ACMT Toxicology Visual Pearl: Household Plant Gone Wrong

1. Calcium oxalate

Calcium oxalate, found in popular houseplants such as dumb cane (Dieffenbachia seguine), causes both physical and chemical irritation to skin and mucous membranes.

Background

In children under five years of age, ingestion of household plants is one of the leading causes of poison control inquiries in the US. [1] Common household plants such as Philodendron and Dieffenbachia contain calcium oxalate, which causes physical and chemical irritation to the skin, mucous membranes, and conjunctival surfaces. [2,3]   The 2022 Annual Report of the American Association of Poison Control Centers’ National Poison Data System reported no major outcomes and no deaths from oxalate plant exposures. [1]

How does calcium oxalate cause injury? [2-4]

• Calcium oxalate forms tiny needle-like crystals called raphides that cause microtrauma and pain when they encounter skin, mucosa, and conjunctival surfaces.
• Raphides also cause chemical injury via proteolytic enzymes and bradykinin.

How does calcium oxalate toxicity present? [4-7]

Symptom onset is rapid following exposure and can include the following:

• Localized erythema and edema of the skin (contact dermatitis)
• Intraoral erythema, edema, blistering
• Excessive drooling
• Slurred or garbled speech
• Esophagitis or laryngeal edema, if sufficiently contacted or swallowed
• Keratoconjunctivitis or corneal abrasion
• There are rare cases of life-threatening events or death [8-10]

How do you treat calcium oxalate toxicity? [2,7,8]

• Medical management focuses on symptomatic and supportive care.
• Decontamination is important to limit exposure and can be accomplished with soap and water to exposed skin, or copious water irrigation to eyes and mucous membranes for at least 15 minutes.
• Systemic and/or local analgesia.
• Antihistamines for significant swelling.
• Steroids are not beneficial unless severe swelling causes concern for airway compromise.
• Airway assessment and support as needed.
• Slit lamp exam with fluorescein staining after ocular exposure, followed by ophthalmology consultation if there is evidence of keratoconjunctivitis and/or corneal injury.
• Disposition and observation time are based on clinical severity of pain and swelling.

Bedside Pearls

• Calcium oxalate is a toxin found in many household plants.
• Commonly affected areas are the mouth, skin, and eyes.
• Patients present with contact dermatitis, oral pain and swelling, and excessive drooling.
• Decontamination with water is important to limit further exposure.
• Treatment focuses on symptomatic and supportive care.
• Rarely, life-threatening complications such as airway compromise are reported.