Anyone who eats contaminated shellfish is at risk for illness or death. Early symptoms include tingling of the lips and tongue, which may begin within minutes of eating poisonous shellfish or may take an hour or two to develop. Depending upon the amount of toxin a person has ingested, symptoms may progress to tingling of fingers and toes and then loss of control of arms and legs, followed by difficulty in breathing. Some people have experienced a sense of floating or nausea. If a person consumes enough poison, muscles of the chest and abdomen become paralyzed.
Death can result in as little as two hours, as muscles used for breathing become paralyzed.
Paralytic shellfish poison is rarely associated with a red tinge to the water. Reddish coloration of the water is more commonly associated with other, non-toxic organisms. Blooms occur in clean waters as well as in polluted waters. Also, the toxin can remain in shellfish long after the algae bloom is over. Toxin can be present with no visible signs.