title: Anaphylaxis: still a ghost behind allergen immunotherapy.
abstract: OBJECTIVE
  Allergen immunotherapy has been shown to be an effective treatment for respiratory allergies and Hymenoptera venom allergy. However, concern regarding its potential to cause anaphylaxis may limit its use. This review aims to assess whether anaphylaxis is still a worry when administering subcutaneous (SCIT) and sublingual immunotherapy (SLIT).
  
  
  RESULTS
  Retrospective surveillance surveys and one ongoing North American prospective study have helped to characterize the incidence and risk factors for fatal and nonfatal systemic reactions to SCIT. The latest rate of very severe, World Allergy Organization grade 4, systemic reactions was similar to the previously reported rates of near-fatal reactions, that is, 1 in 1 million injections. Regarding SLIT, no fatalities have been reported. Case reports of anaphylaxis in clinical practice and in some clinical trials have been described; however, given the number of doses administered daily throughout the world, the number is very small.
  
  
  CONCLUSIONS
  Identification of possible risk factors and the introduction of safety guidelines and practice parameters have enabled the reduction in immunotherapy related systemic reactions. However, it is important that clinicians remain vigilant when administering immunotherapy and should be prepared to provide emergency treatment if required.
authors.affiliation: aSection of Allergy and Clinical Immunology, Imperial College London bNational Heart and Lung Institute, Royal Brompton Hospital, London, UK.
authors.forename: Melina
authors.initials: M
authors.lastname: Makatsori
authors.forename: Moises A
authors.initials: MA
authors.lastname: Calderon
mesh_terms: D000286:Administration, Sublingual; D000707:Anaphylaxis / Q000453:epidemiology / Q000209:etiology*; D003888:Desensitization, Immunologic / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D006967:Hypersensitivity / Q000628:therapy*; D015994:Incidence; D007279:Injections, Subcutaneous