ICR 2019: Asthma, Allergy, Cannabis

Cannabis Sativa Exposure and Sensitization: Relationship to
Asthma, Dermatitis and Food Allergy

William S. Silvers, M.D., Nathan Rabinovitch, M.D. MPH

University of Colorado School of Medicine, Aurora, CO; National Jewish Health, Denver, CO.

First and second-hand cannabis exposure has increased
substantially and is expected to continue to increase as personal cannabis use
becomes legalized in more states and countries. Health effects of exposure may
be related to allergic sensitization as a number of reports have found
associations between cannabis exposure and asthma, allergic rhinitis, contact dermatitis
and urticaria, as well as reported anaphylaxis. 
In this context, it is to be expected that with greater frequency and
magnitude of exposure, the prevalence of cannabis sensitization will increase over
time in predisposed atopic children and adults. European studies have reported
on a cannabis fruit-vegetable syndrome, occurring when the cannabis allergen
Can s 3, a lipid transfer protein (LTP), cross-reacts with various plant
homologues. Food reactions often manifest as a severe form of oral allergy
syndrome (OAS) because LTPs are resistant to gastric proteolysis once swallowed
unlike classical OAS from the birch allergen Bet v 1.

Regular cannabis use has been associated with bronchitic
symptoms such as chronic cough, wheeze, and increased sputum production, but,
to date, marijuana smoking has not been associated with an increase in emphysema
or lung cancer. These negative studies however
are limited by the fact that most marijuana smokers are younger than tobacco
smokers and many also smoke tobacco. As such, these studies cannot definitively
rule out associations with long-term use of marijuana especially in those who
have no concomitant history of smoking tobacco.

The prevalence and spectrum of adverse reactions, allergic
and non-allergic, will be addressed with individual case presentations and results
from population surveys.  Patients,
parents and their physicians should be aware of the potential link between
cannabis exposure, the initiation of new food allergies and worsening of
pulmonary and dermatologic disease so that recommendations for decreasing first
and second-hand cannabis exposure can be implemented in affected adults and
children.

References: 

1. Silvers WS, Bernard T:  The Spectrum and Prevalence of Reactions to Marijuana in a Colorado Allergy Practice.  Ann Allergy Asthma Immunol.  2017; 119:570-71

2. Rabinovitch, N, Leung DYM, Covar, R: The Highs and Lows of Marijuana
Use in Allergy.  Ann Allergy Asthma
Immunol. 2018, 121:14-17.

Accepted to the Institute of Cannabis Research Conference, Pueblo, CO March 23-25, 2019