Patients sometimes describe a peppery or bitter taste to the fish, but often the fish tastes completely normal. A constellation of symptoms, including skin flushing, throbbing headache, oral burning, abdominal cramps, nausea, diarrhea, palpitations, a sense of unease, and, rarely, prostration or loss of vision characterize scombroid. Physical signs may include a diffuse blanching erythema, tachycardia, wheezing, and hypotension or hypertension. Persons who are very young or elderly are at particular risk because of lower physiologic reserve. Additionally, persons with asthma are vulnerable because they may experience acute exacerbation of their asthma.
Diagnosis usually is based upon history and physical examination.
If blood pressure is abnormal, an ECG may be warranted. Histamine receptor type 1 and histamine 2 blockers diminish the effects of histamine. In rare instances in which patients are seriously ill and present acutely, charcoal may be of some benefit. TTX is one of the most potent nonprotein poisons found in nature, and exposure can result in rapid death. Symptoms occur within 15 minutes of ingestion but may be observed as late as several hours later.