title: Cough reduction using capsaicin.
abstract: Chronic unexplained cough triggered by environmental irritants is characterized by increased cough reflex sensitivity, which can be demonstrated by means of inhaled capsaicin. Topical capsaicin can be used to improve non-allergic rhinitis and intestinal hypersensitivity and to reduce neuropathic pain.
  
  
  OBJECTIVE
  We established whether an oral intake of natural capsaicin (chilli) could desensitize the cough reflex and improve unexplained coughing.
  
  
  METHODS
  Twenty-four patients with irritant-induced, unexplained chronic cough and 15 controls were included in the study. For 4 weeks, the participants took capsules with pure capsaicin, and for 4 weeks, they took placebo capsules. The protocol was crossover, randomized, and double blind. Cough sensitivity during the study was evaluated by a standardized capsaicin inhalation cough test that assessed the capsaicin concentration required to reach two coughs (C2) and five coughs (C5). Participants were also administered questionnaires on cough and cough-related symptoms.
  
  
  RESULTS
  Three patients withdrew before the study end, one during the active treatment period and two during the placebo period. After treatment with capsaicin, the thresholds for C2 were higher (improved) both in patients (p < 0.020) and in controls (p < 0.0061) compared to after the placebo period. Among patients, the concentration needed to reach C2 (p < 0.0004) and C5 (p < 0.0009) increased after the period with the active substance compared to cough thresholds at baseline. The cough symptom scores improved after 4 weeks of active treatment (p < 0.0030) compared to the baseline scores.
  
  
  CONCLUSIONS
  Capsaicin powder taken orally decreased capsaicin cough sensitivity and cough symptoms. The findings suggest a desensitization of the cough-sensitive transient receptor potential vanilloid-1 (TRPV1).
authors.affiliation: Department of Internal Medicine/Respiratory Medicine and Allergology, The Sahlgrenska Academy, University of Gothenburg, Sweden. Electronic address: ewa.ternesten@lungall.gu.se.
authors.forename: Ewa
authors.initials: E
authors.lastname: Ternesten-Hasséus
authors.affiliation: Departments of Clinical Neuroscience and Rehabilitation, Physiotherapy, The Sahlgrenska Academy, University of Gothenburg, Sweden. Electronic address: ewa-lena.johansson@vgregion.se.
authors.forename: Ewa-Lena
authors.initials: EL
authors.lastname: Johansson
authors.affiliation: Department of Internal Medicine/Respiratory Medicine and Allergology, The Sahlgrenska Academy, University of Gothenburg, Sweden. Electronic address: eva.millqvist@medfak.gu.se.
authors.forename: Eva
authors.initials: E
authors.lastname: Millqvist
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000996:Antitussive Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D002211:Capsaicin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D002908:Chronic Disease; D003371:Cough / Q000139:chemically induced / Q000175:diagnosis / Q000188:drug therapy*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007509:Irritants; D008297:Male; D008875:Middle Aged; D012684:Sensory Thresholds / Q000187:drug effects; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D000996:Antitussive Agents; D007509:Irritants; D002211:Capsaicin
keywords: Capsaicin; Chronic cough; Desensitization; Sensory hyperreactivity