Many studies have assessed the efficacy of SCIT in asthma over the past 50 years. A recently published Cochrane review meta-analysis of SCIT assessed 88 studies on 3,459 subjects with asthma and included 42 trials for dust mites, 27 for pollen, 10 for animal dander, two for molds, two for latex, and six for multiple allergens. Given the intrinsic nature of such studies and this expanded time frame, there was significant heterogeneity among the various comparisons between the studies, and only 16 trials had clear evidence of allocation concealment. Overall, SIT improved asthma symptoms (standardized mean difference [SMD], −0.59; 95% CI, −0.83 to −0.35), reduced medication use (SMD, −0.53; 95% CI, −0.80 to −0.27), and diminished bronchial hyperresponsiveness (BHR) (SMD, −0.35; 95% CI, −0.59 to −0.11). Statistically, the meta-analysis found that it would require treating three subjects to prevent an exacerbation for one individual, four subjects to improve medication use in one, and four subjects to avoid nonspecific or allergen-specific BHR in one patient, respectively. In general, it was noted that symptom scores were improved more significantly by mite and pollen immunotherapy, whereas allergen-specific BHR was improved by mite, pollen, and animal dander immunotherapy.37 Lung function parameters, however, were not reported in all studies, and improvements in FEV1 or peak expiratory flow (PEF) were not consistently demonstrated by use of SCIT, though a nonsignificant trend toward improvement was observed. Given these variable results, the conclusions from this meta-analysis deserve cautious interpretation and acceptance, as we need to consider many variables, including the allergen used, the outcome assessed, and the characteristics of the patients enrolled.