Plant Poisoning from Oxalates

Updated: Feb 19, 2020
Author: Jason F Kearney, MD, MBA; Chief Editor: Sage W Wiener, MD 


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 United States.

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) (see the image below)
  • Caladium Caladium
  • Calla lily ( Zantedeschia species)
  • Chinese evergreen ( Aglaonema species)
  • Dieffenbachia ( Dieffenbachia species) [2]  (see the image below)
  • Dieffenbachia, commonly known as dumb cane Dieffenbachia, commonly known as dumb cane
  • Jack-in-the pulpit ( Arisaema triphyllum) (see the image below)
    Jack-in-the-Pulpit Jack-in-the-Pulpit
  • Monstera, Ceriman ( Monstera deliciosa) (see the image below)
    Monstera deliciosa Monstera deliciosa
  • Nephthytis ( Syngonium podophyllum)
  • Philodendron ( Philodendron species) (see the image below)
    Philodendron Philodendron
  • 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 2018 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS), 4509 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 2018 Annual Report of the American Association of Poison Control Centers' NPDS reported 3225 oxalate plant exposures in those younger than 6 years, 706 exposures in those aged 6-19 years, and 449 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.  However, there are case reports of severe oropharyngeal inflammation and edema, with impending obstruction of the upper airways.[7]   

The 2018 Annual Report of the American Association of Poison Control Centers' NPDS reported 878 minor outcomes, 49 moderate outcomes, no major outcomes, and no deaths from oxalate plant exposures.[6]



History and Physical Examination

Clinical manifestations, if they develop, occur rapidly and may include the following:

  • Keratoconjunctivitis and corneal abrasions after contact with plant material [8]
  • Edema, erythema, bullae, and inflammation of mouth and oral mucosa after contact; esophagitis
  • Slurred or unintelligible speech
  • Laryngeal edema (with sufficient contact)
  • Superficial necrosis developing days after initial contact
  • Local skin erythema and/or edema (typical of a contact dermatitis) due to contact with plant sap or juices [9]




Prehospital Care

Decontaminate mouth, eye, and skin by physically removing all plant material. Treat eye and skin exposure with copious water irrigation. Rescuers should protect themselves from contact with plant materials.

Emergency Department Care

Most exposures are self-limited and only require analgesics for patient comfort.

For oral exposures, physically remove any plant material in the oral cavity. Assess for any airway compromise. Individuals without airway compromise can drink cold liquids and eat crushed ice, ice cream, or frozen ice pops or desserts for relief.[7] Oral swishing with diphenhydramine elixir provides local anesthetic and antihistaminic effects. Individuals with laryngeal edema may be treated with antihistamines and observed and/or admitted until edema improves. No clinical data support use of steroids in laryngeal edema induced by oxalate-containing plants.

Treat eye exposures with copious water irrigation. Employ slit lamp examination and fluorescein staining to rule out corneal involvement.

Skin exposures require irrigation with fluid and local wound care. Some individuals may develop a contact dermatitis.

Most oxalate exposures do not require any follow-up.


Nearly all cases of houseplant exposures involving oxalate-containing plant species are managed at home in consultation with a regional poison control center. Poison control centers may be helpful with plant identification, particularly if a fax copy or digital picture of the plant can be transmitted. Patients with eye involvement should follow up with an ophthalmologist.



Medication Summary

Analgesics may be required for pain. Antihistamines are indicated for significant oral and/or laryngeal edema.


Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort, which is beneficial for patients who have sustained trauma or sustained injuries.

Acetaminophen (Tylenol)

DOC for pain in patients with documented hypersensitivity to aspirin or NSAIDs, with upper GI disease, or who are taking oral anticoagulants.

Ibuprofen (Motrin, Advil)

DOC for patients with mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.


Class Summary

Treatment for significant oral and/or laryngeal edema.

Diphenhydramine (Benadryl)

For symptomatic relief of symptoms caused by release of histamine.