Placing small amounts of milk protein under the tongues of children who are allergic to milk can help them overcome their allergies, according to the findings of a small study at Johns Hopkins Children's Center and Duke University.

The findings were presented Feb. 28 at the annual meeting of the American Academy of Allergy, Asthma & Immunology .

The approach, known as SLIT (sublingual immune therapy), involves giving children small but increasingly higher doses of the food they are allergic to until their immune systems "learn" to tolerate the food without triggering an allergic reaction or triggering only mild symptoms. Previous research from Hopkins Children's showed that a similar approach known as oral immunotherapy can successfully treat children with milk allergies. Unlike SLIT, oral immunotherapy involves consuming milk protein rather than merely placing it under the tongue.

The current study suggests that both approaches could be effective in treating milk allergies in most patients, authors say, but that oral immunotherapy appears to be slightly more effective than SLIT. The investigators caution that the results are preliminary and that the two approaches must be compared in larger groups before their equal efficacy can be confirmed.

While both approaches work by exposing the patient to progressively higher doses of the allergenic food, SLIT is done with lower doses -- and therefore with lower risk for a severe allergic reaction. Researchers caution that both therapies can lead to violent allergic reactions in some patients, and should be always done under a doctor's supervision.

"We are very excited to see that both approaches can achieve significant improvement in children with milk allergies, but we continue to see slightly better tolerance in children on oral immunotherapy," says lead investigator Robert Wood, M.D., director of Allergy & Immunology at Hopkins Children's. "Nonetheless, SLIT emerges as a new, if slightly less powerful, weapon in our arsenal."

In the study, all 30 children ages 6 to 17 were treated with milk drops under the tongue (SLIT) for several weeks until they built up their tolerance. Once minimum tolerance was achieved, the children were divided into two groups. Ten children continued their SLIT treatment while the other 20 consumed milk powder by mouth (OIT). After three months of treatment with increasingly higher doses of milk protein, all children underwent a food challenge, which involved drinking milk under a doctor's supervision.

All children in the "by mouth" group were able to drink on average seven times more milk without an allergic reaction or with mild symptoms compared to their baseline milk challenge before the treatment. Nine of the 10 children treated with milk drops under the tongue, were able to do so.

Children in both groups experienced allergic symptoms equally often during the treatment. In the "under the tongue" group, 33 percent of the 3,619 doses of milk administered caused symptoms, compared to 35 percent of the 3,773 doses in the "by mouth" group. Most symptoms were mild, with the most common ones being mouth and throat itching and irritation. Abdominal and respiratory symptoms occurred very infrequently, the researchers report.