Please clarify allergies for me.


Is there any correlation with Sulfa, shellfish, latex, and iodine? A coworker tried to tell me that I need to ask if pts re allergic to shellfish if they are allergic to Sulfa? Is this true? It must be wrong. So confused! What do I need to know about allergies to these things?

MunoRN, RN

8,058 Posts

Specializes in Critical Care. Has 10 years experience.

Regardless of what they are allergic to you should determine all of their known allergies.

Long ago, it was thought that a seafood allergy was due to the high levels of iodine in seafood, yet even though this myth has been thoroughly debunked over the past 50 years, it still persists.

Plus, you can't actually be truly allergic to iodine. Iodine intake cannot be avoided, and Iodine is not capable of producing a true allergic reaction, and even if it was, it's physiologically impossible to live without iodine.

There aren't any well established cross sensitivities between sulfa, seafood, and latex (although seafood does contain some of the same amines that cause allergic reactions in sulfa). In general, someone with allergies has a higher probability of being allergic to other things as well, but you can't necessarily assume that someone allergic to one thing is allergic something else, unless there are known cross-sensitivities.

jadelpn, LPN, EMT-B

51 Articles; 4,800 Posts

You should always ask what a patient is allergic to, which should include everything--meds, food, enviromental, etc. Follow up with what type of allergic reaction they have. (rash, swelling, etc) I would not get into "well, are you allergic to this because of this" line of questioning, as then it could cause anxiety in patients--especially those who are allergic to a number of things. I make no comment when someone tells me they are allergic to something and it causes stomach upset (that is a sensitivity at most)--that is for the MD to discuss with the patient.


3,413 Posts

Has 38 years experience.

This topic is still so confusing. It comes up frequently. All Nurses Aug.10th 2010, "why betadine on skin for those with iodine/shellfish allergy" was a good discussion about it.

All I came away with from that discussion was don't doubt or question a patients allergy, no matter what evidence based studies may prove.

Unfortunately the whole issue is still as clear as mud to me. Asking if a patient is allergic to shellfish can't hurt.


21 Posts

Thanks guys. I understand the whole iodine thing, but the tech(?) was like, ask if they are allergic to shellfish if they are allergic to Sulfa? WTH? Ok well I ask a patient all of their allergies but this was a bit strange. English wasn't his first language so I'm thinking that is the confusion.


394 Posts

Don't know of any shellfish/Sulfa connection, but I learn something new every day! Sulfa and PCN are very common allergies, so they may be worth asking about if not mentioned.

nurseprnRN, BSN, RN

2 Articles; 5,114 Posts

This is a line of enquiry from people who don't understand allergy. Somebody heard that people with seafood allergy can be allergic to iodine (not true, BTW-- no iodine -> goiter, which is why salt is iodized and the incidence of goiter has plummeted in the decades since that was done). Therefore something slipped a cog and s/he thought s/he should ask all patients about seafood allergy and others. Sloppy, lazy.

Latex allergy is a different trip. All of these can be cross-allergenic with latex. (

  • apples, bananas, kiwi, peaches, plums, figs, grapes, melons, papaya, passion fruit, cherries, nectarines, pears, pineapple and strawberries
  • carrots, celery, raw potatoes, avocados and tomatoes
  • chestnuts and hazelnuts
  • wheat and rye

Whispera, MSN, RN

3,458 Posts

Specializes in psych, addictions, hospice, education.

When my son was a little guy, he had an xray with dye containing iodine and had a severe reaction to it. Hives and difficulty breathing. The doctor said he believed the culprit was the iodine, rather than whatever else was in the dye. He is also allergic to shellfish, and gets that same reaction. I'm allergic to sulfa; he's never had it. I wonder....

Allergy to sulfa means he's allergic to a class of drugs called sulfonamides (sp?). It has nothing to do with shellfish. Sulfites, on the other hand, are added as a preservative to some foods, including seafood. Sulfite and sulfa allergies are not at all the same.

Specializes in PCCN. Has 20 years experience.

I know there's an anecdotal association between sulfa allergies and splenda.not sure why. But I know splenda does not agree with me, and I have allery to sulfa meds- get terrible hives and rash.

Specializes in 4. Has 7 years experience.

I have never heard any of this but I am allergic to sulfa NOT shellfish nor latex. I do not eat meat but I do eat fish. No reactions yet (since 8/12).


4 Posts

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