Sublingual immunotherapy is the practice of administering allergen extract droplets under the tongue. (Credit: Getty Images)

What if all it took to get rid of seasonal allergies was holding a few drops of liquid under your tongue for a few seconds a day?

In Europe, sublingual immunotherapy, the practice of gradually desensitizing the immune system to allergens by administering allergen extract droplets under the tongue, has been common practice for treating allergies and certain asthmas for decades. But in the United States, the therapy is not yet approved by the Food and Drug Administration.

"We're just behind the times," said Dr. Sandra Lin, an allergist at Johns Hopkins University School of Medicine who conducted a review of 63 studies on the therapy and published her findings in the Journal of the American Medical Association, or JAMA, today.

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Lin said she wasn't surprised to learn that the studies concluded sublingual immunotherapy worked. Allergists in the United States, including Lin, have used the extracts off-label for years. They are FDA-approved to be injected into the fatty tissue, but can be much more easily administered by just placing droplets under the tongue.

"It modifies the immune system so it's more tolerant to what you're allergic to," Lin said, adding that the under-the-tongue therapy can be done at home, unlike injections which should be done in a doctor's office. "It's all about convenience and accessibility because being able to dose at home opens it up to a huge number of people, particularly children."

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She said she published the review of 63 studies in JAMA to gain raise awareness about it as an effective therapy. Although allergists are free to use it off-label, she said FDA-approval would be ideal toward determining the best dosage and concentration of the liquid allergen extract.