Shellfish Allergies: An Overview

shellfishOne of the most common food allergies in the U.S. is an allergy to shellfish, which affects about 7 million Americans. Interestingly, shellfish allergies are the most common food allergies occurring in adults, and most shellfish allergies, about 60 percent, do not develop until adulthood. Recent studies show that shellfish allergies affect about 2.1 percent of American adults, but only 0.1 percent of children. Still, children can and do develop an allergy to shellfish.

Once developed, a shellfish allergy tends to be life-long, and can cause reactions ranging from very mild to quite severe. Like many food allergies, symptoms may include headaches, facial swelling and nausea, as well as an itchy mouth, hives or difficulty breathing. As with other allergies, an extreme reaction called anaphylaxis may occur, which involves a life-threatening drop in blood pressure. Because of this, it is recommended that anyone diagnosed with a shellfish allergy carry an EpiPen or similar epinephrine injector at all times. Shellfish allergies, especially allergies to crustaceans such as lobster and shrimp, tend to be particularly severe, so extra caution is highly recommended.

Similar Allergens

Shellfish allergies are often associated with fish allergies, and the two are often grouped together into what is called “seafood allergies.” However, it should be noted that shellfish and fish (or finfish) are biologically distinct, so someone with a shellfish allergy will not necessarily have a reaction to exposure or ingestion of finfish. The risk of cross-contamination between fish and shellfish is very high in restaurants and packing companies, and many people with a shellfish allergy are also allergic to one or more types of fish; in general, people with a shellfish allergy are advised to avoid all fish and seafood.

Types of Shellfish

There are two types of shellfish: crustaceans (such as crab, lobster, shrimp and crawfish), and mollusks (such as oyster, clam and mussels). Many people with a shellfish allergy can safely consume mollusks without having a reaction. Some people, however, can have strong reactions to both crustaceans and mollusks, so it is best to consult an allergist or healthcare professional to be sure which foods are safe to eat. Fortunately, as one of the top eight food allergens, shellfish is covered under the Food Allergen Labeling and Consumer Protection Act (FALCPA), so manufacturers must label the presence of all shellfish in their food items. In general, people with a shellfish allergy are advised to avoid the following foods:

• All types of crab
• Lobster
• Shrimp
• Prawns
• Crawfish
• Cuttlefish
• All types of clams
• Scallops
• Squid
• Octopus (taco)
• Snails (escargot)
• Mussels

Shellfish are rarely a hidden ingredient, and most companies will clearly label this allergen on their packages. However, shellfish can sometimes be found in unexpected places, and it’s important to be aware of potential dangers in items such as:

• Glucosamine supplements
• Soup stock
• Fish stock
• Artificial fish
• Bouillabaisse
• Dishes containing fish sauce, such as curry

The allergenic proteins in shellfish are sometimes released into the air during food preparation and cooking, so it is advised that children and adults with severe shellfish allergies avoid cooking areas and surfaces where shellfish may be present. This includes seafood restaurants and many restaurants serving Asian cuisine where seafood shares cooking surfaces with other foods.

Like other food allergies, there is no cure for a shellfish allergy, and once developed, people rarely are able to outgrow this particular condition. Antihistamines may be prescribed to treat symptoms that may arise from exposure, and in the case of an anaphylactic reaction, an epinephrine shot must be administered immediately. If you or your child notices a reaction from exposure to shellfish, it is important to get checked out right away. The best medicine, as always, is a proper diagnosis and strict avoidance of the allergen. Through careful planning and plenty of medical and community support, it is certainly possible for children with shellfish allergies to lead healthy and fulfilling lives.

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