Twelve Poisonous House Plants and Their Health Effects
Benefits of Indoor Plants
Indoor plants are a wonderful addition to a home and have many benefits. They are lovely to see and often improve the appearance of the home. Plants such as herbs are edible and may be medicinal as well. Some plants absorb air pollutants and help to purify indoor air. Learning how to take care of house plants teaches children responsibility and may arouse their interest in gardening, which can be a lifelong joy. Having plants in a home is also a great way to connect with nature.
Although it's enjoyable to grow plants indoors, it's important that everyone in the family knows about any dangers associated with them. While many house plants are safe, some are poisonous for people and/or pets. This may not be a problem in a home containing only adults or only adults and older children. If young children or pets live in the home, though, it's a good idea to avoid dangerous plants.
It may be tempting to bring a beautiful but mildly toxic plant into a home and keep it out of reach of children or pets. In this is done, it's important to watch out for dropped leaves and dangling vines, tendrils, and aerial roots, which can bring the plant into contact with children and animals.
Effects of Plant Poisons
Any plant that's classified as poisonous needs to be treated with care, even if it's only mildly toxic. The health effects of a plant toxin depend on many factors, including:
- the nature of the toxin
- the part of the plant that's eaten
- how much toxin is in the plant
- how much of the plant is ingested
- the length of time that the person is exposed to the toxin
- the body mass of the person who has eaten the plant
- the overall health of the person at the time of ingestion
- the individual sensitivity of the person to the toxin
Dieffenbachia or Dumb Cane
Dieffenbachia is a tropical plant that is native to Central and South America. It's popular as a house plant because of its large and attractive leaves. The leaves are green with light yellow or cream blotches arranged in a variety of patterns. The stems are thick and resemble canes.
Dieffenbachia is a relative of the North American skunk cabbages and belongs to the family Araceae. As in a skunk cabbage, Dieffenbachia's small flowers are born on a long, rod-like structure called a spadix, which is partly enclosed by a sheath called a spathe. This type of inflorescence (cluster of flowers) is characteristic of the Araceae.
"Dieffenbachia" is both the genus of the plant and one of its common names. The genus is the first part of the scientific name of an organism and the species is the second part. For example, Dieffenbachia bomannii is the scientific name of a popular house plant. Dieffenbachia is the plant's genus and bowmannii is the species.
Dieffenbachia was given its alternate name of dumb cane because the plant can literally strike someone dumb if they eat it.
Types of Dieffenbachia
Raphides and Symptoms of Dieffenbachia Poisoning
All parts of a Dieffenbachia plant contain needle-shaped crystals of calcium oxalate called raphides. Raphides occur in other plants as well and are thought to protect the plants from attack by herbivores. Researchers believe that Dieffenbachia contains other toxins in addition to calcium oxalate.
Raphides can be very irritating to human lips as well as the mouth, tongue, and digestive tract. When the raphides irritate the mouth parts they may cause them to become inflamed and swell. The swelling may temporarily prevent speech (hence the name "dumb cane") or, more seriously, block the airway and interfere with breathing. Raphides in the eye can be especially painful and can damage the cornea, which is the outer layer of the eye.
Raphides are harmful in another way. By wounding the lining of the mouth and digestive tract, they enable other toxins to enter the body through the damaged area. These toxins might otherwise pass through the body and either be unabsorbed or be broken down into less harmful substances in the digestive tract.
Usually, the damage done by Dieffenbachia is unpleasant but not serious. The discomfort in the mouth may be severe and last for days, however. Fatalities have occurred from Dieffenbachia poisoning, but they are very rare.
A Large Dieffenbachia Plant
Dieffenbachia can produce additional symptoms. The skin may develop a rash and an itch after exposure to the plant's sap. It's therefore a good idea to wear gloves when handling the plant. Ingestion of the plant may cause nausea, vomiting, and diarrhea.
Treatment of Dieffenbachia Poisoning
According to the NIH (National Institutes of Health), if someone has chewed or eaten Dieffenbachia their mouth should be washed out with a cold, wet cloth. They should also be given milk to drink and a poison control center should be contacted. If someone is unconscious or unable to swallow they must never be given anything by mouth, however. The hands and eyes of the injured person must be washed if these body parts have contacted the poison.
Caladium, Philodendron and Pothos
Like Dieffenbachia, Caladium, Philodendron, and Pothos belong to the family Araceae and are generally chosen as house plants for their large and attractive leaves. Also like Dieffenbachia, they contain calcium oxalate and can produce similar symptoms when they're ingested. Treatment for the poisoning is the same as the treatment for Dieffenbachia poisoning.
Types of Caladiums
Caladium is both a genus of plants and a common name for the plants in the genus. Many different varieties of caladiums exist and many different leaf patterns are available. The arrow-shaped leaves are generally variegated (having more than one color) and contain different pigments, which may be green, yellow, pink, red, or brown in color.
