Ricin or Abrin Poisoning


Summary statement

Ricin and abrin are potent biological toxins that are derived from plant sources (castor beans and rosary peas, respectively). More is known about ricin toxicity; however, abrin toxicity is similar in its mechanism of action. In the body, these toxins inhibit protein synthesis leading to cell death. Clinical manifestations are dependent on the route of exposure. Ingestion typically leads to profuse vomiting and diarrhea followed by multisystem organ failure and possibly death within 36 to 72 hours of exposure. Inhalation typically leads to respiratory distress, fever, and cough followed by the development of pulmonary edema, hypotension, respiratory failure, and possibly death within 36 to 72 hours.

The amount and route of the exposure to ricin or abrin and the premorbid condition of the person exposed will contribute to the time of onset and the severity of illness. For example, the inhalation of ricin or abrin would be expected to lead to a quicker onset of poisoning and to cause a more rapid progression of poisoning compared with the ingestion of either of these toxins, given the same exposure amount.

Signs and symptoms of exposure

The following is a more comprehensive list of signs and symptoms that may be encountered in a person exposed to ricin or abrin. The list does not convey prioritization or indicate specificity. Also, partial presentations (an absence of some of the following signs/symptoms) do not necessarily imply less severe disease.


  • Abdominal pain
  • Abnormal liver function tests
  • Diarrhea (non-bloody or bloody)
  • Multiple ulcerations and hemorrhages of gastric and small-intestinal mucosa on endoscopy
  • Vomiting


  • Cough
  • Chest tightness
  • Dyspnea
  • Hypoxemia
  • Non-cardiogenic pulmonary edema

Skin and mucous membranes

  • Redness and pain of eyes and skin


  • Dehydration
  • Fever
  • Fatigue
  • Muscle pain
  • Weakness

Other organs

  • Cardiovascular collapse due to hypovolemia
  • Convulsions or seizures (uncommon)

Laboratory Findings (non-specific)

  • Hematuria
  • Increased liver function tests
  • Increased renal function tests
  • Leukocytosis or increased white blood cell count
  • Metabolic acidosis

Note: The actual clinical manifestations of a ricin or abrin exposure may be more variable than the syndrome described above.

Differential diagnosis


  • Exposure to pyrolysis byproducts of organofluorines (Teflon, Kevlar)
  • Oxides of nitrogen
  • Ozone
  • Phosgene
  • Staphylococcal enterotoxin B


  • Amatoxin containing mushrooms
  • Arsenic
  • Caustics
  • Colchicine
  • Enteric pathogens
  • Iron
Page last reviewed: April 4, 2018