Shellfish allergies are among the most common food allergies in adults worldwide, affecting up to 3% of the global population. Reactions to shellfish can be quite severe and include symptoms such as hives, vomiting, swelling, and, in some cases, life-threatening anaphylaxis. Unlike many other food allergies, shellfish allergies are rarely outgrown and often persist throughout life. Crustaceans—such as shrimp, crab, and lobster—are the most frequent triggers of severe reactions, though some people also react to mollusks like clams, mussels, and oysters. Given the potential severity and lifelong nature of shellfish allergies, those affected often need to carry emergency medications, such as epinephrine, and must be particularly vigilant about cross-contamination risks, especially when dining in seafood restaurants.