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Suspcious of Seafood Allergies? We Can Help

Shellfish Allergy Symptoms, Causes, and When to See a Doctor in New Orleans

Dr. Reena Mehta is a board-certified allergist that can help you identify and navigate shellfish allergies in New Orleans, LA.

“Dr. Mehta has a great bedside manner and is great with our daughter. She helped us navigate the most up to date treatment options for food allergies in our 9 month old and dedicated one on one attention to us that went above and beyond the norm. She is professional and kind and has a genuine care for her patients. Highly recommend!“

– Parker Valergo, 2019

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Shellfish allergy doctor Dr. Reena Mehta in New Orleans, LA

Shellfish Allergy Overview

Overview

Symptoms

Allergy List

Testing

Myths

Shellfish allergy is a type of seafood allergy. It occurs when the body produces an immunological response to tropomyosin and other muscle proteins found in shellfish. Shrimp, crab, and lobster are crustacea, and they cause most shellfish reactions. Mollusks such as clams, mussels, oysters, and scallops can also cause shellfish allergy, but allergies to mollusks are less prevalent compared to allergies to crustacea.

Shellfish allergy is an immunoglobulin E (IgE) antibody-mediated allergy. This means that when you ingest shellfish, your immune system overreacts by producing IgE antibodies which bind to mast cells. Once the shellfish protein allergen binds to the IgE antibody on the mast cell, the mast cell will release histamines that trigger allergy symptoms.

Shellfish allergies in New Orleans caused by crab legs

Shellfish allergy is different from fish allergy. You could be allergic to shellfish but not finned fish with a backbone such as salmon, trout, halibut, cod, or tuna. In contrast to a lot of allergies, most people develop shellfish allergies when they are adults, and shellfish allergies typically last for life.

Shellfish Allergy Symptoms

Shellfish allergy that is IgE-mediated can cause a variety of symptoms which usually appear within minutes to an hour of ingestion. Shellfish allergy symptoms include:

Urticaria (hives), an itchy skin rash of raised red spots
Angioedema, or swelling under the skin
Anaphylaxis, which is when multiple body systems produce a significant immune response causing a rapid drop in blood pressure and possible circulatory shock that is life-threatening
GI symptoms such as nausea, vomiting, cramping, and diarrhea
Lightheadedness and fainting

Shellfish asthmatic reactions can occur. For example, when exposed to an environment where shellfish is cooking or being processed, vapors from the shellfish may induce asthma.

Itchy hives caused by allergic reaction to shellfish

In addition, shellfish allergy symptoms can be triggered by exercise or exertion following ingestion. However, in the absence of intense physical activity, a person might be able to eat shellfish without any reaction.

Shellfish Allergy List

Many foods contain shellfish products that can trigger and cause an allergic response, some of which are especially popular here in New Orleans. Below is a list of foods that contain shellfish:

Calamari and squid
Clam chowder
Lobster bisque
Crab dip and crab cakes
Imitation crab meat
Crawfish boil
Creole or Cajun gumbo
Jambalaya
Oyster sauce found in Asian cuisine
Prawns
Cocktail shrimp and shrimp scampi
Scallops
Oysters
Clams
Mussels
Escargot
Sushi
Fish oil supplements (may contain trace amounts of shellfish proteins)

Shellfish allergies in New Orleans caused by seafood jambalaya

Shellfish Allergy Tests

Skin & Blood Tests

Your allergist may perform a skin-prick test to evaluate for potential shellfish allergy. Small volumes of food allergens (and controls) are pushed into your skin with a sterile needle. After 20 minutes, the skin is re-examined for any wheals, rashes, or bumps. The size of the wheals will indicate the severity of the allergic reaction. It is important to note that skin testing for crustacean seafood (shrimp, crab, lobster, etc.) may be falsely positive due to sensitization to arthropods like dust mites, spiders, and cockroaches.

A blood test can measure the amount of IgE antibody circulating in the blood in reaction to the shellfish allergen versus other types of allergens. High levels of circulating IgE can indicate allergic reaction.

Elimination Diet and Oral Food Challenge

To diagnose a food allergy, your allergist may ask you to temporarily eliminate specific foods that are suspected allergens from your diet for 2 to 4 weeks. If your allergic symptoms disappear during this time, then one or more of the eliminated foods was the allergen. If shellfish allergy is suspected, your allergist may ask you to consume a small amount of shellfish allergen in a supervised, medical setting. This is done to confirm an allergy or to verify you have outgrown one.

Myths About Shellfish Allergies

Shellfish Allergy and Iodine

Patients with shellfish allergies do not have an increased risk of allergic reaction to iodine, which is commonly used as an intravenous contrast agent or dye for medical imaging procedures. Shellfish do contain iodine, but it is the tropomyosin and other muscle proteins in shellfish that cause allergies.

Glucosamine and Shellfish Allergy

Glucosamine supplements are taken for joint health and to prevent osteoarthritis. Some glucosamine products are made from the shells of shellfish. If there is no cross contamination and the product is of high purity, it is unlikely that the shells used in glucosamine supplements contain the shellfish protein allergens that caused a reaction. If you’re unsure about a specific glucosamine supplement, your allergist can help you determine if it’s safe to take.

Shellfish Allergy and Collagen

Fish collagen, derived from the skin, scales, muscle, and bones of fish, is found in some nutritional supplements. Fish collagen supplements do not contain shellfish protein allergens and are unlikely to cause an allergic reaction. However, some supplements contain ingredients collectively referred to as “marine collagen,” which can be sourced from a variety of seafood, both fish and shellfish. Therefore, if you have a shellfish allergy, always read the labels on supplement bottles to verify if any of the ingredients came from the skin or muscle of shellfish, and consult your allergist if you’re unsure.

See a Shellfish Allergy Doctor in New Orleans

Suspicious of shellfish allergy or asthmatic reactions? We can help. Allergist Doctor Mehta has a reputation for developing strong relationships with her patients and being exceptionally attentive to their needs and concerns.

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