Background

Allergen immunotherapy is used in patients who suffer from severe allergies or who experience allergy symptoms more than three months in a year. Allergen immunotherapy involves administering injections of a diluted allergen in two phrases termed the build-up phase and the maintenance phase.

According to the American Academy of Allergy Asthma & Immunology, immunotherapy is only recommended for patients who have allergic asthma, allergic rhinitis, conjunctivitis, and stinging insect allergies. Immunotherapy is not recommended for food allergies.

In addition to traditional allergy shots, there are several other immunotherapy techniques. One technique is rush immunotherapy, which involves a more rapid build-up phase. The other two are oral and intranasal immunotherapies which are similar to traditional immunotherapy except that the diluted allergen is administered orally or intranasally.

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Safety Safety definitions

Children: Sublingual and subcutaneous allergen immunotherapy is approved by the FDA for use in children 5 years and older.

Pregnancy: There is insufficient reliable evidence about the safety of allergen immunotherapy in pregnancy; avoid use or use with caution.

Lactation: There is insufficient reliable evidence about the safety of allergen immunotherapy in lactation; use with caution.

Effectiveness Effectiveness definitions

INSUFFICIENT RELIABLE EVIDENCE TO RATE

Allergic rhinitis (hayfever). Clinical research shows that administrating intranasal immunotherapy of birch tree, grass, and dust mite allergen extracts may reduce nasal congestion and sneezing in people with allergic rhinitis.

More evidence is needed to rate allergen immunotherapy for this use.

Natural Medicines rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

Dosing & administration

Adverse effects

General: The most common adverse effects of allergen immunotherapy are allergic reactions. Allergic reactions may be local, which include redness and swelling at the injection site. Less common allergic reactions are systemic and may include worsened nasal congestion, hives, or sneezing. Additionally, there have been rare reports of anaphylaxis. Rush immunotherapy involves a greater risk of allergic reactions compared to the other immunotherapies.

Interactions with pharmaceuticals

None known.

Interactions with herbs & supplements

None known.

Interactions with foods

None known.

Interactions with lab tests

Interactions with diseases

ASTHMA: Patients with non-allergic asthma may be at a higher risk for severe adverse reactions to allergen immunotherapy; use with caution or avoid use.

Mechanism of action

Allergen immunotherapy works like a vaccine. Rather than treating the symptoms of allergies, allergen immunotherapy works through the immune system, which is responsible for an allergic reaction. An allergic reaction occurs when the body is exposed to an antigen (foreign substance like pollen, dust mites, mold and pet dander). The white blood cells produce an antibody (immunoglobulin E) to the antigen. This process is called sensitization, after which the immune system is able to respond more quickly and strongly to the antigen.

Once the body is sensitized, the immune cells will release chemical mediators like histamine when the antigen enters the body. These mediators cause inflammation, as well as allergy symptoms, such as sneezing, runny nose, watery eyes and hives.

Allergy shots theoretically desensitize the patient's immune system so it will not react and develop tolerance to the antigen. As a result, allergy symptoms are decreased when the patient is exposed to the particular allergen again.