Food allergies are common and affect up to 10% of infants in some countries. Oral ingestion of certain nutrients may cause adverse reactions such as urticaria and anaphylaxis. Substances (biological, chemical, or physical) that can cause reactions in sensitive people are called food allergens. Many factors affect the type and severity of the reaction, such as the type and amount of the allergen, the way it enters the body, and the personal hypersensitivity level. Food allergy is a growing health problem affecting a significant number of people worldwide. Food allergy is increasing markedly in prevalence in both western and developing countries. Various chemicals in foods are common in all food groups, and it is extremely difficult to implement multiple diets to avoid these chemicals. It is also important to acknowledge the lack of rigorous research on food allergy-like symptoms caused by chemicals. To accurately detect such diseases, objective methods need to be investigated in more detail and standardized. Healthcare professionals need to distinguish food allergies from allergy-like toxic reactions.