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Prevention
By Mayo Clinic staffIf you know you're allergic to shellfish, the only sure way to avoid an allergic reaction is to avoid all shellfish or products that might contain shellfish. Even trace amounts of shellfish can cause a severe reaction in some people. Shellfish isn't usually a hidden food ingredient, so it may be easier to avoid than some other allergy-causing foods.
Avoiding shellfish
- Be cautious when dining out. Eating at restaurants poses the biggest danger of mistakenly eating shellfish. When you eat at restaurants, always check to make sure the same pan, oil or utensils used for shellfish are not also used to prepare other foods. This is called cross-contamination.
- Use extra caution at seafood restaurants. Fish and shellfish are biologically distinct, so fish will not cause an allergic reaction if you have a shellfish allergy — unless you are also allergic to fish. But when eating at a seafood restaurant, there is a higher risk of cross-contamination of your food with trace amounts of shellfish. Some people even have allergic reactions to cooking vapors.
- Read labels. Cross-contamination can occur in stores where food may be processed or displayed along with shellfish. It also can occur during manufacturing. Be sure to read food labels carefully. Companies are required to clearly label any product that contains even small amounts of shellfish or other foods that often cause allergic reactions.
- Keep your distance. You may need to completely avoid environments where shellfish are prepared or processed. Some people even have a reaction after touching shellfish or inhaling steam from cooking shellfish.
Some people mistakenly believe that allergy to iodine or allergy to radiocontrast dye used in some lab procedures can cause reactions in people with a shellfish allergy. Reactions to radiocontrast material or iodine are not related.
Glucosamine, a supplement used to prevent and treat arthritis, is made from crab, lobster or shrimp shells. While it does not appear to cause an allergic reaction in most people who have a shellfish allergy, more studies need to be done to determine whether it is safe for people allergic to shellfish.
If you are at risk of a serious allergic reaction, talk with your doctor about carrying emergency epinephrine (adrenaline). If you've already had a severe reaction, wear a medical alert bracelet or necklace that lets others know that you have a food allergy.
- Lopata AL, et al. Shellfish allergy. Clinical & Experimental Allergy. 2010;40: 850.
- Lopata AL, et al. New insights into seafood allergy. Current Opinion in Allergy and Clinical Immunology. 2009;9:270.
- Sicherer SH. Seafood allergies: Fish and shellfish. http://www.uptodate.com/home/index.html. Accessed April 5, 2011.
- Atopic and allergic disorders. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merckmanuals.com/professional/sec13/ch165/ch165c.html?qt=seadfood%20allergy&alt=sh. Accessed April 8, 2011.
- Seafood allergy. American Academy of Allergy, Asthma & Immunology. http://www.aaaai.org/patients/advocate/2006/winter/seafood.asp. Accessed April 8, 2011.
- Kurowski K, et al. Food allergies: Detection and management. American Family Physician. 2008;77:1678.
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