Food allergy has become an increasingly prevalent international health problem. Allergic reactions can result in life-threatening anaphylaxis in a short period of time, so the current standard of care dictates strict avoidance of suspected trigger foods and accessibility to injectable epinephrine. Intervention at the time of exposure is considered a rescue therapy rather than a disease-modifying treatment. Investigators have been studying allergen immunotherapy to promote induction of oral tolerance. This article examines the mechanisms of oral tolerance and the breakdown that leads to food allergy, as well as the history and current state of oral and sublingual immunotherapy development.