Domoic acid is the cause of amnestic shellfish poisoning. Severe symptoms of amnestic shellfish poisoning are altered mental status, memory loss, arrhythmias, hypotension, and seizure. Other associated symptoms include gastrointestinal disturbances and focal neurologic signs such as hemiparesis and ophthalmoplegia. Symptoms usually begin about 6 hours after ingestion but may occur as late as 2 days after ingestion. Neurologic and memory symptoms often persist even after the other symptoms of poisoning have improved and can be chronic in some instances.

Domoic acid is a neurotoxic amino acid produced by algae. Humans indirectly ingest the toxin through shellfish. Outbreaks have occurred on the coasts of North America and Europe.

There is no commonly available test to directly detect toxin ingestion. Treatment is supportive.