Cannabis Allergy: It’s Real!



People tend to wink at me when I say I have been to Grateful Dead concerts but never smoked marijuana.  Then I get looks of incredulity when I share that, aside from enjoying the excellent music, I really suffered from allergy symptoms during these concerts.  I would sneeze uncontrollably, my eyes would itch and water, my nose would run, and the roof of my mouth would itch.  Well, Doubters, now there is a nice review manuscript about cannabis allergy.  Yes, its real!

Here are some fun facts:

  • Cannabis sativa is a flowering plant that releases pollen in the late summer to early  autumn. The pollen grains are very buoyant, which can lead to distribution across many miles.  Wild growth does occur and Cannabis pollen is relevant in central India, urban Pakistan, southern Europe, and parts of the United States.  This Blog has had readers from all of these parts of the world.
  • The primary psychoactive component of Cannabis, delta-9-tetrahydrocannabinol (THC) may be an allergen as well.  This is especially important because, in the cultivation of Cannabis, efforts are made to increase amount of THC in the plant.  Some strains of Cannabis contain as much as 22.6% THC.
  • Regular smokers of Cannabis have reported wheezing, sputum production, and chronic cough.  However, studies have also shown that marijuana smoking can lead to acute bronchodilation and even reversal of methacholine- and exercise-induced bronchospasm. Parenthetically, this reminds me of that Peter Tosh song “Legalize It,” in which the Reggae master extolled the many perceived virtues of marijuana.  One of these was “it’s good for asthma.”  For decades I thought this lyric was just silly.  It is interesting, now, to read that marijuana smoking can temporarily relieve some aspects of asthma.
  • In people who have Cannabis allergy, marijuana smoking can trigger asthma, with symptoms such as wheeze, cough, and chest tightness.  I’m sorry, hopeful readers, but medical marijuana is not going to be indicated for the treatment of asthma.
  • Along with asthma, the inhalation of Cannabis pollen can cause other symptoms typical of allergy to a plant pollen, including runny nose, sneezing, itchy nose, watery eyes, itchy eyes, and an itchy throat.
  • Skin contact with Cannabis plant material has been associated with hives, generalized itching, and swelling around the eyes.
  • Anaphylaxis (a life-threatening allergic reaction), with such symptoms as hives, swelling, difficulty breathing, and difficulty speaking has been associated with eating hemp seeds (which come from the Cannabis plant).
  • Occupational allergy in several forms has also been described with exposure to Cannabis. One such report involved two patients who were workers in a forensics laboratory and were non-users of Cannabis.  They reported nasal and respiratory symptoms after working with marijuana and hashish (both, of course, made from the Cannabis plant).  One of these patients had more severe symptoms when handling material with especially high THC. There is also a separate report of an employee of a forensic laboratory who developed hives after handling marijuana.
  • Some people with allergy to Cannabis have also been shown to have cross-reactivity with foods, including tomato, apple, almond, eggplant, chestnut, pepper, fig, peach, banana, and citrus, with symptoms such as hives, sneezing, and, even, anaphylaxis.

This brief summary of allergy to Cannabis shows that people can be sensitive to different manners of exposure (inhaled, contact, and ingestion) to different parts of the plant (pollen and leaves).  While this allergy does not appear to be common, it is important to be aware of the possibility of Cannabis as a source of sensitivity as it is increasingly accepted in society.

Published March 7, 2015


Ocampo TL and Rans TS, Cannabis sativa: the unconventional “weed” allergen. Ann Allergy Asthma Immunol 2015 Mar;114:187-192.


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One thought on “Cannabis Allergy: It’s Real!

  1. Beth

    I have an allergy to cannabis, among many other foods.
    I think so because I have a delayed reaction food allergy to hemp seeds.
    I don’t know if I would have a reaction if I smoked cannabis though.


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