Numerous common houseplants pose a toxic risk to humans and animals if ingested. Care should be taken when cultivating known poisonous houseplants to keep them out of the reach of children and pets. It is estimated that more then 700 plant species in both the United State and Canada have caused death or severe illness in humans, according to the University of Maine. Young children are especially at risk of accidental ingestion when exposed to indoor poisonous houseplants.
Dumbcane (Dieffenbachia sp)
The dumbcane (Dieffenbachia sp.), a popular houseplant known to help purify the air, contains the toxin calcium oxalate. When ingested by mouth, tongue and throat quickly swell with intense burning sensations. The airway can quickly become blocked from the fast, extreme swelling, which results in death from asphyxiation. After exposure the suffer may suffer a speech impediment for up to a week
Exposing the eyes to the plant's sap can cause irritation, swelling, burning and excessive tearing.
Heart Leaf Philodendron (Philodendron sp.)
Heart leaf philodendrons (Philodendron sp.) contain oxalates, which quickly irritate the delicate tissue of the mouth and throat when ingested. Swelling of the tissue quickly occurs when can cut off the air supply of the sufferer and result in asphyxiation.
The plant's sap causes dermatitis when it comes into contact with skin. The skin will appear red and swollen with minor itching occurring.
Cyclamen (Cyclamen persicum)
The cyclamen (Cyclamen persicum) grows from a bulb, which is highly toxic if ingested. The plant contains a substance known as Terpenoid saponins that has a purgative reaction. The plant and bulbs contain an unpleasant flavor for both humans and children so ingestion occurrences is quite rare.
Cats have been known to chew on the plant, which causes the animal to suffer severe salivation, vomiting and diarrhea. The symptoms often progress to seizure and deadly heart rhythm abnormalities.
English Ivy (Hedera helix)
English ivy (Hedera helix) contains didehydrofalcarinol, falcarinol and hederasaponins toxins. When ingested, the plant causes vomiting, nervous conditions and diarrhea to occur.
A few individuals or animals suffer dermatitis when their skin comes into contact with the foliage, sap or berries of the vine. The dermatitis causes itching, redness and severe blistering to occur on the skin.
Birds widely consume the berries of the Ivy plant with only a laxative reaction. The berries are bitter and unpalatable to both humans and mammals.