Tetrodotoxin Toxicity Clinical Presentation

Updated: May 24, 2018
  • Author: Theodore I Benzer, MD, PhD; Chief Editor: Asim Tarabar, MD  more...
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  • The first symptoms occur 15 minutes to several hours postingestion of tetrodotoxin-containing food. A recent report on toxicity found that initial symptoms may occur up to 20 hours after ingestion.

  • Initial symptoms include lip and tongue paresthesias, followed by facial and extremity paresthesias and numbness.

  • Salivation, nausea, vomiting, and diarrhea with abdominal pain develop early.

  • Motor dysfunction with weakness, hypoventilation (may be from dysfunction of central and peripheral nervous systems), and speech difficulties then develop. A rapid ascending paralysis occurs over 4-24 hours. Extremity paralysis precedes bulbar paralysis, which is followed by respiratory muscle paralysis. Deep tendon reflexes are preserved early in the course of paralysis.

  • Finally, cardiac dysfunction with hypotension and dysrhythmias (bradycardia), central nervous system (CNS) dysfunction (eg, coma), and seizures develop. Patients with severe toxicity may have deep coma, fixed nonreactive pupils, apnea, and loss of all brain stem reflexes.

  • Death can occur within 4-6 hours. Typically, death occurs from respiratory muscle paralysis and respiratory failure.



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  • Loss of sensory and motor neuron function is a prominent finding.

  • Ascending paralysis with respiratory depression.

  • Cyanosis occurs with respiratory failure.

  • Hypotension can occur with myocardial dysfunction.

  • Cardiac rhythm disturbances, especially bradycardia, atrioventricular (AV)–nodal block, and bundle-branch block, can be life threatening.

  • GI effects are not prominent, but vomiting and abdominal tenderness can occur.



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  • Ingestion of tetrodotoxin causes the syndrome.

  • Almost all toxicity is caused by the ingestion of fugu, but other species of animals have been shown to produce tetrodotoxin (eg, California newt, parrot fish, blue-ringed octopus). A death from ingestion of tetrodotoxin from a California newt has been documented.