Sublingual Immunotherapy (SLIT): The Scientific Facts and Comparison with Allergy Shots/Injections

1. Is sublingual Immunotherapy (SLIT) as effective as subcutaneous injection immunotherapy (SCIT) ie. Allergy shots?

Comparison of SLIT and SCIT reveal both give significant reductions of both allergic symptoms and allergy medication usage (1). Another study compared SLIT and SCIT in patients with nasal allergies with and without asthma. The study found that both therapies were equally effective (2).

2. Sublingual Immunotherapy is much safer than subcutaneous injection immunotherapy in clinical studies.

In a comprehensive review of 104 articles on SLIT (3), there were 66 studies that provided some information on safety and tolerance, representing 4,378 patients who got nearly 1.2 million total doses. There were no fatalities or anaphylactic events reported, and only 1.4 significant adverse events per 100,000 SLIT doses. By comparison, according to the World Allergy Organization, there are an estimated 3.4 fatal and 22.8 near-fatal reactions caused by subcutaneous allergy shots every year.

3. How Effective is Sublingual Immunotherapy (SLIT)?

A review paper for allergic rhinitis included 22 clinical trials and nearly 1,000 patients and showed significant reduction in both symptoms and allergy medication usage (4). A review paper for asthma which included 25 clinical trials and over 1,000 patients, indicated that it is beneficial. The authors noted that SLIT is a safe alternative to subcutaneous injections and that it gives improvements in symptoms, medication use, pulmonary (lung) function, and overall well-being (5).

A review paper for allergic rhinitis in children, which included 10 clinical trials and 484 patients, showed that SLIT is effective compared to placebo (6). In another review of 9 clinical trials representing 441 children with asthma showed that SLIT reduced symptom scores and rescue drug use in kids (7).

Lastly 56 children were enrolled in a double blind placebo trial with atopic dermatitis with mite sensitivity. The authors concluded that SLIT therapy to dust mite improves mild to moderate atopic dermatitis (8).


Sublingual Immunotherapy (SLIT) Fact Sheet Scientific References

1. Quirino T, Iemoli E, Siciliani E, Parmiani S, Milazzo F. Sublingual vs injective immunotherapy in grass pollen allergic patients: a double-blind double-dummy study. Clin Exp Allergy. 1996;26 : 1253

2. Saporta, D. Efficacy of Sublingual Immunotherapy versus Subcutaneous Injection Immunotherapy in Allergic Patients. J of Environmental and Public Health.2012; Article ID 492405, 6 pg.

3. Cox LS, Larenas-Linnemann D, Nolte H, Weldon D, Finegold I, Nelson HS. Sublingual immunotherapy: a comprehensive review. J Allergy Clin Immunol.2006; 117:1021-1035.

4. Wilson DR, Torres L, Durham SR. Sublingual immunotherapy for allergic rhinitis. Allergy. 2005;60:3– 8.

5. Calamita Z, Saconato H, Bronhara Pela` A, Nagib Atallah A. Efficacy of Sublingual Immunotherapy in asthma. Systematic review of randomized clinical trials. Allergy. 2006;61:1162–1172.

6. Penagos M, Compalati E, Tarantini F, Baena-Cagnani R, Huerta J, et al. Efficacy of sublingual immunotherapy in the treatment of allergic rhinitis in children. Meta analysis of randomized controlled trials. Ann Allergy Asthma Immunol. 2006;97:141–148.

7. Penagos M, Passalacqua G, Compalati E, Baena-Cagnani CE, Orozco S, et al. Metaanalysis of the efficacy of sublingual immunotherapy in the treatment of allergic asthma in pediatric patients, 3 to 18 years of age. Chest. 2008;133:599–609.

8. Pajno, GB., Caminiti, L., Vita, D., etc al. Sublingual immunotherapy in mite-sensitized children with atopic dermatitis: A randomized, double-blind, placebo-controlled study. American academy of Allergy, Asthma, and Immunology. Doi:10.1016/j.jaci.2007.04.008.


  1. I had a secondary gastric BPD bypass on 11/13/2015, after having Roux-N-Y on 1/12/2006.

    The most recent By Pass has had some very dramatic side affects, that appear to be nutritionally based. Is there anyway you can help someone from several states (geographically) away?

    • Dr.Williamson says:

      I would recommend seeking a doctor who does Nutrient IVs in your area. No matter how many vitamins you take orally, your absorption is limited due to the Gastric Bypass Surgery. Taking sublingual versions of vitamins will also help but you will not be able to get all of your nutrients this way. The best way to keep your nutrients replenished is to have a nutritional IV on a regular basis.

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