Who gets shellfish allergy?

Although shellfish allergy occurs more often in adults and older children, it can appear at any age and can be caused by foods that had been previously eaten without any problems. Most people who are allergic to one type of shellfish are often allergic to other types of shellfish. Many people with shellfish allergy will not lose the allergy.

What are the symptoms?

Allergic reactions to foods usually begin within minutes to a few hours after eating the food. The severity of symptoms can vary widely from one person to another. Mildly allergic persons may have itching and a few hives while severely allergic persons may experience severe, life-threatening symptoms such as breathing problems or swelling of the throat. The symptoms of food allergy may include any or several of the following:

  • Itching
  • Hives
  • Eczema
  • Tingling or swelling of the lips, tongue or throat
  • Chest tightness, shortness of breath or difficulty breathing
  • Wheezing
  • Abdominal pain
  • Nausea, vomiting or diarrhea
  • Dizziness
  • Fainting
  • Anaphylaxis: sudden, severe, potentially fatal, systemic allergic reaction that can involve several areas of the body

How do I avoid exposure?

If you have a shellfish allergy, strict avoidance of shellfish is the only way to prevent a reaction. The Food and Drug Administration (FDA) requires food manufacturers to list common food allergens on food labels in plain terms to make it easier to identify the food allergens. Food labels must clearly list eight allergens which account for almost 90 % of all food allergies: cow’s milk, soy, wheat, egg, peanut, tree nuts, fish, and shellfish.

The common allergens are listed either within the ingredient list or after the list. For example, if a product contains abalone, a species of shellfish, the product's label should list the term “shellfish” either after the term abalone, or state “contains shellfish” after the list of ingredients. The FDA currently does not require manufacturers to state if the food was processed in a facility that also processes the 8 common food allergens.

Anyone allergic to shellfish should avoid the following ingredients and foods:

  • Abalone
  • Clams (such as cherrystone, littleneck, pismo, quahog)
  • Cockle
  • Conch
  • Crab
  • Crawfish and crayfish
  • Lobster
  • Mollusks
  • Mussels
  • Octopus
  • Oysters
  • Scallops
  • Shrimp and prawns
  • Snails
  • Squid (calamari)

Other things to keep in mind if you have shellfish allergy:

  • Shell-fish protein can become airborne during cooking and cause an allergic reaction.
  • Some people may have a reaction from handling shellfish.
  • Non-shellfish foods prepared in a seafood restaurant may contain shellfish because of contamination.
  • Certain foods may contain shellfish products such as bouillabaisse, cuttlefish ink, fish stock, favoring including natural and artificial flavoring, imitation shellfish, seafood flavoring, and surimi.
  • Be cautious with fried foods as some restaurants use the same oil to fry seafood as well as non-seafood items.
  • Allergy to iodine, allergy to radiocontrast material, and allergy to seafood (fish and shellfish) are not related. If you have shellfish allergy, you do not need to worry about reactions with radiocontrast material or iodine.

How can I be prepared?

  • Always know what you are eating and drinking.
  • Always check the label ingredients before you use a product, even if the food was safe the last time you ate it. Manufacturers can change recipes and a shellfish-containing food may be added to the recipe.
  • Teach children with shellfish allergy not to accept food from classmates or friends.
  • When dining out, ask detailed questions about ingredients and how the food was prepared.
  • Wear a medical alert bracelet with information about your allergy or carry an alert card with you.
  • Talk with your doctor about how to prepare for a reaction. Mild reactions may be treated with oral antihistamines. If you have a severe allergy, your doctor may prescribe self-injectable epinephrine to carry with you at all times in case you have a severe reaction.


This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 12/28/2012…#11319