarrhea 

Parts to avoid: Sap-containing stems and leaves

Poinsettias are a favorite Christmas decoration despite their mild toxicity. Their bold red or white pointed leaflike “bracts” make them a popular choice for complementing holiday decor, and the plants can serve as an excellent centerpiece for your table. While rarely (if ever) fatal, the plant can cause mild skin irritation and could cause intestinal issues if eaten. 

11. Poison Hemlock

Poisonous to: People and pets 

Toxicity level: Major toxicity (Level 1)

Symptoms: Confusion, high blood pressure, muscle weakness, rapid heartbeat, tremors, vomiting

Parts to avoid: Whole plant

You can find poison hemlock across the North American landscape, growing in ditches, riverbanks, and fields. You’ll know it by the tiny, white flowers that grow in umbrella-like clumps along with its ferny leaves and unpleasant smell. 

12. Poison Ivy

Poisonous to: People and pets 

Toxicity level: Minor toxicity (Level 2), Dermatitis (Level 4)

Symptoms: Skin rashes, itchy skin, skin blisters

Parts to avoid: Leaves, stems, and roots

The best way to identify poison ivy is to remember the saying, “Leaves of three, let it be.” This refers to how the leaves grow in groups of three at the end of thin stems. You’ll commonly find poison ivy in woodland areas, but it can grow elsewhere, including around your home. If you spot it growing near your house, you’ll want to clear it right away.

13. Poison Oak

Poisonous to: People, and less commonly pets

Toxicity level: Dermatitis (Level 4)

Symptoms: Skin irritation, including itching, rashes, and blistering 

Parts to avoid: Primarily the leaves

Poison oak is another plant included in the “leaves of three, let it be” rule. Look for leaves growing in clusters of three, along with small, light green or yellow flowers and berries. Poison oak grows in various conditions, primarily in the West and Southeastern United States. 

14. Rhododendron

Poisonous to: People and pets

Toxicity level: Major toxicity (Level 1)

Symptoms: Nausea, diarrhea, breathing difficulties, irregular heartbeat, death

Parts to avoid: All parts of the plant

It’s easy to spot a rhododendron because of its distinct flowers and because it’s widely used as a decorative plant in parks and gardens. Look for large, flowering bushes with evergreen leaves. When blooming, the bell-shaped flowers clump at the end of the stem. The flowers may be shades of pink, white, purple, or yellow. 

15. Water Hemlock

Poisonous to: People and pets

Toxicity level: Major toxicity (Level 1)

Symptoms: Seizures, cardiac arrest 

Parts to avoid: Whole plant

A member of the carrot family, this plant is known as one of the deadliest in North America. Water hemlock grows in damp, boggy areas like marshes and ponds. Look for the tiny white flowers growing in umbrella-like clumps.

What Should You Do If You’re Exposed to a Poisonous Flower?

If you touch a poisonous plant, thoroughly wash the skin that came in contact with the plant using mild soap and warm water. Topical treatments can help relieve burning and blistering, and taking an over-the-counter antihistamine might help ease symptoms such as itching.

Ingestion of a suspected poisonous plant in small or large amounts should be taken very seriously. If you believe that you, a loved one, or a pet has eaten a poisonous flower, you should immediately seek medical attention. Go to the nearest emergency room or contact Poison Control. The Poison Control hotline is available 24 hours a day, 365 days a year.

Our Recommendation

It’s a good idea to familiarize yourself with some of the most common poisonous plants and flowers growing in your area, whether you’re starting a garden or simply love enjoying the great outdoors. Many poisonous plants are easily mistaken for safe varieties, and you don’t want a misidentification to lead to illness.
To keep yourself safe, wear gloves when handling plants, especially if you’re unsure of their type. Ensure that young children and pets don’t chew on houseplants or plants growing outdoors, and prevent them from eating unfamiliar seeds or berries.

Poisonous Flowers to Avoid FAQ

What’s the world’s most poisonous flower?

The Nerium oleander is the world’s most poisonous flower. Eating just a little bit of this beautiful bloom can lead to death, and even inhaling the smoke from a burning Nerium oleander can make you ill.

What common plants are poisonous?

Common poisonous plants include lily of the valley, daffodils, azaleas, rhododendrons, foxglove, and oleander. These plants are often prized for beautiful flowers but should be handled carefully and never ingested.

What flower is poisonous to touch?

Flowers that are poisonous to touch include hogweed, poison ivy, and poison oak. The sap inside the plant often causes the symptoms of poisoning, which might include skin irritation, confusion, low blood pressure, and even organ failure.