Delayed Anaphylaxis Shellfish | Allergy

Delayed Anaphylaxis with Shellfish

by Allergy Guy

Delayed anaphylaxis is disbelieved by many doctors but is mainstream.  It is known to occur with meat. Delayed anaphylaxis may happen with shellfish as well.

I have two reasons to suggest that meat may not be the only trigger for delayed anaphylaxis.  Firstly, if there is one known and repeatable example of delayed anaphylaxis, than why not others?  It would be hard to prove no other instances exist.  Secondly, I now have anecdotal evidence in the form of a comment someone left on this website.Desi French left the following comment:

I became allergic to crustaceans in my early 20s. I have been in full-blown anaphylactic shock; huge hives, not breathing, tunnel, light and all.

Luckily I had just arrived at the ER and they saved me. But I have never once had a reaction sooner than 24 hours after ingesting the shellfish.

All events after the first one were accidental; caused mainly by people lying to me about the content of menu items in restaurants and once by there being shrimp in the Reuben sandwich I ordered. I didn’t think to ask!

I had no idea that my pattern was so rare until I met an ER doc who refused to either believe me or treat me. He did call me the next day to apologize after he had done some research but I had to save my own life in his ER with my epi-pen.

The above example is shocking: an ER doctor refusing to treat a patient due to his own ignorance, but I’m sure it happens every day with an wide array of rare conditions that are not considered possible in the mainstream.  Kudos to the doctor to having the humility to call and apologize.  And clearly he was able to find sufficient evidence to convince himself that such conditions do exist.

What experiences have you had with delayed anaphylaxis?  Leave a comment and share your experiences and questions, especially about delayed anaphylaxis with shellfish.

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{ 8 comments… read them below or add one }

1 Jessica owen March 29, 2018 at 03:02

My husband has delayed reactions to shellfish. They can occur anywhere from 1 to 5 hours after ingestion. It started about 9 years ago with crayfish. (At the time he was on denial about being allergic as he had been eating shellfish all his life.) So over the years he purposely ate it and reacted. He was always fine with lobster, shrimp and crab until recently, and one by one, he has had reactions over the last year. Tonight, he woke me up with a reaction. He ate shrimp around 9 pm. At 1:30 AM, he was having abdominal pain, diarrhea, itching, hives, his hands were locked up, and he felt like he was going to faint. Usually, it is just psin, diarrhea, itching, hives, but it is always well after ingestion.


2 Kerry January 12, 2016 at 18:23

I experienced delayed anaphylaxis the other night after eating rock shrimp. I have other food allergies – have never had reaction to fish. I woke up in the middle of the night with severe stomach cramps, vomiting, rash on my face, itchy throat & mouth. Difficulty breathing, wheezing, coughing, etc. I have never had a delayed reaction to anything in the past. It has always been immediate.


3 Desi January 26, 2016 at 22:55

After reading about your experience, I think that you might want to print out this column and bring it to the doctor. There is nothing more terrifying than to know that your life is in danger. A delayed shellfish allergy is apparently so rare that those of us who experience it need to arm ourselves with knowledge as well as with epi-pens.


4 Jim July 20, 2013 at 09:04

I had a delayed anaphylactic shock about 4 hours after eating shrimp and oysters. It was my first time ever to have an allergic reaction to shellfish of any kind. Luckily the EMT’s were located very close to my house. After an overnight stay at the local hospital, the releasing physician still did not believe it was as a result of the shrimp/oysters. I have an appointment with an allergist to get a definitive answer as to the cause of my episode. Needless to say after 69 years of no allergies, this was a big surprise!


5 Amanda April 18, 2013 at 00:58

I ate shellfish on Sunday and it is now Wednesday night and am still having allergic reactions. Ended up at the dr’s today because my lip was swelling . I now have an epi pen and a fear of eatin out.


6 Winny October 5, 2012 at 23:57

I thought I was having delayed reactions to shellfish until I found out that I had a mammalian meat allergy (which is known for its delayed reactions).
Here is how it actually happened to me (I figured it out after the other diagnosis)
#1) I have had a bad seafood allergy from which I will have anaphylactic episodes
#2) I don’t eat out often because of multiple food related allergies but when I did it was often with a group of people from work
#3) They like to eat seafood, which I couldn’t tolerate, so I would order Steak or pork, thinking this was the safe alternative.
#4) Hours later I would be hiving, and having an anphylactic attack.
#5) Used to having this with seafood, I always thought it was cross contamination at the restaurant so that was why it took so long to react, OR I thought the reaction was to whatever it was I ate 20 minutes before the attack!!.
BUT this said, the delayed anaphylaxis is due to a fat related enzyme. Shellfish have a lot of fat in them, I don’t see why it couldn’t happen. Maybe the delay is not the specific allergy but the delay in digesting the fat molecules which carry the allergen???


7 Desi French September 26, 2012 at 03:03

I have heard that delayed anaphylaxis is much more common in Hawaii and Australia than it is here in mainland USA. Why this should be the case is really puzzling.


8 Allergy Guy September 26, 2012 at 08:51

One reason might be that they eat more shellfish in those countries. That would sensitise more people.


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