If you have shellfish allergies you might be having a reaction to sea salt.
Read this post from another forum. It's enlightening.

"I became allergic to shellfish at age 42 after eating a good deal of it in my adult life. Naturally I stopped eating it after that, which left me as a vegetarian, basically. Then I tried to eat mostly organic foods and found that if I ate prepared foods at health food stores or restaurants, I would frequently have the same reaction as though I had eaten shellfish.

I finally determined that the culprit was Sea Salt , and was informed by a doctor at the Mayo Clinic that sea salt contains "marine copolymers" (which another doctor told me was a fancy word for the microscopic shellfish that are contained in sea salt). So while I admire the properties of sea salt and all the wonderful things it can do for many people, I feel that those who are allergic to shellfish should be warned that sea salt may cause them to have allergic reactions. (In my case, that's a huge swelling of the glands in my neck, and lots of pain.)

I also avoid milk, but was unable to switch to commercially prepared soy or rice milk, as I have found not a single manufacturer of those milks that doesn't include sea salt as an ingredient."

If they're using sea salt and just labeling it salt, that's wrong. Demand that it say "sea salt". I cannot afford allergic reactions that make me sick for eight hours.