Allergic Rhinitis and Sublingual Immunotherapy

Sublingual immunotherapy (SLIT) is an alternative to conventional immunotherapy (also known as allergy shots). SLIT involves using allergenic substances placed under the tongue. One advantage of SLIT over allergy shots is that SLIT does not involve needles; this makes it less unpleasant and a treatment that can be done at home rather than at a doctor’s office.

Research supporting the use of SLIT for allergic rhinitis is promising. One study suggests that SLIT is not only effective for treating allergies, but may also help prevent the development of new allergies or mild persistent asthma in children with allergic rhinitis or intermittent asthma.⁷⁰

A similar but less widely accepted treatment for allergic rhinitis is enzyme potentiated desensitization (EPD).

The immune system has many components, and only one of them, the IgE/eosinophil system, produces typical allergic reactions. The intended effect of SLIT is to “train” other branches of the immune system to neutralize allergens before the IgE/eosinophil system "notices" that they are there and causes an allergic reaction.

Read more details about Sublingual Immunotherapy.

Numerous double-blind, placebo-controlled studies indicate that SLIT can improve all major symptoms of allergic rhinitis when the offending allergens are known.^{32,43,48,49,51,63,68,69} However, in a 2008 comprehensive review of evidence for using SLIT for grass pollen and house dust mite allergies, researchers raised questions regarding the quality and consistency of these and other studies.⁶⁵

SLIT may help prevent the development of new allergies or mild persistent asthma in children with allergic rhinitis or intermittent asthma.⁷⁰

It appears that SLIT may work best if used year round, and year-after-year. SLIT treatment may take 2-3 years to provide a significant benefit.⁵⁴ One placebo-controlled study found that 3 years of treatment was more effective than 2 years.⁵⁶ In addition, to provide benefits for grass allergy season, SLIT must be started at least 8 weeks prior to the onset of the grass allergy season; starting even earlier leads to even better results.⁵⁸

Until approximately the year 2000, SLIT was most commonly offered by practitioners who identified themselves as holistic or alternative. Mainstream medicine regarded SLIT with a lot of skepticism. In recent years, however, numerous well-designed studies of SLIT have been reported, causing the method to gain increasing acceptance among conventional allergists.

Safety Issues

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.^{1 2} In one study, 12% of patients with allergic rhinitis and/or asthma experienced worsening of symptoms at some point in their treatment. ³ Severe allergic reactions appear to occur rarely. However, it has not been tested in high-risk asthma patients. ⁴ Another problem is that no allergy extracts for use in sublingual immunotherapy have been officially approved for use in the US, and therefore products available remain incompletely regulated.

32. Wilson DR, Torres LI, Durham SR. Sublingual immunotherapy for allergic rhinitis. Cochrane Database Syst Rev. 2003;CD002893.
43. Smith H, White P, Annila I, et al. Randomized controlled trial of high-dose sublingual immunotherapy to treat seasonal allergic rhinitis. J Allergy Clin Immunol. 2004;114:831-837.
48. Penagos M, Compalati E, Tarantini F, et al. Efficacy of sublingual immunotherapy in the treatment of allergic rhinitis in pediatric patients 3 to 18 years of age: a meta-analysis of randomized, placebo-controlled, double-blind trials. Ann Allergy Asthma Immunol. 2006;97:141-148.
49. Cox LS, Linnemann DL, Nolte H, et al. Sublingual immunotherapy: a comprehensive review. J Allergy Clin Immunol. 2006;117:1021-35.
51. 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]
54. Worm M. Efficacy and tolerability of high dose sublingual immunotherapy in patients with rhinoconjunctivitis. Allerg Immunol (Paris). 2006;38:355-360.
56. Tahamiler R, Saritzali G, Canakcioglu S. Long-term efficacy of sublingual immunotherapy in patients with perennial rhinitis. Laryngoscope. 2007;117:965-969.
58. Calderon MA, Birk AO, Andersen JS, et al. Prolonged preseasonal treatment phase with Grazax sublingual immunotherapy increases clinical efficacy. Allergy. 2007;62:958-961.
63. 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.
65. 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.
68. 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.
69. 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.e2.
70. Marogna M, Tomassetti D, Bernasconi A, et al. Preventive effects of sublingual immunotherapy in childhood: an open randomized controlled study. Ann Allergy Asthma Immunol. 2008;101:206-211.