Like other pollen-bearing plants, hemp (Cannabis sativa), from which the grass that smokers use come, can cause allergic reactions. An article published in 2015 by a Canadian team in the Annals of Allergy journal, Asthma and Immunology, decrypts for the first time the allergenic process of cannabis, thanks to the analysis of available scientific data. Information largely unknown to most cannabis users… and others.
Canadian researchers have identified the various symptoms associated with cannabis exposure that caused allergy, hypersensitivity, and sometimes even anaphylactic shock (severe life-threatening allergy). According to this study, the first reported case of cannabis allergy occurred in 1971: a 29-year-old woman had anaphylactic shock after smoking cannabis for the first time. Among the respiratory symptoms, allergic rhinitis and allergic asthma are among the most common cases.
According to a study conducted in 2014 by a Belgian team, immediate skin symptoms have been observed in cannabis users: in particular, urticaria and angio-edema following contact of the plant with the skin or mucous membranes (lips and eyelids). Respiratory symptoms also, such as rhinoconjunctivitis and palpebral angioedema have also been observed.
Allergies affect up to 1% of cannabis smokers, reports the Belgian study. But these are not the only ones concerned. Anaphylaxis has been observed after ingesting cannabis seeds or drinking marijuana tea, the researchers say. And even among people who have never used cannabis! “The airborne allergen may well be a potential cause of passive sensitization that has recently been suggested in a 5-year-old child,” the study wrote.
In recent years, an increasing number of cannabis allergy sufferers were found to also suffer from proven cross-allergies. This syndrome, called the “cannabis-fruit/vegetable syndrome”, seems to mainly involve s3, a protein. Being a stable allergen that resists heat and remains functional in the gastrointestinal tract, it can lead to generalized reactions such as urticaria, breathing difficulties and anaphylaxis.
The plant-related food allergy linked to this protein mainly concerned peaches, apples, cherries, hazelnuts, tomatoes and sometimes citrus fruits such as orange and grapefruit. “Since then it has been shown that cannabis sensitization could eventually lead to cross-reactivity with cereals, alcoholic beverages (beer and wine), Hevea latex and tobacco,” the researchers say.
The Canadian authors point out that the legal status of cannabis creates barriers to case reporting and diagnosis. “As cannabis legislation is evolving in the United States and other countries, it is important for doctors to educate their patients about allergic risk,” the researchers conclude.