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Food Poisoning from Fish: Ciguatera Eating Contaminated Fish Can Cause Unusual Symptoms

dead fish on ice

The Bottom Line

Ciguatera fish poisoning is caused by eating fish that have themselves eaten fish contaminated with a toxin called ciguatoxin. Ciguatoxin cannot be detected by taste or appearance or prevented by cooking or freezing the fish. Treatment is available, but symptoms may last for months or years.

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The Full Story

What you can't smell can't hurt you, right? Wrong! Eating some kinds of fish can cause some pretty unusual and dramatic symptoms.

Ciguatoxin is produced by a type of algae associated with coral reefs. Small plant-eating fish eat the algae, and are then eaten by larger fish, again by yet larger fish, and so on up the food chain. This causes ciguatoxin to concentrate in larger fish. More than 400 species of fish are known to have caused ciguatera poisoning, but the most common are older, larger fish which have been eating contaminated fish during their life spans: grouper, barracuda, snapper, jack, mackerel, triggerfish, and others. Even though contaminated fish are from tropical and sub-tropical fish, ciguatera poisoning occurs anywhere these fish are shipped for consumption.

Ciguatoxin usually causes symptoms within a few hours of eating the fish, but symptoms can be delayed up to 24 hours. Patients can experience nausea, vomiting, diarrhea, muscle weakness, joint aches, headache, dizziness, and low blood pressure. Ciguatoxin can also cause unusual neurologic symptoms because of swelling and dysfunction of nerves. One characteristic and surprising symptom is "hot-cold reversal"; hot items feel cold and cold items feel hot. Imagine drinking iced coffee that feels warm! Other patients have reported numbness around the mouth and even the sensation that their teeth are falling out. Most people are better in a few days, but in some cases symptoms last for months or even years. Symptoms may recur after eating fish, alcohol, nuts, caffeine, chocolate, chicken and eggs.

Most patients recover without treatment; however, those with significant dehydration require treatment with fluids and medications for nausea. Available treatment options for neurologic symptoms are not always effective.

There is no specific way to prevent ciguatera, but avoiding eating larger tropical fish may reduce the chance of exposure to ciguatoxin. Recurrence of symptoms can be prevented by avoiding fish, alcohol, nuts, caffeine, chocolate, chicken, and eggs for several months after the diagnosis. Individuals have reported pain following intercourse with infected individuals, suggesting the toxin may be sexually transmitted. For this reason, it is recommended to use barrier protection for patients with active symptoms. Also, ciguatoxin is secreted in breast milk and has caused diarrhea and facial flushing in breastfed infants. Mothers should consider pumping and dumping their breastmilk if they are actively symptomatic.

Keep others safe, too. If anyone develops symptoms of ciguatera poisoning from fish from a store or restaurant, be sure to let the facility and the health department know. That might prevent someone else from becoming sick from eating the same fish.

For questions about ciguatera poisoning, or if you think someone is having a reaction to fish, go online to www.poison.org or call 1-800-222-1222.  Both options are free for the public, and available 24 hours a day.

Rose Ann Gould Soloway, RN, BSN, MSEd, DABAT emerita
Clinical Toxicologist

Maryann Amirshahi, PharmD, MD, MPH, PhD
Medical Toxicologist

Poisoned?

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Prevention Tips

  • Avoid eating large fish, at or near the top of the food chain, as they are most likely to cause ciguatera poisoning.
  • Avoid foods known to trigger recurrence for several months after a diagnosis of ciguatera.
  • Use barrier protection to prevent sexual transmission in symptomatic ciguatera patients. 
  • Breastfeeding mothers with active symptoms should consider pumping and dumping to avoid transmission of ciguatera to the baby.  

This Really Happened

A 56-year-old woman ate barracuda while on vacation in Aruba. Eight hours after eating the fish, she developed nausea, vomiting, abdominal cramping, and itching. She then developed numbness around her mouth and a tingling sensation in her arms and legs. The following day, she noted that when she washed her hands under cold water, she felt as though her hands were “on fire”. She experienced the same feeling in her feet when she walked on a cold floor. She returned home to the United States, and presented to an Emergency Department where ciguatera was diagnosed. At a follow-up visit with her primary care doctor one month later, she reported that nearly all of her previous symptoms had resolved, with the exception of pain in her legs.

For More Information

If you have a question about adverse reactions from itch mites or other bites or stings, get help with webPOISONCONTROL or call 1-800-222-1222. Both options are free for the public, and available 24 hours a day.

References

Friedman MA, Fernandez M, Backer LC, Dickey RW, Bernstein J, Schrank K, Kibler S, Stephan W, Gribble MO, Bienfang P, Bowen RE, Degrasse S, Flores Quintana HA, Loeffler CR, Weisman R, Blythe D, Berdalet E, Ayyar R, Clarkson-Townsend D, Swajian K, Benner R, Brewer T, Fleming LE. An Updated Review of Ciguatera Fish Poisoning: Clinical, Epidemiological, Environmental, and Public Health Management. Mar Drugs. 2017 Mar 14;15(3):72. 

Friedman MA, Fleming LE, Fernandez M, Bienfang P, Schrank K, Dickey R, Bottein MY, Backer L, Ayyar R, Weisman R, Watkins S, Granade R, Reich A. Ciguatera fish poisoning: treatment, prevention and management. Mar Drugs. 2008;6(3):456-79.

Patel M, Jutzy K. A Curious Case of Ciguatera Fish Poisoning in the Midwest and a Review for Clinicians. J Emerg Med. 2020 Mar;58(3):e109-e111.

Patient Page about ciguatera fish poisoning (The Journal of American Medical Association)

Poisoned?

Call 1-800-222-1222 or

HELP ME online

Prevention Tips

  • Avoid eating large fish, at or near the top of the food chain, as they are most likely to cause ciguatera poisoning.
  • Avoid foods known to trigger recurrence for several months after a diagnosis of ciguatera.
  • Use barrier protection to prevent sexual transmission in symptomatic ciguatera patients. 
  • Breastfeeding mothers with active symptoms should consider pumping and dumping to avoid transmission of ciguatera to the baby.  

This Really Happened

A 56-year-old woman ate barracuda while on vacation in Aruba. Eight hours after eating the fish, she developed nausea, vomiting, abdominal cramping, and itching. She then developed numbness around her mouth and a tingling sensation in her arms and legs. The following day, she noted that when she washed her hands under cold water, she felt as though her hands were “on fire”. She experienced the same feeling in her feet when she walked on a cold floor. She returned home to the United States, and presented to an Emergency Department where ciguatera was diagnosed. At a follow-up visit with her primary care doctor one month later, she reported that nearly all of her previous symptoms had resolved, with the exception of pain in her legs.