Dr. Roy

Allergen Desensitization > Sublingual Immunotherapy

Treatment for Allergic Rhinitis and Allergic Asthma – Nothing to Sneeze or Wheeze About

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 long-term treatment alternative.

Allergy shots involve frequent injections of increasing amounts of allergen extract. They can be effective at controlling symptoms of allergic rhinitis and allergic asthma, but the injection schedule can be difficult to maintain, local reactions to the injections are common, and severe allergic reactions and even deaths have been rarely reported.

Another form immunotherapy is currently being practiced all over the world is Sublingual Immunotherapy (SLIT) which involves a dosing schedule of increasing amounts of allergen, much like the shots. However, rather than shots, the allergens are administered in a liquid (drops) or tablet form under the tongue. SLIT is currently being used in Europe and some countries in South America. Based on reviews of research projects done both in the US and overseas, SLIT is a safe and effective treatment for allergic rhinitis and allergic asthma.

SLIT appears to have a favorable safety profile. In one review of the literature, the authors estimated that in approximately 1.2 million doses administered to 4400 patients, there were no serious, “life-threatening reactions”. There are reports of anaphylaxis with SLIT, but the incidence is very rare. The primary symptoms reported by subjects receiving SLIT included mild “local” itching/burning of the mouth or lips, increase in rhinitis symptoms, gastrointestinal symptoms, and rarely, an increase in asthma symptoms. The reactions reported by subjects receiving SLIT were only significant enough to make the subject stop taking SLIT in less than 5% of the cases. SLIT has been studied in children as young as a year old. The primary symptoms reported by parents were oral itching, itchy skin, abdominal pain, and nausea and vomiting

The effectiveness of SLIT has been studied in both adults and children. Some studies report that SLIT takes at least 2 years of treatment before subjects see improvement in symptoms. Other studies show improvement within a single year of therapy. One large review of over 100 SLIT research studies demonstrated that about 1/3 of studies showed significant improvement in symptoms while 1/3 showed no significant improvement. The variation in  effectiveness had been attributed to the differences in the dose of allergen used for the various studies. In general, the higher doses of allergen appeared to have the largest impact
on symptom improvement. SLIT has become a very useful treatment of allergic diseases.

How does the process work?

The first step is to confirm a patient’s allergies through allergy testing. Then, a custom-mixedvial of drops is prepared for the patient. The patient takes drops under the tongue daily. During the first four months, called the escalation phase, the dosage is gradually increased.After that, in the maintenance phase, the patient takes the same dose of drops each day.

Is sublingual immunotherapy safe?

It is very safe, for both adults and children. Patients take the drops in the convenience of their own homes instead of going to a doctor’s office every week for shots. The World Health Organization (WHO) has endorsed sublingual immunotherapy (SLIT) as a viable alternative to injection immunotherapy (SCIT).

How long must I continue the treatment?

We recommend that patients keep using the drops for three to five years so that the body will build up a lasting immunity


Passalacqua G et al: 30 Years of Sublingual Immunotherapy. Allergy. 2020;75:1107–1120.

Cox L, Sublingual immunotherapy and allergic rhinitis. Curr Allergy Asthma Rep. 2008

Cox L. Sublingual immunotherapy in pediatric allergic rhinitis and asthma: efficacy, safety and practical considerations. Curr Allergy Asthma Rep 2007 Nov;7(6):410-20.

Cox LS, Linnemann DL, Nolte H, Weldon D, Finegold I, Nelson HS. Sublingual immunotherapy: A comprehensive review. J Allergy Clin Immunol 2006. May;117(5):1021-1035.

Passalacqua G, Durham SR in cooperation with the Global Allergy and Asthma European Network. Allergic Rhinitis and its Impact on Asthma update: Allergen Immunotherapy. J Allergy Clin Immunol 2007 April;119(4):881-891.

Smith, H, White P, Annila I, Poole J, Andre C, Frew A. Randomized controlled trail of highdose sublingual immunotherapy to treat seasonal allergic rhinitis. J Allergy Clin Immunol 2004. 114(4);831-837.

Wilson DR, Lima MT, Durham SR. Sublingual immunotherapy for allergic rhinitis: systematic review and met-analysis*. Allergy 2005;60:4-12.

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