Sublingual Immunotherapy
What Is Sublingual Immunotherapy (SLIT)?
Sublingual immunotherapy (SLIT) involves placing a food allergen dissolved in a small amount of liquid under the tongue for several minutes before either spitting it out or swallowing it. This method exposes the allergen to immune cells in the mouth lining, which can help build food tolerance. SLIT has been used to treat allergies to foods such as kiwi, peanut, hazelnut, milk, and peach. Although some allergists offer SLIT for food allergies, it is not widely available.
During SLIT treatment, the doses are gradually increased in an escalation phase until a steady daily maintenance dose is achieved. Compared to oral immunotherapy (OIT), SLIT requires smaller doses due to the limited capacity of liquid that can be held under the tongue. The doses in SLIT are typically measured in micrograms or milligrams of protein.
Is SLIT Effective?
A 2019 study conducted by the University of North Carolina (UNC), showed encouraging results for prolonged peanut SLIT treatment. In this study, 48 children aged 1-11 were given peanut SLIT for up to five years. Two-thirds of the participants, and 87 percent of those who underwent three to five years of treatment, were able to tolerate at least 750 mg of peanut protein (about 2.5 peanut kernels).
Another UNC study published in 2021 focused on younger children (aged 1-4 years). It found that 74 percent of the children who received peanut SLIT for 36 months could pass an oral food challenge (OFC), consuming 4,443 mg of peanut protein (equivalent to 15-18 peanut kernels) without any adverse reaction. In contrast, none of the children given a placebo passed the OFC. Three months after stopping the treatment, 63 percent of the children treated with peanut SLIT and 11 percent of those given a placebo passed a second OFC with a cumulative dose of 4,443 mg of peanut protein.
Is SLIT Safe?
In the 2019 UNC study, the most common side effects of peanut SLIT were an itchy mouth and throat, with no reactions requiring epinephrine. Gastrointestinal symptoms led to the withdrawal of two participants (4 percent) from the study.