Subcutaneous and sublingual immunotherapy for allergic rhinitis: What is the evidence?

BACKGROUND Increasing interest in sublingual immunotherapy (SLIT) among practitioners and patients has resulted in numerous publications and clinical trials in recent years. With the clinical growth of SLIT, discussions of its efficacy, safety, and immunologic effects have intensified, as have comparisons to subcutaneous immunotherapy (SCIT). In the United States, SCIT has been the traditional form of immunotherapy for inhalant allergy and is the only immunotherapy method approved by the U.S. Food and Drug Administration at this time. The similarities and differences between SLIT and SCIT are often discussed, yet clinical studies directly comparing these immunotherapy methods are scarce. METHODS A literature review of specific issues and controversies between SLIT and SCIT for allergic rhinitis was conducted. RESULTS Safety, efficacy, and immunologic effects of these two immunotherapy techniques are reviewed. CONCLUSION Unanswered questions relating to SLIT are examined.