Oxalate Poisoning


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:


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.  However, there are case reports of severe oropharyngeal inflammation and edema, with impending obstruction of the upper airways.[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]

History and Physical Examination

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

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.

Acetaminophen (Tylenol)

Clinical Context:  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)

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

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.

Diphenhydramine (Benadryl)

Clinical Context:  For symptomatic relief of symptoms caused by release of histamine.

Class Summary

Treatment for significant oral and/or laryngeal edema.


Jason F Kearney, MD, MBA, Facility Medical Director, Emergency Department, TeamHealth Providence Centralia

Disclosure: Nothing to disclose.


William K Chiang, MD, Associate Professor, Department of Emergency Medicine, New York University School of Medicine; Chief of Service, Department of Emergency Medicine, Bellevue Hospital Center

Disclosure: Nothing to disclose.

Specialty Editors

John T VanDeVoort, PharmD, Regional Director of Pharmacy, Sacred Heart and St Joseph's Hospitals

Disclosure: Nothing to disclose.

Chief Editor

Sage W Wiener, MD, Assistant Professor, Department of Emergency Medicine, State University of New York Downstate Medical Center; Director of Medical Toxicology, Department of Emergency Medicine, Kings County Hospital Center

Disclosure: Nothing to disclose.

Additional Contributors

Miguel C Fernandez, MD, FAAEM, FACEP, FACMT, FACCT, Associate Clinical Professor, Department of Surgery/Emergency Medicine and Toxicology, University of Texas School of Medicine at San Antonio; Medical and Managing Director, South Texas Poison Center

Disclosure: Nothing to disclose.


Michael Hodgman, MD Assistant Clinical Professor of Medicine, Department of Emergency Medicine, Bassett Healthcare

Michael Hodgman, MD is a member of the following medical societies: American College of Medical Toxicology, American College of Physicians, Medical Society of the State of New York, and Wilderness Medical Society

Disclosure: Nothing to disclose.


  1. Poli LP, Temponi LG, Coan AI. Floral vasculature and its variation for carpellary supply in Anthurium (Araceae, Alismatales). PeerJ. 2017. 5:e2929. [View Abstract]
  2. Wang B, Han L, Chen C, Wang Z. The complete chloroplast genome sequence of Dieffenbachia seguine (Araceae). Mitochondrial DNA. 2015 Jul 8. 65 (4):1-2. [View Abstract]
  3. Gardner DG. Injury to the oral mucous membranes caused by the common houseplant, dieffenbachia. A review. Oral Surg Oral Med Oral Pathol. 1994 Nov. 78(5):631-3. [View Abstract]
  4. Lin TJ, Hung DZ, Hu WH, Yang DY, Wu TC, Deng JF. Calcium oxalate is the main toxic component in clinical presentations of alocasis macrorrhiza (L) Schott and Endl poisonings. Vet Hum Toxicol. 1998 Apr. 40(2):93-5. [View Abstract]
  5. Zhong LY, Wu H. [Current researching situation of mucosal irritant compontents in Araceae family plants]. Zhongguo Zhong Yao Za Zhi. 2006 Sep. 31(18):1561-3. [View Abstract]
  6. Gummin DD, Mowry JB, Spyker DA, Brooks DE, Osterthaler KM, Banner W. 2017 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 35th Annual Report. Clin Toxicol (Phila). 2018 Dec 21. 54 (10):1-203. [View Abstract]
  7. Mintzker Y, Bentur Y. [DIEFFENBACHIA POISONING]. Harefuah. 2018 Oct. 157 (10):631-633. [View Abstract]
  8. Baab S. Conjunctivitis, Allergic. Kinzer EE. StatPearls. Treasure Island (FL): StatPearls Publishing; 2018 Jan.
  9. Nair PA. Dermatitis, Contact. Atwater AR. StatPearls. October 4, 2017. Treasure Island (FL): StatPearls Publishing; 2018 Jan.



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