Due to the heterogeneity of the disease and its many subtypes, guidelines for diagnosis can only cover a routine programme, including a thorough history and physical examination as well as specific provocation and laboratory tests on the basis of the suspected cause.
Of all diagnostic procedures, a thorough history including all possible eliciting factors and significant aspects as to the nature of the urticaria is of paramount importance. The questions that should be asked include the following items:
- time of onset of disease;
- frequency and duration of whealing;
- diurnal variation;
- shape, size, and distribution of wheals;
- associated angiedema;
- associated subjective symptoms of lesion, e.g., itch, pain;
- family history regarding urticaria, atopy;
- previous or currently existing allergies, infections, internal diseases, or other possible causes;
- induction by physical agents or exercise;
- use of drugs (NSAID, injections, immunizations, hormones, laxatives, supposatories, ear and eye drops, and alternative remedies);
- smoking habits;
- type of work;
- occurrence in relation to weekends, holidays and foreign travel;
- surgical implantations;
- reactions to insect stings;
- relationship to the menstrual cycle;
- response to therapy;
- quality of life related to urticaria.
The second step is the physical examination of the patient. This should include a test for dermographism when the patient has ceased antihistamine therapy for at least two days Subsequent diagnostics steps depend on the nature of the urticaria subtype.