Can You Be Allergic to Cannabis?
As cannabis becomes more mainstream and restrictions around it decrease, both new and experienced users are learning more about how the human body reacts to this plant. People with seasonal allergies, plant allergies, or food allergies often wonder: is it possible to be allergic to cannabis too? And if so, what are the signs and symptoms?
What We Know About Cannabis Allergies
Although there hasn’t been a lot of research on this topic yet, we do know that cannabis allergies exist. The plant has long been surrounded by myths and misconceptions, with many side effects attributed to it over the years—some true, some completely made up. However, the possibility of being allergic to cannabis is not an exaggeration or a scare tactic, nor does it mean the plant is inherently harmful or lacks therapeutic benefits. Cannabis is like any other plant and can cause allergies in some people who use it.
Let’s look at the available research to better understand the mechanisms behind cannabis allergies.
Lipid Transfer Proteins
Recent studies have identified lipid transfer proteins as potential allergens in cannabis. These proteins are commonly found in plant-based foods and pollen and can trigger allergic reactions in the human body by causing an increased production of antibodies.
In a March 2019 study published in the journal Annals of Allergy, Asthma & Immunology: Practice, 120 patients with cannabis allergies and 62 healthy controls were given cannabis extract in three ways, including a skin prick test. The extract contained high levels of Can s 3, a nonspecific lipid transfer protein prevalent in cannabis. The study found that about 80% of patients with cannabis allergies, and 72% of those with anaphylactic reactions, were sensitive to the Can s 3 protein.
In short, this research suggests that while lipid transfer proteins are not the only allergens in cannabis, they play a significant role in triggering allergic reactions.
Cross-Reactivity
Other studies examining sensitivity to lipid transfer proteins among cannabis-allergic patients have shown similar results. According to a December 2017 study published in a French clinical pulmonology journal, there is often cross-reactivity with plants containing similar proteins. Cross-reactivity occurs when a person has an allergic reaction to similar proteins found in other substances. About 45% of cannabis-allergic patients in a study published in the Journal of Allergy and Clinical Immunology also reported allergic reactions to plant-based foods.
A 2013 study in the International Archives of Allergy and Immunology looked at reactions to lipid transfer proteins in 21 patients with food allergies. Twelve of them also had cannabis allergies, and all experienced more severe food reactions than those without cannabis allergies. A 2008 study in the same journal tested 32 participants for allergies to lipid transfer proteins, as well as tomatoes, peach skin, and pollen extracts. People sensitive to tomato allergens also reacted to cannabis, and there was significant cross-reactivity between peach skin and cannabis. These studies further confirm that lipid transfer proteins play a central role in cannabis allergies and may cause cross-reactivity with other food allergies.
Terpenes
If lipid transfer proteins aren’t the only source of cannabis allergies, what else matters? You may have heard a lot about terpenes lately—they’re responsible for the aroma and flavor of cannabis and some other plants. Terpenes, like the main cannabis compounds CBD and THC, have a wide range of medical benefits. However, they may also partially cause allergic reactions to cannabis in some users.
For example, the terpene linalool can cause allergic reactions when used as an oxide or exposed to air. In a 2010 study, patches with different concentrations of linalool were applied to the skin of 1,151 patients with dermatitis. A positive reaction was found in 5-7% of patients. In a similar 2016 study, linalool oxide and limonene oxide—other significant cannabis terpenes—were tested on a group of 2,900 dermatitis patients, and 281 of them had an allergic reaction to one or both terpenes.
These results don’t mean terpenes cause most cannabis allergies, but they are definitely linked to allergic reactions, especially skin reactions.
Signs and Symptoms of a Cannabis Allergy
Depending on the type of exposure (skin contact, inhaling pollen, etc.), cannabis allergies can cause a wide range of symptoms, most of which are typical for other allergies.
In a report by Canada’s CTV News about the rising number of cannabis allergy cases after legalization, Toronto immunologist and allergy expert Dr. Gordon Sussman said that increased access to cannabis will inevitably lead to more allergic reactions.
Dr. Sussman found that the number of patients sensitive to cannabis has increased over the past 10 years, and he is actively studying the phenomenon of undiagnosed cannabis allergies to raise awareness and better prepare doctors.
“If you look at a study conducted in Colorado, about 10% of people passively exposed to cannabis smoke developed allergy symptoms,” Dr. Sussman explained. In the same CTV report, he added that skin contact with the plant can cause irritation, ranging from mild itching to rashes and swollen eyes. Smoking cannabis or inhaling its pollen can lead to sneezing or a runny nose, as well as wheezing, shortness of breath, and asthma-like symptoms. Patients who eat cannabis seeds or other cannabis products may also experience anaphylactic reactions.
What to Do If You’re Allergic to Cannabis
Dr. Sussman told CTV News that “the only effective way to deal with a cannabis allergy” is to avoid it. The good news is that if you develop a cannabis allergy, standard allergy treatments are usually enough to relieve or eliminate your symptoms.