Oral tablets for grass pollen allergies, which are available in Europe and the U.S., offer only a small benefit for people with seasonal allergies, and more than half will have side effects from the medication, according to a new review of existing research.
“The reported benefit is very small on average,” said lead author Dr. Danilo Di Bona of the Azienda Ospedaliera Universitaria Policlinico di Palermo in Italy. “This means that some patients will respond, but the majority will not, and it is not possible to predict who will respond to the treatment.”
An injectable version of the same therapy, which is also available, is preferable, since more patients will respond to it, he said.
The researchers considered 13 randomized controlled trials comparing under-the-tongue “meltaway” immunotherapy tablets with placebo pills, and measuring changes in reported allergy symptoms and the use of other allergy medications. In total, the trials included more than 4,000 patients with seasonal allergies.
All of the studies found some symptom alleviation with the immunotherapy tablets, but six of the 13 did not demonstrate more improvement than was seen in the placebo group.
In seven studies, the group taking the immunotherapy tablets decreased their use of other medications like antihistamines and corticosteroids, but not in the others.
About 60 percent of people taking the immunotherapy tablets suffered a side effect due to the medication, usually a moderate one like mouth itching or burning and gastrointestinal tract symptoms, compared to 21 percent of those in the placebo group, as reported in JAMA Internal Medicine.
Of the 4,659 people included in the trials, seven people – all in the immunotherapy group – reported a serious allergic side effect requiring epinephrine, a rescue treatment for potentially life-threatening allergic reaction.
The benefit of the tablets originally reported from these randomized controlled trials was overestimated, Di Bona said.
“With the metric we used, that is the one suggested by the World Allergy Organization, the real difference between (under-the-tongue tablets) and placebo was correctly estimated, and the benefit was comparable to placebo,” and below the 15 percent difference required by the U.S. Food and Drug Administration (FDA), Di Bona told Reuters Health by email.
Last year, the FDA approved two types of immunotherapy tablets for pollen allergies, including Merck’s product, Grastek and Oralair from French manufacturer Stallergenes S.A.
Under-the-tongue Grastek tablets can be prescribed to anyone age five to 65 who has grass pollen allergies and suffers from sneezing, runny nose and itchy or watery eyes. As directed, it can be taken daily for 12 weeks before springtime, the grass pollen season, and throughout the season.
In an editor’s note accompanying the new study, Dr. Patrick G. O’Malley of the Uniformed Services University in Bethesda, Maryland, called the immunotherapy’s benefit an “unimpressive small effect.”
Doctors should be aware of these data, in addition to the cost of these medications, which is approximately $90 for a three-month supply, plus the requirement to co-prescribe an epinephrine autoinjector, writes O’Malley, who was not involved in the study.
“Sublingual immunotherapy may seem more convenient than nasal corticosteroids or subcutaneous immunotherapy and therefore tempting to prescribe, but the evidence shows minimal benefit and moderate adverse effects for patients with seasonal grass pollen allergies,” he writes.
Untreated or inadequately treated seasonal allergies can cause sleep and mood disorders and impair school or work performance, Di Bona said. About 20 percent of Americans suffer from these allergies, largely due to grass pollen, he said.
Other available treatments, like antihistamines and nasal or oral corticosteroids, are effective in controlling most symptoms, Di Bona said.
Immunotherapy tablets, though their mechanism is poorly understood, modify the immune system to induce a kind of tolerance for the allergen, he said.
“The treatment would be worth the expense if the response rate was higher,” he said.