Caladiums can be grown in a container indoors or outdoors and also grow well in a garden. The leaves are beautiful and may become very large. A caladium is sometimes called "elephant ear", a name that is applied to other plants as well. Another interesting and beautiful name for the plant is "angel wings".
Although Caladium is toxic due to the presence of calcium oxalate and another unidentified compound, in general a large amount of the plant needs to be eaten before symptoms appear.
There are many different species in the genus Philodendron and many of these are kept as indoor plants. Philodendrons have a wide variety of interesting leaf shapes and color patterns. They can be so different from one another that it's sometimes hard to believe that they belong to the same genus. Many philodendrons are climbers and produce aerial roots, while others don't climb.
The evidence suggests that Philodendron is only mildly poisonous and that most people have to eat a large quantity of the plant before they develop symptoms.
Pothos (Devil's Ivy)
Pothos (genus Epipremnum) is another popular house plant. It's an evergreen vine which trails over the edge of its container. The plant is attractive and doesn't require much attention, which is why it's popular in public areas such as shopping centers and offices.
Pothos comes in various species and varieties, some with solid green leaves and some with variegated leaves. The leaves are usually heart-shaped with pointed tips.
Pothos and some types of philodendrons are often confused with one other. If someone wants to make sure that they are buying a pothos instead of a philodendron, or the other way round, they should visit a plant nursery or garden store which has knowledgeable and experienced staff. Confusing the two plants in a store won't be important with respect to toxicity, however. Like philodendrons, pothos are classified as only mildly poisonous.
Devil's ivy was once classified in the genus Pothos instead of the genus Epipremnum, which accounts for its most popular common name.
Peace Lily or Spathe
Like the plants above, the peace lily or spathe (genus Spathiphyllum) belongs to the family Araceae. It isn't a true lily, despite its name.
The leaves of the peace lily are long, narrow, and leathery and have a pointed tip. They are dark green in color and have a shiny surface and prominent veins.
The inflorescence has a white or light green spathe and is borne on a stalk that extends above the rest of the plant. The peace lily got its name because the white spathes look like flags of surrender or peace.
Like its relatives above, the peace lily contains calcium oxalate and can produce unpleasant symptoms if it's taken into the mouth or if liquid from the plant contacts the skin. Generally, though, the plant isn't harmful unless it's chewed or eaten in large amounts.
The calla lily (Zantedeschia aethiopica) is native to Southern Africa. Like the peace lily, the calla lily isn't a true lily (family Liliaceae) but is a member of the family Araceae.
The large and beautiful white "petal" of the calla lily is actually a spathe. It surrounds a yellow spadix, which bears the small flowers. The spathe is gracefully curved and has an elegant and unusual shape. Calla lilies with yellow and pink spathes are available.
The calla lily is yet another plant that contains calcium oxalate raphides. It's only mildly poisonous, which is good news for people who would like to bring this beautiful plant into their home. As always, though, the raphides can be irritating and the effect of the toxin depends on the amount that is ingested.
Oleander, or Nerium oleander, is beautiful but extremely toxic, even in small amounts. It's an evergreen flowering shrub that is grown both outdoors and indoors. The flowers are pink, red, purple, or white. The leathery leaves are long and narrow and have a pointed tip. They are arranged in pairs or whorls on the stem.
Known toxins in oleander include oleandrin, oleondroside, neriin, and digitoxigenin. The toxins are present in all parts of the plant. Even the flower nectar of Oleander and the honey that bees make from the nectar contain a dangerous amount of poison.
Oleander in a Garden
The list of symptoms caused by oleander ingestion is long. It can be broken down into categories based on the part of the body that the toxins affect. Not all of the symptoms may appear and they may be caused by a different problem. It the affected person had access to an oleander plant, however, the condition could be very serious.
- stomach pain
- blurred vision
- the appearance of halos in the visual field
- a rash
- a slow or irregular heartbeat
- low blood pressure
Nervous System Problems
- loss of consciousness
Oleander poisoning is a medical emergency. Treatment by a medical professional is essential.
The most dangerous part of some popular flowering plants that develop from bulbs is the bulb itself, since the plant toxins are concentrated in the bulb. Other parts of the plant also contain the toxins, however.
Daffodils and Narcissus
Daffodil bulbs contain calcium oxalate crystals and a toxic alkaloid called lycorine. Eating bulb tissue can cause mouth and throat irritation, stomach upset, nausea, vomiting, and diarrhea. In addition, people who handle daffodil bulbs may develop dermatitis. This is a condition in which the skin becomes inflamed, red, and itchy.
Daffodil bulbs are sometimes mistaken for edible bulbs, such as onions. An instance of this mistaken identity occurred in an English elementary school in 2009. Onion bulbs were collected from a school garden to add to soup that the children were making. Somehow a daffodil bulb became mixed with the onion bulbs. Twelve children developed stomach cramps and vomiting after eating the soup and were taken to hospital. They all recovered, however.
