The American Academy of Allergy, Asthma & Immunology and the European Academy of Allergy and Clinical Immunology have collaborated to produce a comprehensive review of allergy immunotherapy. The report focuses on the current state of both subcutaneous (allergy shots) and sublingual (allergy drops or tablets) immunotherapy.
The report, which was officially endorsed by both academies and written by a panel of experts selected by each, includes a thorough review of where immunotherapy stands as a treatment, how it can be improved, and what its future holds.
The authors note that both drops and shots have been shown to be effective for environmental allergies such as allergic asthma, rhinitis and atopic dermatitis (eczema). Only injections have been effectively used for insect venom allergy. Studies in the past had looked at using shots for peanut allergy, but anaphylactic reactions occurred and the experiments were abandoned.
More recently, clinical trials have been conducted analyzing the potential for sublingual therapy for food allergies, with promising results. More research is needed, however, before this becomes a viable treatment for food allergy.
The consensus report compares the two types of immunotherapy examining side effects, dosing and how effective they are. For subcutaneous therapy for environmental allergies, side effects were found to range from local and mild to systemic. Systemic reactions can include anaphylaxis, although this is fortunately uncommon. (In an AAAAI/EAACI survey, 0.1 percent of injections led to systemic reactions between 2007 and 2009.)
This potential for a severe reaction is the reason behind guidelines that recommend any patient receiving allergy shots remain under supervision in the doctor’s office for 30 minutes after the treatment.
By comparison, the sublingual immunotherapy side effects were generally mild. The most common side effects were local reactions, including itching and minor swelling. These side effects usually only occurred near the beginning of the treatment, and tended to resolve on their own as treatment continued.
No systemic reactions have been reported with this form of immunotherapy. An advantage with the oral drops or tablets is that once proper dosing is established, the treatment can be taken at home without the need for monitoring in the allergist’s office.
In terms of effectiveness, the authors note that after several years of treatment, both forms of immunotherapy result in the individual being desensitized to environmental allergens for seven to 12 years.
The report also finds that both therapies appear to reduce the chance of rhinitis developing into allergic asthma, or of new allergies developing in people who are sensitive to just one allergen.
The authors raise some issues that still require attention. One of the biggest is that researchers still don’t know why both types of immunotherapy are highly effective for some patients, yet have little or no beneficial effect for others.
The report also finds that patients commonly don’t adhere to immunotherapy regimens, likely because of the long duration of the treatment and the number of shots or tablets required.
The authors conclude that, despite its effectiveness, immunotherapy “remains a niche treatment secondary to symptomatic drugs because of its cost, long duration of treatment, and concerns regarding safety and effectiveness.” They see the need for standardized approaches and regulation, and further research to predict patient responses to move immunotherapy successfully forward.