Oxalate Poisoning

Updated: Oct 12, 2019
  • Author: Jason F Kearney, MD, MBA; Chief Editor: Sage W Wiener, MD  more...
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Practice Essentials

Plant exposures are some of the most frequent poisonings reported to poison control centers. Exposures to plants containing oxalate crystals, such as Philodendron and Dieffenbachia, are among the most common toxic plant exposures reported in the US.

For the past 200 years, the irritant properties of the Dieffenbachia plant have had various uses, including punishing slaves and treating gout, impotence, and frigidity. Today, plants containing oxalate are admired for their ornamental beauty and found in public places and homes.

The following plants contain oxalates:

  • Anthurium ( Anthurium species) [1]
  • Arum, Araceae ( Arisaema species)
  • Caladium ( Caladium bicolor)
  • Calla lily ( Zantedeschia species)
  • Chinese evergreen ( Aglaonema species)
  • Dieffenbachia ( Dieffenbachia species) (see the image below) [2]
  • Dieffenbachia Dieffenbachia
  • Jack-in-the pulpit ( Arisaema triphyllum) (see the image below)
  • Jack-in-the-Pulpit Jack-in-the-Pulpit
  • Monstera, Ceriman ( Monstera deliciosa)
  • Nephthytis ( Syngonium podophyllum)
  • Philodendron ( Philodendron species)
  • Pothos or Hunter's robe ( Epipremnum aureum)
  • Skunk cabbage ( Symplocarpus foetidus) (see the images below)
  • Skunk Cabbage Skunk Cabbage
    Skunk Cabbage Skunk Cabbage


Nonsoluble calcium oxalate crystals are found in plant stems, roots, and leaves. The stalk of the Dieffenbachia plant produces the most severe reactions. These needlelike crystals produce pain and edema when they contact lips, tongue, oral mucosa, conjunctiva, or skin. [3] Edema primarily is due to direct trauma from the needlelike crystals and, to a lesser extent, by other plant toxins (eg, bradykinins, enzymes). [4, 5]



Philodendron and Dieffenbachia exposures are among the most common plant exposures reported to poison control centers. According to the 2017 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS), 4844 single exposures were documented for oxalate plant poisonings. [6]

The majority of oxalate plant exposures occur in children younger than 5 years while sampling houseplants in the home. The 2017 Annual Report of the American Association of Poison Control Centers' NPDS reported 3557 oxalate plant exposures in those younger than 6 years, 709 exposures in those aged 6-19 years, and 467 exposures in those older than 19 years. [6]



Most patients who have been exposed to plants containing oxalates completely recover. In most cases, nonsoluble oxalate plants produce self-limited symptoms and clinical manifestations. Significant morbidity or mortality is extremely rare.

There are some case reports of severe injuries that caused oro-pharyngeal inflammation and edema, with impending obstruction of the upper airways. One case report of an infant fatality attributed to airway obstruction after exposure to Dieffenbachia exists. [7]   

The 2017  Annual Report of the American Association of Poison Control Centers' NPDS reported 960 minor outcomes, 46 moderate outcomes, no major outcomes, and no deaths from oxalate plant exposures. [6]