In the last years an increase of allergic diseases has been observed whose prevalence is about 20-30% in general population of western countries. However there is a risk of an over diagnosis of allergic diseases as many different diseases (migraine, chronic urticaria, chronic inflammatory bowel diseases, chronic-fatigue syndrome etc.) are considered due to food allergy or intolerance. In many patients the diagnosis is based on the results of alternative diagnostic tests such as the cytotoxic test, the provocation/neutralization sublingual or subcutaneous test, the heart-ear reflex test, the kinesiology, the biorisonance, the electro-acupuncture, and the hair analysis, or on immunological tests (immunocomplex or specific food IgG). We reviewed the scientific evidences of these tests (specificity, sensibility, rationale, reproducibility). According to most studies none of them had to be recommended as useful for the diagnosis of food allergy or intolerance. Physicians should alert patients about the risk of an indiscriminate use of these test in the diagnosis of food allergy. In fact the use of an incorrect diet could be dangerous, particularly in childhood, as recently shown.