Poisonous House Plants

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 House plants have become an attractive and important part of home and office decor. In addition to adding both color and beauty to the home, they may also present a hazard, especially if there are young children in the home.

A poisonous plant is one that contains a chemical substance which produces a harmful reaction in the body of humans or animals when taken in small or moderate amounts. A harmful reaction could include allergic reactions, dermatitis or skin irritation, or internal poisoning. Allergic reactions are not always classified as poisoning and will not be treated as such here. This is because there is a wide range of plants that can cause allergic reactions, and sensitivity to a particular plant varies among individuals. There is also a range of tolerance among individuals to the toxins that cause dermatitis or internal poisoning. Not every person will react the same way when in contact with a poisoning agent.

We should all be aware of the potential problem that exists with certain house plants which have toxic properties. This does not imply that you should rid your of all of these plants but that you should realize some plants pose a potential danger. Often, large quantities of a plant classified as poisonous must be ingested before harmful effects occur.

It is your responsibility to know the identity and scientific name of the plants in your home that are potential hazards. Children should be taught at an early age to keep unknown plants and plant parts out of their mouths. They too should be made aware of the danger of poisonous plants.

If any of the house plants listed in this publication are ingested and poisoning is suspected, phone your family doctor or nearest hospital emergency room immediately. Give all pertinent information to the doctor, including the name of the plant (preferably the scientific name), the toxic agent, the quantity eaten and the symptoms.

Toxic Agent
Type of Poisoning
Poisonous Part
(Rhododendron occidentale)
Andromedotoxin, arbutin glucoside
Internal poisoning
All partsNausea, salivation, vomiting, weakness, dizziness, difficulty in breathing, loss of balance. 100 to 225 grams of azalea leaves must be eaten to seriously poison a 55 lb (25 kg) child.
Bird of Paradise
(Strelitzia reginae)
Internal poisoning3-angled capsule and seedsVomiting, diarrhea, dizziness and drowsiness.
(Caladium hortulanum)
Calcium oxalate and asparagine
Internal poisoning
All partsIngestion can cause severe irritation to the mouth and throat, may also be an irritant to stomach and intestines.
Calla Lily
(Zantedeschia aethiopica)
Calcium oxalate
Internal poisoning
Leaves and rhizome Ingestion can cause burning and swelling of the mouth and throat. Vomiting.
Castor Bean
(Ricinus communis)
Internal poisoning
Seeds and to a lesser extent leavesBurning of the mouth and throat, nausea, vomiting, severe stomach pains, diarrhea, excessive thirst, prostration, dullness of vision, convulsions, uremia and death. 1 - 3 seeds may be fatal to a child.
Crown of Thorns
(Euphorbia milii splendens)
Unknown irritant in sap Dermatitis and
Internal poisoning
SapContact causes skin and eye irritation, ingestion of sap causes swelling of the tongue, mouth, and throat, vomiting.
(Cyclamen persicum)
Internal poisoning
BulbIntense stomach cramps, vomiting and diarrhea.
(Sedum morganianum)
Unidentified glucosidesAll partsVomiting, diarrhea, weakness, respiratory depression.
(Dieffenbachia sp.)
Calcium oxalate and asparagine
Internal poisoning
All partsBiting or chewing rapidly produces irritation and burning of the surface of mouth, tongue and lips. The swelling may immobilize the tongue, interfere with swallowing and breathing and in severe cases cause choking. Symptoms can last for days.
Elephant Ear
(Colocasia spp.)
Calcium oxalate Asparagine
Internal poisoning
All partsBurning of the mouth and throat with swelling, salivation, vomiting and diarrhea.
English Ivy
(Hedera helix)
Saponic glycosine Hederagenin
Internal poisoning
LeavesExcitement, difficult breathing and coma.
Flamingo Flower
(Anthurium spp.)
Calcium oxalate and asparagine
Internal poisoning
All partsIngestion can cause severe irritation to the mouth and throat, may also irritate stomach and intestines.
(Hyacinth orientalis)
Internal poisoning
BulbIntense stomach cramps, vomiting and diarrhea.
(Hydrangea macrophylla)
Hydragin-cyanogenic glycoside
Internal poisoning
Leaves and budsVomiting, diarrhea, gasping and rapid breathing.
Jerusalem Cherry
(Solanum pseudocapsicum)
Solanine alkaloids
Internal poisoning
All parts - highest concentrations in the unripened fruit and leaves Stomach pains, paralysis, low temperature, dilated pupils, vomiting, diarrhea, circulatory and respiratory depression, loss of sensation and death.
(Lantana spp.)
Lantanin alkaloid
or lantadene A
Internal poisoning
Green berriesStomach and intestinal irritation, muscular weakness, circulatory collapse and death. Acute symptoms resemble atropine poisoning.
Milk bush
(Euphorbia trigona)
Unknown irritant in sap Dermatitis &
Internal poisoning
SapSkin and eye irritation, swelling of tongue, mouth and throat, vomiting.
(Narcissus spp.)
Internal Poisoning
BulbNausea, vomiting, diarrhea, trembling, convulsions. May be fatal.
(Nerium oleander)
Oleandrin, nereoside. Dermatitis and
Internal poisoning.
All parts - Green or dryExtremely toxic - a single leaf is considered potentially lethal to humans. Symptoms begin several hours after ingestion, and include dizziness and drowsiness, increased pulse rate, cold extremities, abdominal pain, nausea, weakness and vomiting.
(Philodendron spp.)
Calcium oxalate
Internal poisoning
Leaves and stemsBurning of the mouth, vomiting and diarrhea.
(Sedum acre)
Unidentified glucosidesAll partsVomiting, diarrhea, weakness, respiratory depression.
(Tulipa spp.)
TulipeneBulbVomiting, diarrhea.

If additional information is desired, there are several excellent books available on the subject of poisonous plants.
  1. Creekmore, H. Daffodils are Dangerous: The Poisonous Plants in Your Garden. Walker and Co. N.Y. 1966.
  2. Hardin, J.W. and J.M. Arena. Human Poisoning from Native and Cultivated Plants. Duke University Press. Durham, N.C. 1969.
  3. Kingsbury, J.M. Poisonous Plants of the United States and Canada. Prentice Hall, Inc. Englewood Cliffs, N.J. 1964.
  4. Kingsbury, J.M. Deadly Harvest: A Guide to Common Poisonous Plants. Holt Rinehart and Winston, N.Y. 1972.

Other Documents in the Series

  Easy-To-Grow House Plants
Poisonous House Plants - Current Document
House Plants: What to Grow
House Plants: Terrariums
House Plants: Forcing Bulbs
House Plants: Gift Plants
For more information about the content of this document, contact Shelley Barkley.
This information published to the web on July 5, 2001.
Last Reviewed/Revised on October 26, 2013.