A daily dose of allergens under the tongue appears to be effective in desensitizing patients with allergic rhinitis or asthma to respiratory allergens.
In a recent review article, researchers found moderate evidence supporting the efficacy of sublingual therapy. In 8 of 13 studies they evaluated, patients with asthma who were treated with this approach had a 40% or greater improvement in symptoms compared with a control or alternate therapy group. Evidence of efficacy for allergic rhinitis was moderate: 9 of 36 studies showed a 40% or more improvement in symptoms. Although common in Europe, sublingual therapy isn't approved by the US Food and Drug Administration.
Selections From News@JAMA and JAMA Forum. JAMA. 2013;309(19):1983. doi:10.1001/jama.2013.5120