Sublinguinal immunotherapy (SLIT) involves putting small, and then gradually increasing amounts of allergen extracts under the tongue in order to desensitize the patient to the allergen. The process is colloquially referred to as "taking allergy drops," and is an alternative treatment to allergy shots. Sublinguinal immunotherapy, while widely used in Europe, is not yet FDA approved in the United States. While positive results may occur fairly rapidly, a full course of treatment is usually considered to take about 5 years.
Sublinguinal immunotherapy is usually administered daily, or multiple times per week, for a period of years, and is normally self-administered, except by children. Studies are presently underway to determine appropriate dosages of sublinguinal allergens and whether it is more helpful to administer such dosages before or during seasons during which the patient is most symptomatic.
Candidates for Sublinguinal Immunotherapy
Sublinguinal immunotherapy can be used to treat many different types of allergies, including those to dust, ragweed, pollen, pet dander and mold. It can also be used to treat food allergies. Candidates for this treatment are usually patients who suffer from allergic rhinitis, allergic conjunctivitis, or allergic asthma. Patients of all ages have been shown to tolerate the treatment well and to benefit from it. As with allergy shots, pregnant patients may continue sublinguinal immunotherapy during pregnancy, but it is not deemed advisable for patients to begin the therapy while pregnant. Because asthma symptoms sometimes worsen with sublinguinal immunotherapy, patients who are severely asthmatic must be monitored closely.
Most of the research on sublinguinal immunotherapy has focused on patients with a single allergy, such as to grass or dust mites. It is possible that patients with multiple allergies may be more difficult to treat with sublinguinal immunotherapy because of the number of allergen extracts necessary for administration.
Benefits of Sublinguinal Immunotherapy
There are many benefits to treatment with allergy drops as opposed to other methods of allergy control, such as allergy shots. These advantages include:
- Reduced number of doctor visits
- Convenience of home treatment
- Portability of treatment
- Ability to treat a broad spectrum of allergic conditions
- Reduced need for antihistamines or other medications
- Extremely rare serious reactions
- Fewer mild to moderate reactions than in patients taking allergy shots
While studies of sublinguinal immunotherapy show promise, so far results have been inconsistent; as many as one-third of research studies have not substantiated any benefit to sublinguinal immunotherapy beyond that of placebo treatment. Nonetheless, many allergy sufferers have been demonstably helped by sublinguinal immunotherapy treatments.
Risks of Sublinguinal Immunotherapy
Research data covering the past 10 years, indicates that out of 100 million cases of sublinguinal immunotherapy, there has been only one recorded anaphylactic reaction and there have been no fatalities. Mild side effects, such as an itchy mouth, have been documented in many patients, and moderate side effects have been recorded in some patients, during at least some dosage administration. Moderate reactions include:
- Irritation of the mouth, lip, and tongue
- Itching, swelling and redness of the eyes
- Nausea, vomiting, abdominal cramping, diarrhea
- Sneezing, nasal itching, congestion
- Asthma symptoms
- Urticaria (hives)
- Angioedema (swelling)
In spite of the occasional occurrence of these complications, sublinguinal immunotherapy is considered safe home treatment, as long as patients are monitored closely by medical personnel.
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