She said the results from European trials cannot be simply translated to the United States because of differences in the potency of the allergen extracts used.
"We need studies to see what are the most effective doses for U.S. patients," Lin said.
The idea of taking pills instead of getting shots definitely appeals to patients, said Dr. Harold Nelson, an allergy specialist at National Jewish Health in Denver, who wrote an editorial published with the study.
But his advice to U.S. patients was to wait for products to be approved by the FDA.
Even if your doctor offers under-the-tongue immunotherapy, "there's no guarantee" it would be the same as the products studied in clinical trials, Nelson said. He noted that U.S. doctors commonly give a patient a mix of different allergen extracts, because that's how it is done with allergy shots.
But the under-the-tongue products used in clinical trials have contained only a single allergen extract, Nelson said.
Like allergy shots, immunotherapy pills and drops take time to work. They need to be taken daily, for a few years. And they're not cheap, Nelson pointed out. They can cost $2 or more a day, and insurance companies may not cover it.
As far as safety, Lin said the trials her team reviewed found no serious allergic reactions to the immunotherapy. Most often, patients had "local" reactions, such as throat irritation and swelling or itching in the mouth.
"But we didn't do an exhaustive safety review," Lin stressed. It's possible that in the real world, some patients have had more serious reactions.
Another big question is whether under-the-tongue immunotherapy is as effective as traditional allergy shots, Nelson said. "It's not clear how they compare head-to-head," he said.
On the other hand, Lin said many more U.S. patients will try immunotherapy if under-the-tongue options are approved. That's especially true of kids. "Who's going to be the least likely
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