Cannabis sativa (hemp) is a plant that thrives in diverse environmental conditions. It is used as industrial hemp (low THC cultivars) in manufacturing of yarn, fiber, installation, and rope. Hempseed is also touted as a super food rich in protein and promoted for general good health. Higher THC cultivars are grown for medicinal use generally in the treatment of nausea, anxiety, anorexia, and pain. It is consumed as a recreational drug commonly known as marijuana. It is generally smoked, vaporized, or consumed. This industry is growing at a rapid pace particularly with the legalization and relaxation of the laws governing marijuana use.

Allergic Sensitization

Cannabis exposure is common. In the southwest United States pollination of female plants by the males of the species results in airborne dissemination with inhalation and resulting sensitization. Marijuana sensitization can also occur in workers involved in the flourishing marijuana industry. Hempseed exposures can be inadvertent as it is found hidden in foods and drinks. Allergic sensitization including the development of specific IgE (allergy antibodies) can result from inhaling, smoking, touching, and eating marijuana or cannabis allergens.

How do I know if I have a marijuana allergy?

The symptoms of marijuana allergy include many clinical manifestations depending on how a person was exposed. Contact or touching the plant can result in breaking out in rashes, hives, or swellings called angioedema. Breathing or inhaling marijuana allergens can result in nasal or ocular or eye allergy symptoms. This includes runny nose, sneezing, itching, and swelling and watering eyes. Asthma with the development of wheezing and shortness of breath also can occur. Anaphylaxis has also been reported. This most commonly occurs with hempseed ingestion.

In addition there is reported cross-reactivity between marijuana and certain foods. Cannabis cross-reacting foods that have been reported to cause allergy include tomato, peach and hazelnut. This is due to cross-reacting proteins or allergens found both in marijuana and these foods. This cross-reactivity can potentially cause serious allergic reactions. The important and relevant allergens still require research and clinical definition.

Diagnosis

There is no standard way to test for marijuana allergy, at present, and a careful history is typically used. Skin testing could be considered for patients who have histories of cannabis allergic reactions. The allergist can prepare an extract or slurry using the buds, leaves and flowers of the marijuana plant. A standard prick skin test, similar to that which is done in any standard allergy testing can then be done. While these tests are not standardized they can be used generally to predict allergic sensitization.

Summary

With the increased use of cannabis or marijuana by industry, medicine, and the general population as well as legalization there will be more reports of allergy. The symptoms although usually benign include nasal, ocular and pulmonary complaints. However life-threatening reactions have occurred but are generally limited to hempseed in marijuana allergic individuals. The definition and importance of the associated food allergies still need to be defined by research. Vigilance and awareness are paramount. Treatment is generally avoidance to insure there are no severe consequences. Hopefully it will also include immunotherapy in the future with the development of new research.