Adverse reactions to foods are frequent in everyday life. They are divided into toxic and immunologic food reactions. The awareness of toxic food reactions among adverse reactions to food is essential for correct diagnosis. Enzymatic food intolerance, adverse reactions to food or food additives, pharmacologic food intolerance, psychosomatic factors, food allergy with classic symptoms (anaphylaxis, urticaria-angioedema), atopic dermatitis, contact dermatitis (protein), upper and lower respiratory symptoms like rhinitis or asthma, and gastrointestinal disorders (oral allergy syndrome, colic, nausea, vomiting, diarrhea, abdominal pain) are discussed. Target organs throughout the body-ear, eye, pharynx, skin, lung, joints, and muscles-can be involved. The gold standard in diagnosis is a double-blind, placebo-controlled food challenge test. The diagnostic tools available for most food-related disorders are the skin-prick test and radioallergosorbent test. The treatment of food-induced urticaria consists of elimination of the offending food or substance from the diet, use of antihistamines, and immunotherapy.