How to diagnose and treat cannabis allergies?

As medicinal and recreational cannabis becomes legal and more popular in more places, clinicians must learn how to diagnose and manage cannabis allergies, an international problem. overview and consensus document recommended.

Allergic reactions to cannabis include rhinitis, conjunctivitis, asthmaskin reactions and anaphylaxis with hemp seeds. Exposure can come from smoking, food, inhalation of cannabis pollen or smoke, and skin contact, and includes occupational allergies.

“Cannabis can cause type 1 and type 4 allergic reactions. Officially recognized allergens include a pathogenesis-related class 10 allergen, profilin, and a non-specific lipid transfer protein,” said the lead author. Isabel J. Skypala, PhD, RD, of Imperial College London. , London, UK, and colleagues write in Allergy.

“Cannabis is the most widely used recreational drug in the world. Cannabis-sativa and Indian Cannabis have been selectively bred to develop their psychoactive properties. The growing use in many countries has been accelerated by the COVID-19 pandemic,” they add.

Diagnosing a cannabis allergy is difficult

About 192 million people — 3.9% of the world’s population — use medical or recreational devices Cannabis-sativa (Can s), but its illegality has hampered research and posed diagnostic problems.

Clinical history is the most important test for immunoglobulin E (IgE)-dependent cannabis allergy, but patients may not admit to using cannabis illegally. The authors recommend creating a standardized intake form with cannabis-related questions.

No commercial extracts are available for clinical testing, so non-standardized prick-prick testing with cannabis buds, leaves, or seeds may be the only option, if available. But cross-reactivity in patients sensitive to pollen and plant foods can render positive sting-prick results clinically insignificant.

Although skin tests using pre-prepared cannabis extracts may be better standardized and designed to concentrate known allergenic components, they may not be available in clinics and, as with prick-prick tests, patient sensitization may affect the results. No commercial specific IgE (sIgE) antibody test for Cannabis-sativa Where Indian Cannabis are available for clinical use.

The authors recommend an initial test with skin tests using native extract and/or quantification of hemp sIgE, and, if necessary, calculation of the sIgE/total IgE ratio, molecular diagnosis and/or basophil activation test or passive mast cell activation test, if available. Negative results indicate that cannabis allergy is very unlikely.

They do not advise challenging provocation with inhaled cannabis, due to possible legal issues and the risk of inhaled cannabis vapors triggering non-specific hyperreactivity without confirming allergy. And the reliability of oral provocations to edible cannabis products or hemp seeds and sensitization to other allergens, including molds, pollens and foods, is unknown.

Continuing education and research are necessary

Cannabis allergy could become a significant public health problem, the authors write. More real data is needed, testing and treatment protocols need to be developed, and providers need to learn how to communicate with their patients so they can provide optimal care.

The cannabis allergy article is a first step. To help educate healthcare professionals and foster future research on cannabis allergy, members of the American College of Asthma Allergy and Immunology (ACAAI), European Academy of Allergy and Clinical Immunology ( EAACI) and the Canadian Society of Allergy and Clinical Immunology (CSACI) formed the Cannabis Allergy Interest Group (CAIG).

To collect more real-world data, CAIG plans to establish a registry and biobank to collect samples from Europe, the United States, and Canada, and to develop international diagnostic and management guidelines. cannabis allergies. The group is also conducting a survey of members of its three societies on knowledge, attitudes and practices related to cannabis allergy.

Adapt the treatment to the patient’s goals

The only current treatment for cannabis allergy is avoidance, and when this is not possible, as with occupational exposure, the authors recommend treating symptoms with antihistamines, intranasal and inhaled corticosteroids, antihistamines ophthalmic/mast cell stabilizers or self-injectables. epinephrine.


Dr. David Lo

David Lo, MD, PhD, Senior Associate Dean for Research and Distinguished Professor in the Division of Biomedical Sciences at the University of California, Riverside School of Medicine, said Medscape Medical News that allergies can occur to almost any organic material, including those made from plants, as in the case of food allergies.

“Most people don’t develop allergies to these things, but when they do, it’s usually to a protein or fragment of the material,” he said in an email.

“Allergies to extracts from plants such as cannabis can be avoided if the primary goal is to provide an active ingredient such as THC or related compounds,” explained Lo, who was not involved in the development of the product. consensus document. “In this case, a more highly purified version – or even better, a synthetic version – would be used, so the protein that is the target of the allergy would be missing.”

“On the other hand, if the goal is to deliver an extract where the active component is known to be a protein or protein fragment, then the problem is more difficult, and it might be necessary to synthesize a recombinant protein that does not doesn’t have the allergen in it,” he added.

Extreme purification from raw plant material is possible but often difficult to achieve, Lo said.

“That’s why you see so many food labels stating that the food was prepared in a factory where nuts or peanuts are processed. Allergens can be detected by the immune system and potentially trigger anaphylaxis, at extremely high concentrations. weak.

“However, in the case of cannabis, the desired active ingredient is unlikely to be a protein; it is most likely compounds such as THC or related chemicals,” he noted. “The synthetic versions are therefore the ideal solution for people with known allergies, but they are probably very expensive.”

Awareness and ongoing challenges

Tiffany Owens, MD, assistant professor of allergy and immunology at Wexner Medical Center at Ohio State University in Columbus, called the consensus document an extensive and important review of available literature that summarizes up-to-date information on cannabis allergy.



Doctor Tiffany Owens

“Many non-allergists may not be aware that cannabis allergy is a possible problem,” she said in an email. “I hope this report will help expand differential diagnoses to include cannabis allergy where appropriate and help patients receive appropriate advice and treatment.

“It remains difficult for some clinicians and patients to discuss cannabis allergy due to concerns about the legality of cannabis acquisition, possession and use; clinicians’ lack of knowledge about cannabis use and patients’ reluctance to discuss their cannabis use,” Owens, who was also not involved in the study, added.

“It will be important to continue to support clinicians and patients with evidence-based information about the risks and benefits of cannabis,” she said. “I will be interested to see what future allergy testing modalities will be available.”

Skypala and several co-authors report financial relationships with the pharmaceutical industry. Lo and Owens report no relevant financial relationship. The International Cannabis Allergy Collaboration of the American College of Allergy, Asthma and Immunology, the Canadian Society of Allergy and Clinical Immunology, and the European Academy of Allergy and Clinical Immunology provided financial support.

Allergy. Published online January 31, 2022. Full Text.

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