There are lots of good reasons not to smoke marijuana and you probably heard or read them all growing up - what you may not have heard is that marijuana, like other pollen-bearing plants, is an allergen which can cause allergic responses.

A new article summarizes research on the ways in which cannabis can act as an allergen. The article draws attention to allergic responses that may be unfamiliar to marijuana users.

Included in the article is information on case reports regarding episodes of allergic reactions, hypersensitivity and even anaphylaxis (a severe allergic reaction) to cannabis in its various forms. Among other things, cannabis pollen or cannabis smoke exposure has resulted in symptoms of allergic rhinitis (hay fever) conjunctivitis and asthma.

Allergic asthma triggered by seasonal and occupational exposure to cannabis has also been reported.

The authors still endorse more legalization, which means exposing more people to it. Their reasoning is that cannabis' legal status may create barriers for accurate and clear patient reporting, and that legal limitations may pose diagnostic challenges., which would be an odd argument to use if it were about cigarettes or cocaine.

As with other allergens, the authors say that avoidance is recommended, though now that states and the District of Columbia currently have laws legalizing marijuana in some form and four states have legalized marijuana for recreational use, avoidance to second-hand smoke is going to be difficult.

Article: Thad Ocampo, MD, Tonya Rans, MD,  'Cannabis Sativa: The Unconventional "Weed" Allergen',  Annals of Allergy, Asthma and Immunology