Cannabis-fruit/vegetable syndrome: an unusual case without pollen co-sensitization

Abstract Background: Cannabis use has become increasingly popular since its legalization. In 2022, 19% of Canadians over 16 years of age report using cannabis within the past 30 days 1 . Cannabis is associated with an extensive spectrum of cross-reactivity with fruits and vegetables through a phenomenon known as cannabis-fruit/vegetable syndrome 2 . While most patients are co-sensitized with cross-reactive pollen, we present a unique case of cannabis-fruit/vegetable syndrome without birch pollen co-sensitization. Case Presentation: Since 2021, a 26-year-old female with intermittent cannabis smoking began noticing IgE mediated symptoms when eating previously tolerated fruits within the birch pollen family. Her first instance was with fresh cherries where she instantly experienced ocular/throat pruritus and generalized urticaria. In 2022, she had similar reactions to fresh peaches and raspberries. Concurrently, she began experiencing immediate ocular/throat pruritus with Cannabis sativa but not with Cannabis indica. Her fresh fruit skin test was positive to nectarine (10mm), plum (6mm), raspberry (12mm), blackberry (6mm), and both Cannabis sativa (7mm) and indica (11mm). Her environmental panel was negative to common grass, tree and weed pollens. She was prescribed an epinephrine autoinjector given her systemic symptoms. Conclusion: Multiple potential allergens including non-specific lipid transfer proteins (nsLTP), thaumatin-like protein, ribulose-1,5-bisphosphate carboxylase oxygenase, and oxygen evolving enhancer protein are thought to be contributors to cannabis allergies 3 . Of these, nsLTP is a pan-allergen found ubiquitously throughout the plant kingdom, potentially explaining cross activities between cannabis, fruits, and vegetables. Our case of cannabis-fruit/vegetable syndrome in an otherwise non-atopic individual is interesting as her skin testing showed no reaction against common pollens, specifically birch, a well-known aeroallergen to cross-react with cherries, peaches, and plums. These findings suggest the patient became sensitized to fruits through cannabis use. With increasing cannabis accessibility, more awareness in the medical community is necessary on allergic implications of cannabis use.