Four concentrations of Dermatophagoides pteronyssinus and Dermatophagoides farinae allergen extracts, together with a positive and negative control, using 10 mg/ml histamine dihydrochloride solution and a glycerinated phenol saline solution, respectively, will be tested in every patient in duplicate on the volar surface of the forearm..

This is an open, unblinded and non-randomized biological assay. The study design is a slight modification of the recommendations proposed by the Nordic Guidelines.

Inclusion Criteria:

• Clinical history positive inhalation allergy (rhinitis I rhinoconjunctivitis I asthma) against Dermatophagoides pteronyssinus or Dermatophagoides farinae.
• A prick-test positive (average of the papule ≥ 3 mm diameter) with a summary of the same allergen I presence against the allergen specific Immunoglobulin E.
• The average area of the papule obtained by histamine dihydrochloride to 10 mgml must be greater than or equal 7 mm2.
• Age: over 18 years of age.
• Both sexes.

Exclusion Criteria:

• Subjects outside of the age range.
• Individuals who have previously received immunotherapy in the last 5 years for the treatment of asthma or the allergic rhinoconjunctivitis induced by allergens that may interfere with the extract mixture of Dermatophagoides pteronyssinus or farinae.
• Subjects with important symptoms of rhinoconjunctivitis I bronchial asthma in which the suspension of the antihistamine treatment for systemic is contraindicated.
• Subjects that have previously submitted a serious secondary reaction during skin prick test diagnostic tests.
• Subjects in treatment with ss-blockers.
• Unstable subjects of clinical point of view (asthma acute, febrile, etc.).
• Subjects with lesions of active hives, severe active dermographism, severe atopic dermatitis, sunburn, eczema, lesions of psoriasis in the area of realization of the prick test (risk of false positives).
• Subjects with viral infection activates the herpes simplex or herpes varicella-zoster in the area of realization of the prick test.
• Subjects that have some pathology in which the administration of adrenaline (hyperthyroidism, hypertension, heart disease, etc.) is contraindicated.
• States of the subject that can not offer cooperation and severe psychiatric disorders.
• Pregnant or women at risk of pregnancy and breastfeeding women.