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Marijuana Allergy

Allergy to Cannabis

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Updated April 23, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Marijuana is derived from the plant Cannabis sativa, a weed that is typically cultivated but occasionally found to grow in the wild. Marijuana is consumed for its medicinal and recreational purposes through the inhalation of smoke from burning plant matter, as well as through oral ingestion of various parts of the plant. Cannabis sativa also produces large amounts of pollen, typically during the summer months, that is spread by the wind over long distances. This pollen microscopically resembles Nettle, a weed pollen that commonly causes allergic symptoms. Over the past 40 years, various cases of marijuana allergy have been reported, including from smoking and ingesting various parts of the plant, as well as from exposure to the pollen.

Cannabis Pollen Allergy

There have been numerous reports of people experiencing symptoms of allergic rhinitis, allergic conjunctivitis, and asthma as a result of being exposed to Cannabis pollen. A study performed in Tucson, Arizona in 1980 revealed positive skin tests to Cannabis pollen in 70% of atopic people. A more recent report from 2008 described a woman with nasal and eye allergy symptoms after working in a research laboratory with exposure to marijuana plants.

While there is not currently a commercially available test for Cannabis pollen allergy, research laboratories could create a RAST allergy test, and many allergists could use pollen and other plant parts to make a homemade skin test extract. Treatment of allergy caused by Cannabis pollen would be identical to that for other pollen allergies.

Marijuana Smoke Allergy

Smoking marijuana, especially the Cannabis buds and flowers, has also been reported to cause allergic reactions, including allergic rhinitis, asthma, urticaria, angioedema and anaphylaxis. Marijuana smoke would be expected to contain Cannabis plant and pollen allergens, and Δ9-tetrahydrocannabinol (THC), which may also trigger allergic reactions.

A report of 17 people with allergic reactions to marijuana smoke was published in 2012, all with positive skin tests to a homemade allergy extract made from Cannabis buds and flowers. The study did not address how these people were treated, and other than avoidance of smoking marijuana, there would not be another treatment option currently available. While allergen immunotherapy (allergy shots) with Cannabis pollen could theoretically be helpful for marijuana allergy, this hasn’t been studied to date.

Other reactions from smoking marijuana have resulted from contamination of the marijuana with Aspergillus, a mold that commonly causes allergic diseases. Aspergillus-contaminated marijuana has been reported to have caused allergic bronchopulmonary aspergillosis (ABPA) and hypersensitivity pneumonitis (HP), in addition to allergic rhinitis and asthma.

Allergy to Eating Marijuana

It's also possible to consume marijuana orally in the form of herbal teas and in baked goods. Allergic reactions have also been reported from eating marijuana, including urticaria and angioedema. Cross-reactivity has been found between marijuana and other foods, including peach and tomato, similar to that seen in oral allergy syndrome. Therefore, it is possible that allergies to other pollens and fruits could predispose a person to developing an allergy to eating marijuana. The treatment of allergy from eating marijuana is the same as that for other food allergies.

Read more about other forms of smoke allergy: mesquite wood smoke allergy and cigarette smoke allergy.

Sources:

Tessmera, Berlin N, Sussman G, et al. Hypersensitivity Reactions to Marijuana. Ann Allergy Asthma Immunol. 2012;108: 282-284.

Mayoral M, Calderon H, Cano R, et al. Allergic Rhinoconjunctivitis Caused by Cannabis sativa Pollen. J Investig Allergol Clin Immunol 2008; Vol. 18(1): 71-77.

Freeman GL. Allergic Skin Test Reactivity to Marijuana in the Southwest. West J Med 1983 Jun; 138:829-831.

Kurup VP, Resnick A, Kagen SL, et al. Allergenic Fungi and Actinomycetes in Smoking Materials and Their Health Implications. Mycopathologia. 1983 Apr 22;82(1):61-4.

Llamas R, Hart R, Schneider NS. Allergic Bronchopulmonary Aspergillosis Associated with Smoking Moldy Marijuana. Chest 1978;73;871-872.

DISCLAIMER: The information contained in this site is for educational purposes only, and should not be used as a substitute for personal care by a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition.

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