Sublingual immunotherapy (SLIT) is a method of treating allergies that closely resembles conventional "allergy shots." In both of these methods, small amounts of allergenic substances are administered periodically and over a long period of time, via a route different from that in which the body ordinarily encounters them. For example, plant pollens ordinarily cause their allergic reactions by being inhaled. With allergy shots, pollen extracts are injected under the skin, while in SLIT, they are placed under the tongue. The immune system has many components, and only one of them, the IgE/eosinophil system, produces typical allergic reactions. The intended effect of these alternate routes of administration is to “train” other branches of the immune system to neutralize allergens before the IgE/eosinophil system even (so to speak) notices that they are there.
The great potential advantage of SLIT over allergy shots is that SLIT does not involve needles; this makes it less unpleasant and also capable of being done at home rather than at a doctor’s office. The absence of needles may also explain why SLIT has long been categorized as a form of alternative rather than conventional medicine.
There are no universally accepted criteria by which a treatment is classified as part of "alternative" rather than conventional medicine. Some treatments, such as acupuncture
Sublingual immunotherapy (SLIT) falls primarily in the last camp. Until approximately the year 2000, SLIT was most commonly the province of practitioners who identified themselves as holistic or alternative, and it was looked on with skepticism by mainstream medicine. In recent years, however, numerous well-designed studies of SLIT have been reported, causing the method to gain increasing acceptance among conventional allergists.
What Is the Scientific Evidence for Sublingual Immunotherapy?
Perhaps the best evidence for the effectiveness of SLIT involves treatment of allergic rhinitis
For example, in a double-blind study of 855 adults with grass allergies, SLIT using grass pollen tablets for approximately 18 weeks markedly reduced allergy symptoms,
However, in a 2008 comprehensive review of studies investigating SLIT for grass pollen and house dust mite allergies, researchers were unable to substantiate claims of effectiveness, largely because of the variable quality of the studies they uncovered.
Unfortunately, as with conventional allergy shots for hay fever, it appears that if SLIT is in fact effective, it must be used for a long time for best results. Three years of treatment may be better than two, and two years better than one.
One study suggests that SLIT is not only effective for treating allergy, but may be useful in preventing the development of new allergies or mild persistent asthma in children with allergic rhinitis or intermittent asthma.
SLIT appears to be safer than conventional allergy shots. The most frequent report of adverse effects include oral itching or swelling, as well as gastrointestinal upset; in the great majority of cases, these are mild and short-lived. 11-13
1. Durham SR, Yang WH, Pedersen MR, et al. Sublingual immunotherapy with once-daily grass allergen tablets: a randomized controlled trial in seasonal allergic rhinoconjunctivitis. J Allergy Clin Immunol. 2006;117:802-809.
8. Marogna M, Spadolini I, Massolo A, et al. Clinical, functional, and immunologic effects of sublingual immunotherapy in birch pollinosis: a 3-year randomized controlled study. J Allergy Clin Immunol. 2005;115:1184-1188.
9. Bernardini R, Campodonico P, Burastero S, et al. Sublingual immunotherapy with a latex extract in paediatric patients: a double-blind, placebo-controlled study. Curr Med Res Opin . 2006;22:1515-1522.
10. Niu CK, Chen WY, Huang JL, et al. Efficacy of sublingual immunotherapy with high-dose mite extracts in asthma: a multi-center, double-blind, randomized, and placebo-controlled study in Taiwan. Respir Med . 2006;100:1374-1383.
13. Malling HJ, Lund L, Ipsen H, et al. Safety and immunological changes during sublingual immunotherapy with standardized quality grass allergen tablets. J Investig Allergol Clin Immunol . 2006;16:162-168.
14. Rak S, Yang WH, Pedersen MR, et al. Once-daily sublingual allergen-specific immunotherapy improves quality of life in patients with grass pollen-induced allergic rhinoconjunctivitis: A double-blind, randomised study. Qual Life Res . 2006 Oct 11. [Epub ahead of print]
16. Nettis E, Colanardi MC, Soccio AL, et al. Double-blind, placebo-controlled study of sublingual immunotherapy in patients with latex-induced urticaria: a 12-month study. Br J Dermatol. 2007;156:674-681.
19. Mosges R, Bruning H, Hessler HJ, et al. Sublingual immunotherapy in pollen-induced seasonal rhinitis and conjunctivitis: a randomized controlled trial. Acta Dermatovenerol Alp Panonica Adriat. 2007;16:143-148.
20. Hoeks SB, de Groot H, Hoekstra MO. Sublingual immunotherapy in children with asthma or rhinoconjunctivitis: not enough evidence because of poor quality of the studies; a systematic review of literature. Ned Tijdschr Geneeskd. 2008;152:261-268.
21. Pfaar O, Klimek L. Efficacy and safety of specific immunotherapy with a high-dose sublingual grass pollen preparation: a double-blind, placebo-controlled trial. Ann Allergy Asthma Immunol. 2008;100:256-263.
22. Dahl R, Kapp A, Colombo G, et al. Sublingual grass allergen tablet immunotherapy provides sustained clinical benefit with progressive immunologic changes over 2 years. J Allergy Clin Immunol. 2008;121:512-518.
24. Rodriguez-Perez N, Ambriz-Moreno Mde J, Canonica GW, et al. Frequency of acute systemic reactions in patients with allergic rhinitis and asthma treated with sublingual immunotherapy. Ann Allergy Asthma Immunol. 2008;101:304-310.
Last reviewed April 2009 by EBSCO CAM Review Board
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