Iodine is a chemical compound used in some disinfectants and some chemicals used in X-ray procedures. Some people can have a severe intolerance to iodine, but it is not categorized as an allergic response.

Iodine is essential for thyroid function, and helps to maintain healthy cells and a healthy metabolic rate. Adverse reactions to iodine are not considered to be allergies, but some people can have an iodine intolerance.

Iodine is an ingredient in chemical agents such as radiocontrast agents, which help to improve visibility on X-ray images. A person who is sensitive to iodine may have an adverse reaction to these agents, and to certain iodine-containing disinfectants, such as Betadine.

Iodine is also an ingredient in certain foods that can cause a reaction in some people, but this is not the same as a food-related allergic reaction.

In this article, we look at symptoms of an iodine allergy, its relationship with shellfish allergies, and outlook.

Symptoms

Using Iodine on a cut that may have an iodine allergy
Iodine is an ingredient in some disinfectants.

Exposure to products containing iodine can cause various symptoms for people with an iodine sensitivity, including:

  • an itchy rash that develops over time (contact dermatitis)
  • hives (as urticaria)
  • anaphylaxis

Symptoms of anaphylaxis include:

  • pain in the abdomen
  • feeling nauseous or being sick
  • diarrhea
  • feeling confused
  • trouble breathing
  • heart palpitations
  • a change in alertness
  • feeling dizzy or lightheaded
  • hives
  • low blood pressure

The symptoms of a person going into anaphylactic shock include:

  • hives
  • swelling of the throat and tongue
  • shortness of breath

Anaphylactic shock is life-threatening, and people should seek medical help immediately if suspected.

Iodine allergy vs. shellfish allergy

People with a shellfish allergy will react to certain proteins found in shellfish. Shellfish include any marine creatures with shells, including crabs, shrimp, lobster, oysters, scallops, as well as squid and octopus.

However, shellfish allergies are not linked to iodine. A person with a shellfish allergy is not any more likely to react to the iodine used in medical practices than anyone else. Shellfish allergies usually occur due to specific proteins in fish, not iodine.

A person with a shellfish allergy may be allergic to all shellfish or certain kinds. Allergic reactions can range from mild to severe, and in some cases might be life-threatening. Anyone with a severe allergy who suspects they have consumed shellfish should seek immediate medical help.

A doctor will be able to confirm whether someone has a shellfish allergy by running skin prick tests and blood tests.

Which other foods are high in iodine?

Cranberries in a wooden bowl
Cranberries are rich in iodine.

Some foods have a high iodine content, though the amount of iodine can be dependent on how much iodine was present in the soil, the farming practices, and the time of year.

Some foods that are rich in iodine include:

  • fish
  • dairy products
  • sea vegetables, such as kelp, arame, or kombu
  • cranberries
  • strawberries
  • beans
  • potatoes

Outlook

If a person suspects they have an iodine allergy, they should talk to their doctor who can run tests to confirm either way.

If a doctor diagnoses an iodine allergy, they will be able to advise the person on which foods, treatments, or medications they should avoid to minimize reactions.

An individual should make sure that all medical professionals are aware of their iodine allergy before having any medical treatment.