Specific Immunotherapy (SIT) refers to a treatment for respiratory allergic diseases which can improve allergy symptoms, reduce the need for medications to treat the symptoms, and it also has long-term effects in preventing the development of asthma and new allergies.1 SIT primarily utilizes Subcutaneous Immunotherapy (SCIT) and/or Sublingual Immunotherapy (SLIT) to act on immunological mechanisms which alter the allergic immune response.

An allergic response occurs when some children or adults are exposed to environmental botanicals (ragweed, hay, pollen, etc.), animal fur or dander, or insects (dust mites) or their venom (wasp/bee stings). The allergic immune response is due to a subset of T-helper blood cells or lymphocytes (Th2), and characterised by production of cytokines like IL-4, and IL-5 (certain types of cell proteins). The immunological changes which follow Specific Immunotherapy lead to potential curative effects for the patient.

Immunotherapy also suppresses the allergic response through increased production of IgG4 antibodies, the primary antibody of blood and intercellular fluids. Specifically, IgG4 can influence the allergic response in many ways assisting in the transition from a Th2 (allergic) to a Th1 (non-allergic) response profile. SIT can be considered as one of the first-line therapeutic treatments for allergic rhinitis, but is also very useful as a secondary preventative treatment for respiratory allergic diseases.


The outcome of immunotherapy is commonly an early reduction in clinical symptoms during treatment, and its long-term effects even after discontinuation of SIT is the potential prevention of asthma and new allergies. The efficacy of SIT is a function of the duration of immunotherapy, whereby the positive immunological changes leading to long-term benefits may occur the longer one is receiving therapy. Only SIT has been documented as the therapy with long-term, preventative potential. Symptomatic treatment and avoidance measures do not have this same benefit.


Sublingual Immunotherapy (SLIT) is an alternative way to treat allergies without injections and is well-suited to the needle phobic, children, travelers and the elderly. An allergist gives a patient very small doses of an allergen sublingually to boost tolerance to the substance and reduce symptoms.

Currently, the only forms of SLIT approved by the US FDA are tablets for ragweed and grass pollen. The safety and efficacy of sublingual allergy liquid solutions are still being established by the FDA, and they are only used off-label in the United States. In Canada, off-label SLIT is commonly used in naturopathic medical practice and this form of therapy is being quickly accepted by traditional allopathic medical doctors.


A doctor must first use allergy testing to confirm the patient’s sensitivities. Once this is determined, an allergen extract is prepared as a tablet or in liquid form according to the doctor’s prescription. The patient is directed to keep it under the tongue for one to two minutes and then swallow the extract. The process is repeated from three days a week to as often as daily with recommendations that therapy is continued for three to five years to develop a lasting immunity.


Most clinical trials and surveys published over the past 20 years show that SLIT is relatively safe and effective for the treatment of rhinitis and asthma caused by allergies to dust mites, grass, ragweed, cat dander, and tree pollens. Evidence is emerging that SLIT may be effective for treating the red, itchy eyes caused by pollen during hay fever season. 3-7 In addition, it might prove an effective therapy for children with mild atopic dermatitis (eczema) and is currently being studied for its potential in treating food allergies. Currently, the best option for people with food allergies is to strictly avoid that food.

Side effects that may appear in both children and adults are usually local and mild, most often occur early in treatment, and include itching in the mouth or stomach problems. These can usually be managed by dose adjustments. Very rarely, severe allergic reactions (anaphylaxis) have been reported using SLIT. Therefore this treatment is best prescribed by a medical practitioner experienced in the field of allergy.


For the most part, SLIT risks relate to the nature of the treatment: it is administered at home and without direct medical supervision. Patients should therefore receive clear guidance from their doctor on managing adverse reactions and treatment interruptions and should know when to consult the prescribing doctor. Learn more about this form of allergen therapy by contacting our office.


Children and adults can both receive SLIT. If you are an older adult and considering SLIT but have medical conditions such as severe asthma, high blood pressure or other serious illnesses, please discuss the therapy with your allergist or physician first.

Regardless of your health condition, you and your allergist or physician should discuss Sublingual Immunotherapy, including:

  • The type of symptoms you are having, the severity and whether they are seasonal or year-round
  • Whether medications and/or environmental controls are helping your allergy symptoms
  • Any concerns about long-term medication use
  • The commitment to treatment (sublingual treatment requires a daily dose)
  • The cost involved and individual insurance coverage

SLIT is not used to treat food allergies but there is research underway to evaluate this form of treatment.


