To assess the effect and safety of sublingual Dermatophagoides Farinae Drops in adult patients with atopic dermatitis and allergic sensitization to house dust mites.240 adults age 18 to 60 years with atopic dermatitis(Objective Scoring Atopic Dermatitis, Objective SCORAD from 10 to 40) are going to be enrolled in a randomized,double-blind,placebo-controlled study.Sublingual Dermatophagoides Farinae Drops or placebo is given for 9 months in addition to standard therapy.SCORAD,average anesis interval,rescue medicine and DLQI will be recorded.

SCORAD is composed of skin rash area,severity and subjective symptom including pruritus and sleeping quality.Skin rash area and severity score are objective SCORAD(range from 0 to 83).Subjective SCORAD range from 0 to 20 and total SCORAD range from 0 to 103.

Inclusion Criteria:

• Patients of either sex ,aged from 18 to 60 years. Diagnosed of atopic dermatitis.
• Mild to moderate AD ( [SCORAD] 1O-40)
• The results of skin prick tests with dermatophagoides farinae allergen extracts preparation is positive(≥2+)
• Written informed consent by the subject or legal guardian.
• Female patients of child-bearing potential must be negative pregnant test on screening and use an appropriate method of contraception.

Exclusion Criteria:

• Dust mites are not the primary allergens.
• Pregnant, breastfeeding women or women planned to pregnant within 1 year.
• Have concurrent skin disease that it could interfere with the study evaluation.
• Were treated with antihistamines or topical therapy within 7 days of randomization.
• Have received systemic corticosteroids,leukotriene receptor antagonists or immunosuppressants within 4 weeks of randomization.
• Have received phototherapy (e.g. UVA, UVB) within 4 weeks of randomization.
• Have a history of immune suppressed diseases(malignant tumor or infection of HIV), autoimmune disease or tuberculosis.
• Patients with impaired liver function (aspartate aminotransferase and/ or alanine aminotransferase levels 1.5 times the upper limit of normal), impaired renal function(serum creatinine>normal value) or other severe diseases.
• Bronchial asthma patients who need treatments with corticosteroids and or β agonists(including injection, oral administration or inhalation) regularly.
• Patients who need to take β-blockers during research.
• Have received investigational drugs within 3 months prior to randomization or planned use of other investigational drugs during participation in this study.
• Have received immunotherapy with dust mite preparation within 3 years prior to randomization.
• Patients with severe mental disorders.