title: Allergic hypersensitivity to cannabis in patients with allergy and illicit drug users.
abstract: BACKGROUND
  Cannabis is the illicit drug most widely used by young people in high-income countries. Allergy symptoms have only occasionally been reported as one of the adverse health effects of cannabis use.
  
  
  OBJECTIVE
  To study IgE-mediated response to cannabis in drug users, atopic patients, and healthy controls.
  
  
  METHODS
  Asthmatic patients sensitised to pollen, and all patients sensitised to tobacco, tomato and latex, considered as cross-reacting allergens, were selected from a data base of 21,582 patients. Drug users attending a drug-rehabilitation clinic were also included. Controls were 200 non-atopic blood donors. Specific IgE determination, prick tests and specific challenge with cannabis extracts were performed in patients and controls.
  
  
  RESULTS
  Overall, 340 patients, mean age 26.9±10.7 years, were included. Males (61.4%) were the most sensitised to cannabis (p<0.001). All cannabis-sensitised patients were alcohol users. Eighteen (72%) of the patients allergic to tomato were sensitised to cannabis, but a positive specific challenge to cannabis was highest in patients sensitised to tobacco (13/21, 61.9%), (p<0.001). Pollen allergy was not a risk factor for cannabis sensitisation. Prick tests and IgE for cannabis had a good sensitivity (92 and 88.1%, respectively) and specificity (87.1 and 96%) for cannabis sensitisation.
  
  
  CONCLUSIONS
  Cannabis may be an important allergen in young people. Patients previously sensitised to tobacco or tomato are at risk. Cannabis prick tests and IgE were useful in detecting sensitisation.
authors.affiliation: Direction of Public Health, Investigation, Development and Innovation, SACYL, Valladolid, Spain. aliciaarmentia@gmail.com
authors.forename: A
authors.initials: A
authors.lastname: Armentia
authors.forename: J
authors.initials: J
authors.lastname: Castrodeza
authors.forename: P
authors.initials: P
authors.lastname: Ruiz-Muñoz
authors.forename: J
authors.initials: J
authors.lastname: Martínez-Quesada
authors.forename: I
authors.initials: I
authors.lastname: Postigo
authors.forename: M
authors.initials: M
authors.lastname: Herrero
authors.forename: M
authors.initials: M
authors.lastname: Gonzalez-Sagrado
authors.forename: D
authors.initials: D
authors.lastname: de Luis
authors.forename: B
authors.initials: B
authors.lastname: Martín-Armentia
authors.forename: J A
authors.initials: JA
authors.lastname: Guisantes
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000009:adverse effects / Q000276:immunology*; D052179:Antigens, Plant / Q000276:immunology*; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology*; D002188:Cannabis / Q000276:immunology; D003429:Cross Reactions; D005260:Female; D006801:Humans; D013287:Illicit Drugs / Q000276:immunology; D007073:Immunoglobulin E / Q000276:immunology; D018551:Solanum lycopersicum / Q000276:immunology; D008297:Male; D011058:Pollen / Q000009:adverse effects; D044382:Population Groups; D012306:Risk; D012680:Sensitivity and Specificity; D012882:Skin Tests; D013030:Spain; D014026:Nicotiana / Q000276:immunology
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D013287:Illicit Drugs; D007073:Immunoglobulin E