With appropriate supportive care, the outcome is good with no identified long-term sequelae. Some patients describe weakness or fatigue for several days after paralytic shellfish poisoning.
Without adequate supportive care, severe cases of saxitoxin and tetrodotoxin poisoning can have mortality as high as 50%.[15]Lago J, Rodriguez LP, Blanco L, et al. Tetrodotoxin, an extremely potent marine neurotoxin: distribution, toxicity, origin and therapeutical uses. Mar Drugs. 2015 Oct 19;13(10):6384-406.
https://www.mdpi.com/1660-3397/13/10/6384
http://www.ncbi.nlm.nih.gov/pubmed/26492253?tool=bestpractice.com
[16]Cavazzoni E, Lister B, Sargent P, et al. Blue-ringed octopus (Hapalochlaena sp.) envenomation of a 4-year-old boy: a case report. Clin Toxicol (Phila). 2008 Sep;46(8):760-1.
https://www.tandfonline.com/doi/full/10.1080/15563650701601790
http://www.ncbi.nlm.nih.gov/pubmed/19238736?tool=bestpractice.com
[25]Hoffman RS, Howland MA, Lewin NA, et al. Goldfrank’s toxicologic emergencies. 10th ed. New York: McGraw-Hill Education; 2015. Complications and death rates may be higher in children than adults.[2]Centers for Disease Control and Prevention. CDC Yellow Book 2024: health information for international travel. Section 4: environmental hazards & risks - food poisoning from marine toxins. May 2023 [internet publication].
https://wwwnc.cdc.gov/travel/yellowbook/2024/environmental-hazards-risks/food-poisoning-from-marine-toxins
Weakness can persist for weeks.[25]Hoffman RS, Howland MA, Lewin NA, et al. Goldfrank’s toxicologic emergencies. 10th ed. New York: McGraw-Hill Education; 2015.
Less than 40 known human deaths can be attributed to conotoxin envenomation; therefore, little is known about the mechanism of death and the prognosis after envenomation.[43]Kohn AJ. Human injuries and fatalities due to venomous marine snails of the family Conidae. Int J Clin Pharmacol Ther. 2016 Jul;54(7):524-38.
http://www.ncbi.nlm.nih.gov/pubmed/27285461?tool=bestpractice.com
Although some envenomations can result in only sting-like symptoms, some estimates suggest that mortality can reach 70% without appropriate medical care.[25]Hoffman RS, Howland MA, Lewin NA, et al. Goldfrank’s toxicologic emergencies. 10th ed. New York: McGraw-Hill Education; 2015.