Probability of Having a Shellfish Allergy

Shellfish allergy is the most common food allergy in American adults, affecting approximately 2.5% of the adult population (about 6.5 million people). Unlike many childhood food allergies, shellfish allergy typically develops in adulthood and is rarely outgrown. It can appear at any age, even in people who have previously eaten shellfish without problems.

Shellfish allergy is divided into two categories: crustacean shellfish (shrimp, crab, lobster) and mollusk shellfish (clams, mussels, oysters, scallops). Most people with shellfish allergy react to crustaceans, but cross-reactivity between the two groups is possible. The primary allergen is tropomyosin, a muscle protein found in all shellfish.

Reactions range from mild urticaria (hives) and oral allergy symptoms to severe anaphylaxis. Shellfish is the leading trigger of food-induced anaphylaxis in adults. Because cooking does not destroy shellfish allergens, avoidance is the only reliable prevention. Cross-contamination in restaurants is a significant risk, as shellfish proteins can become airborne during cooking. People with shellfish allergy should carry epinephrine auto-injectors and wear medical identification.