Sublingual Immunotherapy (SLIT)
Immunotherapy is a medical therapy which treats the cause of allergies by giving a patient small doses of what he or she is allergic to, which decreases sensitivity to the allergen and reduces allergic symptoms. Unlike injection immunotherapy, in which the allergic substance is administered as shots into the upper arm, sublingual immunotherapy (SLIT) is given by dropping the substance under the tongue. The goal of treatment is to cure patients of their immune system’s over-reactivity to allergens. This could be sensitivities to pollen, pet dander, dust mites, foods, etc., with reactions typically occurring in the sinuses, lungs, skin and/or gastrointestinal tract.
While both types of immunotherapy can by effective, SLIT has some distinct advantages over allergy injection therapy. Because SLIT is less likely to cause adverse reactions, it can be self-administered at home, so there is no need for weekly medical appointments. People who travel frequently may find SLIT more convenient, since they will not have to find a new doctor’s office when they are out-of-town. Allergy drops provide the same end result as allergy shots, but without the pain, making it a good option for people who have a fear of syringes. SLIT can be given to highly allergic infants and young children who are not old enough for allergy injections.
The American Academy of Otolaryngic Allergy endorses SLIT, and it’s used as the “gold standard” of care in many parts of Europe. However, the U.S. Food and Drug Administration classifies it as an “off label” therapy. For this reason, many insurance companies do not cover it and patients typically pay for SLIT as an out-of-pocket expense. Injection therapy, on the other hand, is typically covered by insurance. However, the allergy drops may still be a better option financially when you consider the cost of travel to the office for traditional allergy shots and the “cost” of time spent in the office for observation afterwards.
How does SLIT work?
The first step in the sublingual immunotherapy treatment process is undergo allergy testing to find out what allergen triggers your symptoms. Once this has been determined, an extract of the substance will be prepared in drop form, which you will take once a day. Each time, you will need to hold the dropper up to your mouth and then squeeze it so the drops “land” under your tongue. The liquid is held under the tongue for approximately one minute before being swallowed or spit out.
With repeated exposure to the allergen, your body will begin to form IgG antibodies, which “block” that specific allergen and prevent an allergic reaction. These are antibodies that people without allergies have a healthy supply of. But people with allergies lack IgG antibodies. Instead, they may have an overabundance of IgE antibodies, which sit on the surface of mast cells (defensive white blood cells). When allergens enter the body, the IgE antibodies attack them, which releases the histamines that are inside the mast cells. Histamine is the substance the produces the allergic symptoms like sneezing, rashes, itching, hives, mucus production, etc. After you’ve undergone SLIT, if you are exposed to an offending allergen, it will be blocked by IgG antibodies before it can react with IgE antibodies. This means no allergy symptoms are triggered.
At first, you’ll receive just a very small dosage of the offending allergen. Gradually, the amount will be increased over time as your immune system adjusts to the allergen and becomes less sensitive, leading to a reduction in the severity of your symptoms. Most patients report some improvement after just a few months of treatment.
How long is the treatment period?
SLIT in not an overnight fix. Rather, it takes time to build up enough blocking antibodies and modify the immune system to achieve long-term relief from symptoms. The duration of therapy varies from person to person, with some individuals needing to use the drops longer than others. In general, we recommend patients continue with the therapy for 3 to 5 years so that the body will be able to develop a lasting immunity to the allergen. While this may seem like a long time, the payoff is usually well worth it for people with severe allergies, as symptoms will be dramatically reduced, or in many cases, disappear completely.
Will other allergy medications need to be taken while on SLIT?
The majority of patients will continue to need allergy medications as they start SLIT. In the beginning of treatment, there’s often a “scissor effect” where IgE levels temporarily increase before beginning to decline and before blocking IgG antibodies begin to build up. As symptoms start diminishing, most patients will be able to “cut down” on their allergy medications. While on SLIT, you will continue to have follow-up appointments with your doctor every 3 to 6 months to review your progress and make any adjustments on medications. While the goal of SLIT is to completely eliminate allergic symptoms and the need for medications, for some patients this is not possible. But even in these cases, there is usually enough improvement in symptoms to warrant a reduction in the strength or frequency of medications.
Is SLIT safe?
SLIT has been demonstrated to be very safe for both adults and children. To date, there has never been a reported case of anaphylaxis or death with SLIT, and serious reactions are extremely rare. Mild side effects, such as an itchy mouth, occur in many people initially and then tend to resolve over time. Moderate side effects have been documented in some cases, including irritation of the lip, mouth or tongue; gastrointestinal upset (nausea, vomiting, diarrhea and abdominal cramping); nasal congestion, itching and sneezing; red, itchy or swollen eyes; asthma symptoms; and hives, rashes or itchy skin.
While the risk of a life threatening reaction with SLIT is exceedingly low, patients on treatment should carry an Epi-Pen at all times. Prior to beginning SLIT, patients are instructed in the use of their Epi-Pen with a trainer device in our office. In the event that you develop a reaction, you would use your Epi-Pen and call 911 for transport to your closest emergency hospital for further evaluation and treatment.
Schedule an appointment to find out if sublingual immunotherapy is right for you!
Like all medical therapies, sublingual immunotherapy is not suitable for every patient. There is evidence that allergy drops work very well for patients with one type of allergy (such as a grass or dust mite allergy), but allergy injections work better for patients with multiple environmental allergies (to molds, pollens, pet dander, etc.), given the large volume of different allergen extracts that would need to be taken.
To find out if you are a candidate for SLIT, please call our office at 404-257-1589 to schedule a consultation with one of our allergy specialists. Whether you choose to manage your allergies with SLIT, traditional allergy shots or other allergy medications, we will work with you to develop a treatment regimen that is right for you.