Allergic to shellfish. Why iodine?

Hi Atlanta,

It sounds like you have an allergy to the iodine products in shellfish and in many other parts of our daily lives including MRI's and Cat Scans. There is a conversation here that was started by Crab Wary, where lots of folks in the same boat as you realized they had an allergy to iodine by finding out they were allergic to shellfish. Some found out the hard way! 

There is a section here about drug allergies that also says the second most common allergy after penicillian is iodine common in most contrast procedures like xrays and such. You can read the entire article here.  

I hope this helps. You are not alone in this!! Stay in touch and let us know how you are doing!

Vicki M

Hi Babs,

I am no doctor, but it sounds like you had a drug interaction with the antibiotic and prilosec. According to gicare.com, prilosec might hamper the absorption of an antibiotic which would make it difficult for the antibiotic to work. You can also read about the medicines that are commonly prescribed for acid reflux here in the drugs database.

Are there interactions with other drugs?

An interaction generally means that one drug may increase or decrease the effect of another drug. Also, the more medications a person takes, the more likely there will be a drug interaction.

Interactions with this drug may occur with the following:

• diazepam (Valium)
• phenytoin (Dilantin)
• blood thinners (Coumadin)

Certain other drugs require stomach acid to be changed into their active form to be absorbed. Since omeprazole eliminates stomach acid so effectively, the absorption of the following drugs may be adversely affected:

• ampicillin (Polycillin, Omnipen)
• digoxin (Lanoxin)
• iron preparations
• ketoconazole (Nizoral)

If you take any of the above medications, ask your physician. It is okay to take antacids.

I hope this helps a little. Please stay in touch and let us know how you are doing!

Vicki M

Hi Atlanta,

I am tuning in a little late but I wanted to clarify a couple of issues. Iodine allergy and shellfish allergy are not related. This has been a misconception for a number of years. I review allergy literature every year looking for a change in this position, based on research, but there has been no change.  Shellfish does concentrate iodine when in sea water but the iodine is not the cause of shellfish allergy. Shellfish protein causes the allergic reaction.

 When allergist test patients for allergy to shellfish whether by blood test or skin test, iodine is not involved at all. The most common form of iodine allergy we currently see is related to contrast allergy, associated with radioiodine preparations.

Unfortunately medical staff still question patients about allergy to iodine before infusing iodinated contrast but they are propagating a misconception. When I am called about this (less common now) I inform medical staff that allergy to shellfish alone does not require any further intervention when iodine contrast infusion is being considered. A history of reaction to iodine contrast or other form of iodine product (not iodized salt) would warrant special preparation.

Later in the follow-up comments you mentioned a concern you have about Prilosec, antibiotics and possible reactions to them. The symptoms you had suggest a drug reaction. I think you may be intolerant to both Prilosec and the antibiotic you had. Both medications should be avoided until you discuss this with a doctor, preferably a board certified allergist. Further exposure could result in a more severe or fatal reaction. There are different types of drug reactions you can have that may not be related to classic allergy or dependent on drug interaction.

Good Luck!

J. Thompson, MD

I would like to comment on the iodine and shellfish allergy issues, and ask a question.

I am 51 and at 18 had a most severe reaction (grotesque swelling, pus-filled rash, etc.) to iodinated contrast media for a gall bladder test.  It was next to impossible to get any reliable information about this.

What I was told is that cretinism is associated with outright iodine ALLERGY, and that the correct term for my reaction is hypersensitivity.  (Since I'm typing my own post here, I trust you can tell I do not have a subnormal IQ.)

After that, I avoided iodine.  I did some amateur tests on myself with topical iodine preparations and they also created itching, swelling, and more disgusting stuff.  I also have a dreadful reaction to povidone-iodine preparations (like Betadine) and have fought with nurses who tried to approach me with it when hospitalized (I pray I am always conscious enough to do this!).

The amount of iodine in salt is not enough to provoke a reaction, but I use natural seasalt anyway, for various reasons. One warning: multi-vitamins! The ONLY one I have found not containing iodine is Nature's Life One Daily Multiple/Iron & Iodine Free.  Another warning: seaweed and kelp products, whether as food, in supplements or beauty products.

Anyway, all along I loved shellfish and ate a lot of it. At 49, for reasons unknown, I had a sort of two-week shellfish binge--it was all I wanted to eat.  I started reacting with throat swelling, dizziness, bloating, redness and itching, but not in a life-threatening way. Some of these symptoms lasted for FIVE WEEKS. I felt like there was a propane torch under my skin and sleep was very difficult. I took antihistamines, but due to diabetes cannot have cortisone shots.

Two weeks ago I ate at my longtime favorite Asian restaurant. I order meat & poultry dishes and warn them to knock off the fish sauce (contains boiled-down shellfish). This time they obviously forgot. The amount of shellfish would have been micrograms, so the reaction was not as acute.

But two weeks later, my reaction continues to come & go in waves--this is what I do not understand, and would appreciate some clarification. As I type, my lips are tingling and my back & shoulders are covered with bloodied scratches, my feet and hands are swollen.  I haven't seen another post that talked about duration of symptoms of a non-emergency kind. Like others who have posted, I am now petrified of all seafood.

Also, re Prilosec:  I used to take this and am happy I weaned myself off of it, using the non-Rx products PhChoice and Twinlab Digestive Enzymes.  However, while on it I was prescribed antibiotics and got the classic swollen joints w/ rash.  I was told I have to now avoid penicillin, and read somewhere that taking antibiotics with Prilosec can indeed induce this reaction.