Marijuana Can Cause Hay Fever, Other Allergic Reactions

Marijuana Can Cause Hay Fever, Other Allergic ReactionsNew review findings from a team of American scientists indicate that people who use marijuana and other forms of cannabis have commonly overlooked risks for developing mild, moderate or severe allergic reactions to the addictive, plant-based drug. Marijuana use comes with a range of potential harms that contradict the drug’s widely accepted reputation as a safe or only negligibly harmful substance. In a study review published in March 2015 in the Annals of Allergy, Asthma & Immunology, allergy and immunology researchers from San Antonio’s Wilford Hall Ambulatory Surgical Center analyzed existing evidence on the possible role of marijuana/cannabis use in triggering allergic reactions. These researchers found that there is substantial evidence for the drug as a source of relatively mild allergy symptoms and relatively severe or even life-threatening allergy symptoms.


Allergies occur when components of the human immune system treat certain substances as hostile invaders and produce a chemical response designed to protect the body. However, unlike infectious microorganisms that pose a danger to essentially all human beings, the sources of allergies (known as allergens) are commonly harmless to large segments of the population. Across the globe, widespread allergens include such things as dust, stings from insects, the pollen required for plant fertilization, dander from animal skin, dust, mold, latex rubber products and a range of medications. Allergic reactions tend to affect the skin, throat, nose, eyes, sinuses and lungs. Some individuals have relatively modest reactions to allergens, while others have serious or even potentially fatal reactions. For example, people with pollen allergies often develop a relatively minor condition known as rhinitis or hay fever. Conversely, people with insect, latex, medication or food allergies may develop anaphylaxis, a severe allergic reaction that simultaneously affects multiple parts of the body and can ultimately lead to airway restriction or blockage, complete breathing stoppage (respiratory arrest), complete heart stoppage (cardiac arrest) or a dangerous drop in blood flow known as shock. Unless treated promptly, a person with an anaphylactic allergic reaction can die within a fairly short amount of time.

Marijuana’s Allergenic Potential

All marijuana comes from the leaves and flowering tops of hemp plants known by the formal name cannabis sativa. Like all flowering plants, cannabis plants rely on the spread of pollen for fertilization. Since pollen is a common source of allergic reactions, this means that marijuana/cannabis clearly falls into the category of potential allergens. The plant’s allergenic potential is substantially increased by the fact that marijuana/cannabis pollen weighs less than many other plant pollens, floats easily and can spread a long distance from its point of origin. The main active ingredient in cannabis, THC (tetrahydrocannabinol) may also produce allergic reactions in drug consumers. Since the THC content of the typical plant has increased steeply since the 1980s, the marijuana/cannabis available today may pose a greater allergen-related risk than forms of the drug available in the past.

Is Marijuana an Allergen?

In the study review published in the Annals of Allergy, Asthma & Immunology, the Wilford Hall researchers used an analysis of dozens of previously conducted studies to explore the potential role of marijuana/cannabis as a significant allergen in humans. After completing this analysis, the researchers concluded that various forms of marijuana/cannabis exposure can trigger a range of allergic reactions. For example, people who inhale cannabis pollen can develop reactions that include pinkeye (conjunctivitis), rhinitis and the onset or worsening of asthma symptoms. People who inhale cannabis smoke can develop reactions that include rhinitis, coughing, shortness of breath and throat irritation. People who come in physical contact with marijuana/cannabis can develop allergic reactions that include skin itchiness, hives and swelling of the skin and/or mucous membranes. People who consume cannabis seeds can develop anaphylaxis. In one of the studies under review, researchers used skin prick testing to look for signs of allergy symptoms in 540 adults. These researchers concluded that the study participants who didn’t smoke marijuana had an allergy rate of 5 percent. However, marijuana smokers in the study group had an overall allergy rate of 14.6 percent; regular or habitual users of the drug had an even higher 18.2 percent rate of allergy exposure. The review’s authors also note that people previously unaffected by food allergies can go on to develop such allergies if they ever experience allergic reactions to marijuana/cannabis. 

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