Allergen immunotherapy for allergic rhinitis

Allergen immunotherapy can be very effective in the management of allergic rhinitis; it is the only treatment that alters the course of the condition. Its use is largely limited to patients with moderate to severe symptoms that are incompletely or poorly controlled with drug treatment and allergen avoidance.

Specific allergen sensitivities must be identified by in vivo skin testing or in vitro serum testing. These tests are usually carried out and interpreted by a clinician with expertise in allergy. Allergen immunotherapy is more successful for patients who have a single sensitivity, but patients with multiple sensitivities can still achieve good results.

The treatment course of subcutaneous or sublingual immunotherapy is around 3 years. Both sublingual and subcutaneous immunotherapy are effective for patients with allergic rhinitis who are sensitised to grass pollen or dust mites; subcutaneous immunotherapy is also available for other allergens. Relief of symptoms may be delayed, but reassess the diagnosis if the patient shows no improvement after 6 months.

Subcutaneous immunotherapy is always given under medical supervision because it can cause both immediate- and slower-onset systemic reactions. These range from mild urticaria and rhinitis, through to angioedema, severe asthma and anaphylactic shock. Systemic adverse effects occur in 0.13% of patients and local adverse effects occur in 50% of patients.

Sublingual immunotherapy should be given under medical supervision for the first dose, but subsequent doses can be taken at home. Local adverse reactions to sublingual immunotherapy occur in 20 to 30% of patients, but systemic adverse effects are rare.