What is Marijuana?

Marijuana is derived from the plant Cannabis sativa, a weed that is typically cultivated but also found to grow in the wild in some areas of the south, and Midwest. Marijuana is used for medicinal and recreational purposes, through 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, and is spread by the wind over long distances. This pollen resembles pollens from elm tree, mulberry, hop and stinging nettle, which are botanically related to marijuana.

Can you be allergic to Cannabis?

Over the past 40 years, various cases of marijuana allergy have been reported, including from smoking and ingestion of various parts of the plant, as well as from exposure to the pollen. There have been numerous reports of people experiencing symptoms of allergic rhinitis, allergic conjunctivitis, and asthma. It is interesting to note that patients, who have respiratory allergy to marijuana pollen, also can have positive skin tests to other pollen, like weeds. A study performed in Tucson, Arizona in 1980 revealed positive skin tests to Cannabis pollen in 70% of atopic people. Marijuana pollen may be a relatively common airborne pollen pollutant during the months of July and August, in the South and Midwest regions, where allergic persons become sensitized through passive inhalation of the pollen.

Is there an allergy test for Cannabis?
There is no current commercial extract for allergy test for Cannabis. Treatment typically is similar to other allergens.

Can smoking Cannabis cause respiratory problems?

The inhalation of marijuana has been known to produce respiratory disease in some, and allergic reactions in others. In addition, Marijuana smokers are at an increased risk of inhaling mold spores from the plant. Most mold spores will have little effect on people with normal immune systems, however for those with upper and lower respiratory disease, such as asthma and COPD, or chronic conditions leading to weakened immune systems, such exposure can pose a serious threat.

Can there be possible cross reactivity with other pollens and foods?

Researchers have explored the effects of the plant’s pollen, but also the potential cross-reactive effects of the protein in the bud and the flower. The “cannabis-fruits/vegetables” syndrome, is said to involve a protein labeled, Can s 3. This syndrome is caused by a lipid transfer protein (LTP) in Cannabis sativa that shares cross-reactivity with a number of different foods. It can present as localized itching and swelling of the mouth and throat area.
This is a common these, seen with a number of different foods, for example, individuals who are allergic to grass pollen, will have reactions upon eating kiwi or tomatoes. This is caused by an LTP, and the symptoms are often mild and transient.

What did we learn from this?

Marijuana may be a much more common allergen than previously thought. The pollen, the plant, and the fumes from smoking the plant, are all capable of producing allergic reactions. Symptoms vary from rhinitis, wheezing, dermatitis, abdominal issues, and even anaphylaxis. Reactions to marijuana may become more of an issue in the future given the increasing social use of marijuana, as well as its expanding medical use. It is important that marijuana exposure is addressed when assessing a patient’s exposure history.

Geraldine L. Freeman, MD: West J Med. 1983 June; 138(6): 829–831. Annals of Allergy, Asthma & Immunology, Volume 85, Issue 3, Pages 238-240,September 2000.Stokes, et al
The Journal of Allergy and Clinical Immunology, Volume 127, Issue 2, Supplement , Page AB178, February 2011

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