Primary care physicians will conduct allergy diagnosis based on the history provided by the patient. In case of a possible IgE type allergy, investigations will be made by skin tests or measurement of specific IgE antibodies in the serum. Interpretation of positive tests will have to consider possible sensitizations in absence of allergic symptoms that should not lead to inadequate therapeutic measures or diet. This review will provide to primary care physicians guidance to choose the best method in the appropriate situations for allergy diagnosis.