title: Capsaicin for allergic rhinitis in adults.
abstract: BACKGROUND
  Allergic rhinitis represents a global health problem. Non-specific nasal hyperresponsiveness is an important feature of allergic and non-allergic rhinitis. This phenomenon is believed to result from the effect of allergic inflammation on the sensory nerves that supply the upper airway mucosa. A pharmacologic agent that has proved useful in the investigation of effects of neuronal stimulation is capsaicin, the pungent component of hot pepper. Intranasal capsaicin specifically stimulates afferent nerves consisting mostly of unmyelinated C fibers and some myelinated A-delta fibers. As a result it can trigger central and axonal reflexes, the latter being putatively mediated by the release of neuropeptides. Capsaicin as a blocking agent of neuropeptides, blocks the axon reflex and may exert a curative effect on allergic rhinitis.
  
  
  OBJECTIVE
  To assess the effectiveness of capsaicin for allergic rhinitis in adults.
  
  
  METHODS
  We searched the Cochrane Ear, Nose and Throat Disorders Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2006), MEDLINE (1966 to 2006) and EMBASE (1974 to 2006). We assessed bibliographies from included studies, and contacted authors of known studies for additional information about published and unpublished trials. The date of the most recent search was January 2006.
  
  
  METHODS
  Randomised controlled trials of capsaicin for allergic rhinitis in adults were included.
  
  
  METHODS
  Three reviewers read each paper, blind to its identity. Decisions concerning inclusion were made by simple majority. We all performed quality assessment independently.
  
  
  RESULTS
  One small trial did not find evidence that intranasal capsaicin had a therapeutic effect in allergic rhinitis. A small pharmacological effect on clinical histamine dose response was found. After treatment, leukotriene levels in nasal lavage did not increase in the capsaicin group.
  
  
  CONCLUSIONS
  There is insufficient evidence to assess the use of capsaicin in clinical practice.
authors.affiliation: Guangdong College of Pharmacy, Clinical Department, Guangzhou, China, 510224. chengjing1137@126.com
authors.forename: J
authors.initials: J
authors.lastname: Cheng
authors.forename: X N
authors.initials: XN
authors.lastname: Yang
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: S P
authors.initials: SP
authors.lastname: Zhang
mesh_terms: D000328:Adult; D002211:Capsaicin / Q000627:therapeutic use*; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D012221:Rhinitis, Allergic, Perennial / Q000188:drug therapy*; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy*
chemical_list: D002211:Capsaicin