Food allergy is a chronic disease that is increasing all over the world, and it can even lead to a loss of life. To prevent any incidents resulting from food allergies, most countries keep strengthening their food allergen labeling requirements domestically and internationally, with a constant monitoring system against undeclared allergens and recall of offending products. In order to avoid economic losses to industry and damages to international relations from undeclared allergens, it is necessary to confirm each country’s regulatory policy on food allergen labeling prior to exportation. Another required action is to try for a reduction of the cross-contamination risk of the allergens during manufacturing and storage, which should be verified by using an accurate and reliable analysis of food allergens. This paper is intended to provide an introduction to the regulation of food allergen labeling by country, allergen management methods to avoid cross-contamination, and allergen detection methods using ELISA, PCR, and LC/ MS. Changes of allergenicity during thermal or nonthermal processing also will be investigated in our review. This review will be helpful for the food industry to better understand patients suffering from food allergies and to manage food allergens in food manufacturing.