Most “true” food allergies, including those to seafood, are often lifelong conditions. Seafood allergies trigger a reaction in your body that starts when your immune system mistakenly identifies a protein in shellfish or fish as a threat.
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Your immune system creates a defense in the form of immunoglobulin E (IgE) antibodies that react every time your body detects the protein.
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Crustaceans are one type of shellfish, and include crab, lobster, shrimp, and crayfish. When you have an IgE antibody-triggered allergy to one type of crustacean, you’re likely to be allergic to others and should avoid these as well.
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Mollusks, the other type of shellfish, include clams, oysters, mussels, and scallops. People who get a reaction from a crustacean, such as crab, may be able to eat mollusks, such as oysters, without an issue. Similarly, being allergic to shellfish doesn’t automatically mean you will also get a reaction from eating finned fish because these animals aren’t closely related.
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It’s important to ask your doctor for a list of foods to avoid that are specific to your allergy. They may be able to conduct an allergy test that provides more details about the foods that may cause a reaction.
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Symptoms of a seafood allergy can vary, and while some are mild, others are potentially life-threatening. Signs to watch out for include:
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- Itchy or irritated skin
- Hives
- Swelling of the face, tongue, lips, throat, or other areas of the body
- Nasal stuffiness
- Dizziness, fainting, or lightheadedness
- Coughing and choking, or a tight feeling in the throat
- Wheezing or trouble breathing
- Stomach pain, vomiting, diarrhea, or nausea
In the most severe cases, you may experience a medical emergency known as anaphylaxis, which prompts your immune system to release a large amount of chemicals into your body, possibly resulting in shock. Signs of anaphylaxis include:
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- Swollen throat or tongue
- Tightness in the throat or difficulty breathing
- Symptoms of shock, including a rapid or weak pulse and a severe drop in blood pressure
- Choking, coughing, or wheezing with trouble breathing
- Dizziness, fainting, or lightheadedness
- Severe skin rash, hives, itching, or swelling
- Diarrhea, nausea, or vomiting
Even though some anecdotal stories suggest a shellfish allergy as the cause of joint pain, studies haven’t shown this to be true.
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