The Gross Reason You Might Be Allergic To Fish
Sometimes you learn a little bit more than you really need to know on Reddit. This is often the case on the r/todayilearned thread, especially a couple of months back when user mamaaaoooo started a post by noting that "if you allow bacteria like E. coli to grow in food, you can cook the E. coli out, but you can't cook out all the toxins they leave behind, which make you horribly sick after consumption."
To that, user DoomGoober rocked many people's worlds by noting a similar concept, specifically related to parasitic worms sometimes found in fish. "Cooking or freezing the fish kills the worms, but some people are still allergic to the byproducts the worms leave in the fish flesh," DoomGoober explained.
User bleckers makes it all even less appetizing, "Or when fish like salmon decomposes, the amino acid histidine converts into histamine. So some people get a severe reaction to the excessive histamine content."
Sadly, neither of them is wrong. Although, we'd very much like them to be.
Two ways fish can really mess you up
First, the fish worms. Per Allergy Link, the fish parasite in question is Anisakis simplex, which is a major allergen. Similar to an actual fish allergy, exposure to the parasite can cause serious symptoms, up to and including anaphylactic shock. "While Anisakis larvae can be killed by freezing or cooking, they can still trigger allergies after being killed, so people with Anisakis allergies should avoid fish and shellfish altogether," the organization noted.
Now, onto the histamine issue. This is actually known as scombroid poisoning, and usually occurs after ingesting canned, smoked, or fresh fish that were not properly stored or processed. In fact, this is one of the leading causes of death related to fish intake, according to the Canadian Medical Association Journal. Scombroid poisoning is often misdiagnosed because the symptoms are the same as a regular fish allergy, including flushing, palpitations, rash, headache, dizziness, burning of the mouth/throat, sweating, vomiting, diarrhea, respiratory distress, etc. The symptoms start roughly 10 to 90 minutes after ingestion, and can last up to 36 hours. Diagnosis is made by either measuring histamine levels in the suspected food, or by checking the patient's histamine metabolite level in urine/histamine level in plasma.
So, the next time you have trouble with fish, don't forego seafood altogether. It could be a random set of circumstances at hand, rather than an actual fish allergy. Gross circumstances, but random nonetheless.