Immunomodulatory therapy

Specific allergen immunotherapy (desensitisation)

Specific allergen immunotherapy is effective in the management of rhinitis and asthma and can achieve a durable remission of allergic symptoms.^{37, 38, 39 [Level I]} Evidence from a randomised clinical trial suggests that it may reduce the risk of childhood rhinitis progressing to asthma.^{14, 15 [Level II]}

This treatment should be considered only when there is evidence that allergic rhinitis is predominantly due to exposure to a single allergen, and where it is not possible to avoid the allergen (e.g. pollens, house dust mite, occupational allergens). It should be considered in consultation with an allergist.

Oral (sublingual) and injectable (subcutaneous) forms of immunotherapy are available:

• Subcutaneous allergen immunotherapy involves a course of injections given weekly to monthly over 2–3 years. It is well tolerated in adults and children when administered and supervised by an allergist.⁴⁰ Potential adverse effects include injection-site reactions, sneezing, bronchospasm, urticaria and anaphylaxis. Subcutaneous immunotherapy can only be attempted while asthma symptoms are well controlled. The risk of a fatal allergic reaction is increased in patients with marked airflow limitation (e.g. when forced expiratory volume in one second is less than 70% of the predicted value).⁴¹ Immunotherapy is contraindicated in patients with severe or unstable asthma and those using beta blockers.
• Sublingual immunotherapy involves daily self-administration by the patient at home, and is relatively expensive. There is limited evidence for efficacy of sublingual immunotherapy in children. Since immunotherapy should be prescribed by an allergist or specialist physician with specific training in allergy, access to immunotherapy as a treatment option is often limited.

Anti-immunoglobulin E (IgE) therapy

Monoclonal anti-IgE antibody therapy (omalizumab) also has been reported to be effective in controlling symptoms of allergic rhinitis in patients with concomitant asthma and allergic rhinitis.⁴² The feasibility of using this option may be limited by cost, because omalizumab (Xolair) is not listed on the Pharmaceutical Benefits Scheme.

Practice points

• Discuss immunotherapy early in the course of allergic rhinitis, if suitable.
• Explain to patients that immunotherapy:
  • has not been shown to be effective in patients with multiple allergens, so is most likely to benefit those with a well-defined single allergen (e.g. pollen, house dust mite, cat allergens) 
  • offers no benefit if triggers are substantially non-allergic 
  • can cause local and systemic adverse effects.