SLIT Treatment (Allergy Tablets) for Allergic Rhinitis Nothing to Sneeze About
This article has been reviewed by Thanai Pongdee, MD, FAAAAI
Allergic rhinitis, sometimes referred to as hay fever, is an inflammatory disease that causes sneezing, itchy/watery eyes, itchy/runny nose and congestion. For millions of sufferers, antihistamines and nasal corticosteroid medications provide temporary relief of symptoms. For others, allergy shots (subcutaneous immunotherapy or SCIT) are a treatment option that can provide long-term relief.
Allergy shot treatment involves two phases. The first phase involves frequent injections of increasing amounts of allergen extract. This is followed by a maintenance phase, during which the injections are given about once a month. Although allergy shots can be very effective at controlling symptoms of allergic rhinitis, the schedule can be difficult to maintain. Local reactions, for example swelling and itchiness at the injection site, are also common allergy shot side effects. In addition, severe allergic reactions can occur but are relatively uncommon and even deaths have been reported.
Another form of allergy immunotherapy was recently approved in the United States called sublingual immunotherapy (SLIT) allergy tablets. Rather than shots, allergy tablets involve administering the allergens in a liquid or tablet form under the tongue generally on a daily basis.
What Are the Treatments the FDA Approved?
The U.S. Food and Drug Administration (FDA) recently approved three allergy tablets products. Two are directed at different kinds of grass pollen and one is for short ragweed. The two grass pollen allergy tablets are Oralair® (Stallergenes), which has five kinds of northern grass pollen, and Grastek® (Merck), which has timothy grass pollen. The short ragweed allergy tablet is called Ragwitek® (Merck).
These three allergy tablets provide an additional option for the treatment of allergic rhinitis/rhinoconjunctivitis triggered by ragweed or timothy/northern grasses.
SLIT (allergy tablets) is similar to SCIT in terms of the effectiveness of controlling allergy symptoms, and both have been shown to provide long term improvement even after the treatment has ended. However, the treatment is only effective for the allergen contained in SCIT or allergy tablets. If someone is allergic to ragweed and trees, the ragweed tablets/shots would only help control ragweed symptoms during ragweed season.
Allergy tablets have a more favorable safety profile than SCIT, which is why it does not need to be given in a medical setting after the first dose. However, the FDA-approved product information of the three SLIT tablets includes a warning about the possibility of severe allergic reactions from SLIT and a recommendation that an epinephrine autoinjector be prescribed to patients receiving allergy tablets in the event a severe allergic reaction should occur.
The primary side effects of allergy tablets are local reactions such has itching or burning of the mouth or lips and less commonly, gastrointestinal symptoms. These reactions usually stop after a few days or a week.
SLIT Liquid Drops
There are currently no FDA-approved SLIT liquid (drops) formulations. The effectiveness of SLIT with U.S. allergen extract drops is still under investigation and the effectiveness of mixtures of allergens is not known. There is a wide range of effective and ineffective doses of SLIT liquid formulations across the published literature and expert opinion has been that each formulation needs to prove its safe and effective dosing regimen.
Another important question is optimal starting time and schedule, i.e. is it best to start some time before the season (e.g., 2 or 4 months) or can it be started just as the season begins? Does it have to be administered all year-long or can it just be given before and during the season? The allergy tablets dosing regimen will clearly impact treatment costs, which will greater than SCIT due to higher extract costs associated with daily dosing.
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