Daffodils belong to the genus Narcissus. Other members of this genus are also sold as house plants and can cause the same health problems.
More Plants with Poisonous Bulbs
Like daffodils, hyacinths contain calcium oxalate and lycorine. Once again the toxin is most concentrated in the bulbs of the plant. Eating hyacinth bulbs produces the same symptoms as eating daffodil bulbs.
Tulip bulbs contain a toxin called tuliposide A. This can cause dermatitis in humans, but apparently only in people who are sensitive to the toxin. People who frequently handle the bulbs are most susceptible to the dermatitis. Tulips also contain calcium oxalate. Eating tulip bulbs may cause nausea and diarrhea.
English ivy (Hedera helix) is a climbing and trailing vine. Cultivated ivy is sold with both solid green leaves and variegated leaves. Leaves on the climbing stems have pointed lobes. The leaves on flowering stems are oval. English ivy is an attractive plant, but in the wild it can become invasive.
The liquid from a damaged ivy plant can severely irritate the skin and cause dermatitis. After handling ivy, a person may find that their skin is itching, red, and blistered.
Ivy can also cause very serious internal problems, although generally many leaves must be eaten to cause these effects. A person may develop a fever and experience breathing difficulties, vomiting, delirium, hallucinations, and convulsions.
Lily Poisoning in Cats
In this article I've described the toxicity of plants in relation to humans. The effects of plant chemicals on pets such as cats and dogs are sometimes similar to the effects on humans. This isn't always the case, however, so pet owners should do some diligent research before they bring a plant into their home.
An example of the different effects of a plant poison in humans and pets is a toxin that's present in lilies. True lilies are often deadly for cats but aren't for humans. An unidentified chemical in the plant causes kidney damage in cats, which is frequently fatal.
It's very important that vet treatment is sought soon after a cat eats any part of a lily. The longer the time between ingestion and treatment, the less likely that the cat will survive. Signs of lily ingestion can also be signs of other illnesses. If a cat has had access to lilies, however, lily poisoning must always be considered as a cause of the symptoms. There is no time to lose before starting treatment, so it's important to get to a vet quickly.
Not all plants with lily in their name are true lilies (genus Lilium). The scientific name is important when considering whether a "lily" is toxic.
Symptoms of Lily Poisoning in Cats
Symptoms of lily poisoning include:
- loss of appetite
All pet owners should know where their nearest animal emergency clinic is located as well as the hours when the clinic is open. They should also think about their transport method to the clinic. Public transit is rarely suitable in an emergency.
Preventing lily poisoning is much easier than treating it. Lilies in indoor pots, cut lilies in bunches of flowers and bouquets, and even lily pollen that has fallen on other flowers in a bunch must all be avoided.
Someone with a cat in the family should never bring lilies into the home, even if the cat has shown no tendency to eat house plants. The risk is too great.
Safe House Plants
I love my pets and also enjoy having house plants in my home. I would never buy plants that could harm my dogs or cats, but even so I have a nice collection of indoor plants. Someone with young children or pets can still enjoy the presence of house plants. They should do some research before they buy a plant to check that it is non-toxic for everyone in the family, however.
References and Resources
- In the United States, the National Capital Poison Center offers a free phone number that people can call for help with a potential poisoning case. Help is provided 24 hours a day and 7 days a week. When symptoms are serious, however, it may be more important to get to a hospital than to phone a poison control center.
- The U.S. National Library of Medicine (run by the NIH) has information about Dieffenbachia poisoning.
- The National Library of Medicine also describes oleander poisoning.
- The National Capital Poison Center describes the dangers of daffodils.
- A BBC news report describes the incident in which a daffodil bulb was mistakenly added to soup.
- ASPCA (the American Society for the Prevention of Cruelty to Animals) has a useful website with lots of information about poisoning in pets. They have an emergency phone number that is available 24 hours a day and 365 days a year, but they say that a $65 fee "may be applied" to the caller's credit card.
- ASPCA provides a list of toxic and non-toxic plants for dogs, cats, and horses. The list includes information about lilies and cats.
Questions & Answers
What are some indoor plants that are not poisonous?
I’ve chosen to list some plants that are non-toxic to humans, dogs, and cats. It should be noted that even non-toxic plants can be irritating to the digestive tract if eaten in large amounts, however. In addition, some humans and animals have a sensitivity to the effects of a particular plant that other individuals lack. I use the ASPCA website (American Society for the Prevention of Cruelty to Animals) as my main source for determining whether a plant is safe for dogs and cats.
The African violet (Saintpaulia) is one of my favorite houseplants because it’s so pretty and it’s non-toxic for my pets. I love Christmas cactus (Schlumbergera) for the same reason. The cactus is also easy to care for. Other non-toxic plants that I haven’t kept in my home include the Boston fern (Nephrolepis exaltata), Peperomia, the prayer plant or maranta (various scientific names), and the lipstick plant (Aeschynanthus).
© 2013 Linda Crampton