Sublingual Immunotherapy works very much like a vaccine. You receive gradually increasing amounts of allergens, leading the body to develop immunity or improved tolerance to the allergens.

Sublingual Immunotherapy occurs in two phases:

  • Build-up Phase. This involves receiving increasing amounts of the allergens once a day for a short time ranging from a few days to a few weeks.
  • Maintenance Phase. This begins when the effective maintenance dose has been reached, based on your allergen sensitivity and response to the Build-up Phase. During the Maintenance Phase, the strength of the allergens is higher and at an optimal concentration and effectiveness.

You may notice a decrease in symptoms during the Build-up Phase, but it may take as long as 3 months on the maintenance dose to notice more improvement. The recommended duration of maintenance treatment is generally three to five years. The reason for this is because it has been shown that the improvement from Sublingual Immunotherapy will persist even when they are stopped after that duration, and can even prevent the development of new allergies and the onset of asthma.


The efficacy of SLIT appears to be related to the length of the treatment program as well as the dose of the allergen. Some people experience lasting relief from allergy symptoms, while others may relapse after discontinuing allergy shots too soon. If you have not seen improvement after 1-2 years of maintenance therapy, your physician will work with you to discuss other treatment options.

A failed response to SLIT may be due to many factors:

  • Inadequate dose of allergen in the allergy vaccine
  • Missing allergens not identified during the allergy evaluation
  • Allergens may have changed since the previous allergy evaluation
  • High levels of allergen in the environment
  • Significant exposure to non-allergic triggers, such as tobacco smoke
  • Not taking the treatment as prescribed on a regular basis


The most common reaction is itching in the mouth. This may happen immediately or several hours after the treatment and may last up to 24 hours. In some cases especially in the Build-up Phase, symptoms may include increased allergy reactions such as sneezing or nasal congestion. These local reactions at injection sites and transient increases in symptoms during the Build-up Phase are not considered serious.
Serious reactions to SLIT are extremely rare. When they do occur, they require immediate medical attention. Symptoms of an anaphylactic reaction can include swelling in the throat, wheezing or tightness in the chest, nausea and dizziness. Most serious reactions develop within 30 minutes of the allergy treatment. For some high risk patients such as those with a history of severe asthma, or previous severe non-anaphylactic reactions to immunotherapy, it may be necessary to have an Epipen® at home.


SLIT should be postponed if you are sick especially if you have a fever or if you are having severe, uncontrolled problems with asthma. If you have missed doses, the dosage and strength may need to change depending on how long you have missed. Please discuss precautions with your doctor if anything like this happens or if you have other questions.


  • If you have severe, uncontrolled asthma
  • If you have chronic intestinal conditions such as Eosinophilic Esophagitis
  • If you are taking blood pressure medications called Beta Blockers (please consult with your doctor)
  • If you have any severe medical condition that puts you at risk towards an unstable situation (for example cardiac conditions)
  • If you have had previous severe anaphylactic reactions to immunotherapy

SLIT may be continued if you get pregnant, but should not be started during pregnancy.


  1. Des Roches A, et al. Immunotherapy with a standardized Dermatophagoides pteronyssinus extract: specific immunotherapy prevents the onset of new sensitizations in children. J Allergy Clin Immunol. 1997 April;99(4):450-453.
  2. Jacobsen et al.: Allergen-specific immunotherapy provides immediate, long-term and preventive clinical effects in children and adults: the effects of immunotherapy can be categorised by level of benefit -the centenary of allergen specific subcutaneous immunotherapy. Clinical and Translational Allergy 2012 2:8.
  3. Sublingual immunotherapy: World Allergy Organization position paper 2013 update. World Allergy Organization Journal 2014, 7:6
  4. Allergen Immunotherapy: A practice parameter third update Task Force Report. Linda Cox MD, Richard Lockey MD, JACI 2010
  5. Specific Allergy Immunotherapy for Allergic Rhinitis: Subcutaneous and Sublingual. Linda Cox MD, Dana Wallace MD, Immunol Allergy Clin N Am 31 (2011) 561-599
  6. Update on allergy immunotherapy: American Academy of Allergy, Asthma & Immunology/European Academy of Allergy and Clinical Immunology/PRACTALL consensus report. A. Wesley Burks, MD et al. JACI May 2013 Vol 131, Issue 5, 1288-1296
  7. Randomized, double-blind, placebo-controlled trial of standardized ragweed sublingual-liquid immunotherapy for allergic rhinoconjunctivitis. Peter Creticos, MD et al. JACI 2014;133:751-8

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