Allergic hypersensitivity to cannabis in patients with allergy and illicit drug users

Even though cannabis is one of the most widely used illegal drugs, allergic reactions have only occasionally been reported as one of its adverse health effects. A study carried out by the Department of Public Health, Investigation, Development and Innovation, SACYL, Valladolid, Spain, has looked at IgE-mediated responses to cannabis in drug users, atopic patients and healthy controls.

Carefully chosen patients included asthmatics sensitised to pollen, some sensitised to tobacco, tomato and latex (which are possible cross-reacting allergens). There were also drug users from a rehabilitation clinic, plus 200 non-atopic blood donors as the healthy controls. In total, 340 patients averaging 26 years of age were included, of which, males were the most sensitised to cannabis. All those sensitised to cannabis were alcohol users. 72% of patients allergic to tomato were sensitised to cannabis, but a positive challenge to cannabis was highest in those sensitised to tobacco. Pollen allergy was not a risk factor for cannabis sensitisation.

The results show that cannabis may be a relevant allergen in young people, and those previously sensitised to tomato and tobacco are at higher risk of sensitisation to cannabis. Prick tests and IgE were useful in detecting sensitisation to cannabis.

Source: Allergologia et Immunopathologia

First published in September 2011

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