You might have heard of or have been asked about a new therapy called allergy drops. With no shots, no weekly office visits, and affordability, they sound great. However, allergy drops delivered under the tongue certainly are not a new treatment. They have been used in low doses by alternative practitioners to treat allergy for many years in this country with questionable efficacy. Oral allergy drops in this low dose are felt to be equivalent to placebo.
Allergen immunotherapy delivered by the subcutaneous route (allergy shots) has been shown to be very effective in multiple placebo-controlled trials as well as several
meta-analyses. In addition, it has been shown to induce disease remission, and prevent the onset of new allergies as well as asthma.1
Allergen immunotherapy, regardless of the route of administration, is very dose dependent. Despite the fact that subcutaneous immunotherapy (allergy shots) have been in use since 1911, studies assessing optimal dosing have only been conducted recently. The consensus at this time according to the majority of the worldwide allergy societies is that a dose of 5-20 mcg of major allergen per injection is necessary to achieve efficacy/allergy resolution.1 This dose is relatively high and is occasionally associated with systemic reactions.
Recently, sublingual immunotherapy (SLIT), in controlled studies using high doses of allergen (3-375 times the dose used in subcutaneous immunotherapy) under the tongue followed by spitting or swallowing, has been studied extensively in Europe and has demonstrated some efficacy. 2, 3 However, a number of recent studies also suggest that SLIT may be less effective than allergy shots. 4, 5 It is very important not to confuse low-dose allergy drops under the tongue, which have questionable efficacy, with high-dose sublingual immunotherapy as practiced in Europe, which has demonstrated some potential.
Many other questions regarding SLIT remain unanswered, such as effective dose and schedule, prevention of new allergies and asthma, mechanism, and safety in high-risk groups. At this time, sublingual immunotherapy is not approved by the FDA and is not endorsed by a task force representing the two major allergy societies in the U.S. (ACAAI/AAAAI SLIT Joint Task Force.) Any use of allergen by this route is offlabel. SLIT may also be potentially expensive in light of the high doses of allergen
required as well as the common lack of insurance coverage for this treatment.
We at Boise Valley Allergy and Asthma Clinic are excited about the potential for SLIT but are also cautious because of the unanswered questions and lack of approval by
the FDA and U.S. allergy societies. If and when FDA approval is granted, we will examine any new research as well as the U.S. allergy societies’ recommendations
and make a decision that we feel is in the best interest of our patients.
1. Bousquet, J. et. al. World Health Organization Position Paper: allergen immunotherapy. Therapeutical vaccine for
allergic disease. Allergy 1998;53:1-42.
2. Canonica, G. et. al. Noninjection routes of immunotherapy. J Allergy Clin Immunol 2003;111:437-48.
3. Passalacqua, G. et. al. An update on sublingual immunotherapy. Allergy Clin immunol Int—J World Allergy
4. Nelson, H. et. al. J Allergy Clin Immunol. 1993;92:229-236.
5. Bowen, T. et. al. Ann All Asthma Immun. 2004;93:425-430.