Abstract Guidelines on the treatment of asthma, allergic rhinitis (AR) and allergen immunotherapy (AIT) lack recommendations for house dust mite (HDM) allergy. An expert panel reviewed current guidelines in the light of new data, to assess whether guidelines could be improved. Most guidelines and key position papers did not provide specific recommendations on treatment of allergic asthma (AA) caused by HDM allergy, although some included AIT as a treatment option for AA in general. Around half of the guidelines stated that AIT with HDM extract was an effective treatment for AR, with several indicating sublingual immunotherapy (SLIT) as an option. This heterogeneity is caused by quality issues affecting studies of AIT with perennial allergens in AA and AR, including use of different diagnosis and severity criteria, lack of consistent scoring or grading systems for primary and safety outcomes, and lack of consensus on treatment parameters. There is a need for well-designed clinical trials to serve as a basis for guideline recommendations. Although results from recent studies strengthen the evidence base for the efficacy and safety of SLIT in HDM AA and AR, their impact on subsequent guideline updates will depend on the methodology and evidence model used by each guideline.