Scombroid is caused by ingestion of preformed histamine on skin of fish.

• Naturally occurring histidine on scaly fish converted to histamine by surface bacteria - often fish left out too long, refrigeration will prevent the conversion.
• Bacteria responsible are Morganelli morganii and K. pneumoniae
• Fish: tuna, mahi mahi, amberjack, bonito, mackerel, albacore
• Fish usually appears normal though meat may tast peppery
• Patient presents minutes/hrs flushed, urticaria, HA, N/V
• Self-limited and improve within hrs even without treatment
• Antihistamines and rarley epinephrine will be needed