This article is intended to review the current literature on "hidden" food allergens and the various ways in which sensitized individuals may be exposed to these allergens. A focus on advances in food labeling, and the Food Allergen Labeling and Consumer Protection Act (FALCPA) is also included, because it assists food-allergic consumers in the strict avoidance of specific foods. Article information was gathered primarily through a computer search of relevant data relating to human subjects. Our findings indicate that sensitized individuals can unknowingly be exposed to allergenic proteins in foods through cross-contact, food containing allergenic nonfood products, food additives, and cross-reactivity. Furthermore, food packaging and formulation errors, ingredient switching, and foods not covered under the FALCPA were also found to be sources of hidden food allergens. There are many ways in which hypersensitive individuals can be exposed to potentially dangerous allergens despite careful avoidance. Furthermore, health care providers should consider various sources of hidden allergens in food-allergic individuals with an unclear etiology. Food hypersensitivity has been identified as a significant medical dilemma in our society. Recent efforts to increase public awareness and strides made in labeling of food products are encouraging.