METHODS: 11 patients who presented to an ambulatory allergy clinic with cannabis (marijuana or hempseed) allergy were evaluated. Skin prick test with a cannabis extract was performed to confirm diagnosis. A questionnaire was administered to document the routes of exposure, timeline of symptoms development, reaction types and cross-sensitizations.
RESULTS: The mean age of the patients were 27 years (range 18 – 37), and the mean duration of cannabis use is 7 years (range 1 – 13). 3 patients had reaction to cannabis with first exposure. 3 patients reported GI symptoms (abdominal pain and vomiting) with ingestion of marijuana, and 2 of these 3 patients also reported the same reactions with hempseed ingestion. 8 patients reported rhinitis and ocular symptoms with smoking marijuana, and 7 patients reported urticaria and pruritus with touching cannabis. Two patients developed GI symptoms and anaphylactic reaction to ingestion of hempseed after 1 – 2 years of smoking marijuana. One patient also have allergic reaction to tomato which is known to cross-react with cannabis. One patient reported exercise-induced anaphylaxis dependent on cannabis ingestion and smoking.
CONCLUSIONS: Cannabis allergy symptoms vary depending on the routes of exposure. Anaphylactic reactions to ingestion of hempseeds can develop after marijuana exposure. Cannabis can be a co-factor in food-dependent exercise-induced anaphylaxis.