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 and pain. It is consumed as a recreational drug commonly known as marijuana. It is generally smoked, vaporized or eaten. This industry is growing at a rapid pace particularly with the legalization and relaxation of the laws governing marijuana use.
Nobody likes allergies, right? In fact, everyone I know absolutely despises them. According to the American College of Asthma, Allergy, and Immunology, more than 50 million Americans suffer from allergies each year. Cumulatively, that’s a huge number of people who will experience some sort of allergic reaction at a point in their life, whether it be to a particular variety of food, pollen, mold, or perhaps a more specific irritant such as cats.
What if, however, you found yourself with an allergic reaction to your job, or to something you greatly enjoyed, or, even worse, to something that you need? Stories of cannabis allergies have been emerging at a growing rate since legalization and reveal that they can frequently strike down budtenders, recreational consumers, and medical patients with a variety of symptoms.
For example, here is one of the typical communications we receive on the topic:
I have tried one medical marijuana, and I used it for about 12 days. I found I was allergic to it. Then just to verify it was the hemp, I smoked a little, and got the same reaction. Bad allergies, total constant nasal drip, watery eyes, stuffy head. My eyes would even burn at times. Is there something equivalent for pain, that will not give me such bad effects? Or is there somewhere I can investigate further? I think it really does some of my arthritic pain. Thank You.
Given the increasing frequency of these stories about people being allergic to cannabis, and the apparent need for more information, we felt it necessary to investigate the matter further.
Allergy and 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 can result from inhaling, smoking, touching, and eating marijuana or cannabis allergens.
Can You be Allergic to Weed?
Allergies are an immune overreaction by the body attempting to protect the respiratory system from outside invaders. The antibodies produced by the body succeed in keeping the perceived foreign invaders out, but also cause the symptoms characteristic of allergic responses. Pollen, the most common allergen, is a powder released by trees, grasses, and weeds to fertilize the seeds of neighboring plants. Mold, somewhat differently, is a spore that grows on rotting logs, dead leaves, and grasses. While dry-weather mold species exist, many types of mold thrive in moist conditions. Perhaps not so shockingly, given that both these allergens are associated with cannabis, researchers in Belgium recently published an article entitled “Emerging allergens: Cannabis.” The researchers focused in particular on cannabis sativa, one of the two species we all know colloquially as marijuana. They found that the plant can cause a number of allergic symptoms such as allergic rhinitis (hay fever), conjunctivitis (pink eye), skin rashes, and asthmatic symptoms when smoked, inhaled, or chewed. Yikes! On reading that our interest was piqued. This is a thing; an actual thing!
Allergic Reactions to Edibles
Marijuana edibles have become more available for medicinal use as well as places where they are legal for all users. While it is rare, there are reported cases of anaphylaxis reactions with eating hemp seeds.2 The symptoms can include ocular symptoms, rash or hives, swelling, shortness of breath, and difficulty speaking.
Marijuana allergy symptoms
Marijuana allergies have become more common in recent years. Although the plant is known for anti-inflammatory properties, cannabis can cause a number of symptoms if it’s inhaled. If you smoke and you have a weed allergy, you may experience:
- red eyes
- watery eyes
- hay fever
- runny nose
Cannabis allergies can also resemble contact dermatitis if the plant is tampered with or handled. In a 2007 study evaluating marijuana allergy symptoms, a skin prick test revealed that cannabis can cause specific skin irritation. Some of the most common irritations include:
- inflamed, red skin
- dry, scaly skin
In more severe cases, an allergic reaction to cannabis can cause anaphylactic shock, a life-threatening condition that causes your blood pressure to suddenly drop and your airways to close. If left untreated, a marijuana allergy could be fatal.
What causes cannabis allergy?
First off, it is important to differentiate between true cannabis allergy and allergic reactions to substances found in cannabis that are not endogenous to the plant, such as moulds or dust mites. It is well known that poorly grown and poorly stored cannabis can contain both, and both are well known to cause strong allergic reactions in many individuals.
There have been several cases of severe reactions occurring in individuals who smoke mouldy weed, and at least one death has been attributed to it (although importantly, the individual in question was severely immune-compromised due to recent surgery).
However, cannabis allergy itself is a specific allergy to a substance or substances contained within the plant. In fact, there are several substances that may represent a risk to sensitive individuals, and it may be that different cases of cannabis allergy occur in response to different substances.
Histamine is an organic nitrogenous compound, and is synthesised in the body by the decarboxylation of the amino acid histidine. Histamine has a vital role in regulating local immune response. When allergens are present at certain key areas of the body (such as the mucous membranes), histamine is released by mast cells or white blood cells known as basophils in a process known as degranulation.
Degranulation is a mechanism whereby certain cells involved in immune response release cytotoxic compounds that destroy invading microorganisms such as allergens. When such allergens enter the body, the molecules of the free-floating antibody protein known as immunoglobulin E (IgE) bind to Fc receptors found on the surface of the mast cells and basophils.
The allergens then bind to the IgE, and the cell begins to release histamine. This triggers the inflammatory response and increases the permeability of the capillaries to allow certain white blood cells and proteins to directly attack the invading pathogens.
This is the physiology behind how the body deals with allergens. The immune response is important for maintaining health, especially against foreign bodies. However, allergies are often considered to be an overreaction of the immune system, producing histamine in the absence of an actually threatening foreign substance. Different substances in cannabis (and in other plants) trigger this sensitivity in certain individuals, resulting in symptoms otherwise referred to as hay fever.
Different cannabis allergens
The most likely allergen to cause a reaction is cannabis pollen. This is typically only produced by male plants, but can also be produced by females that express hermaphroditic male flowers (and in severe cases of hermaphroditism, there can be a significant amount floating in the air).
Cannabis and hemp pollen has been shown to cause allergic reactions in several studies, and individuals who show sensitivity to it typically also are sensitive to pollen from other plants. A study conducted in 2000 in the U.S. Midwest showed that 73% of the subjects were sensitive to cannabis pollen, and that each of those individuals was also sensitive to local plants such as ragweed, Russian thistle and cocklebur.
However, this does not explain the cases of cannabis allergy that are caused by female plants with no signs of hermaphroditism. In these instances, something else is clearly to blame, and scientists have pinpointed almost a dozen possible culprits.
Most of the possible allergens found in cannabis are proteins, and many of them have been found in other plants and have been confirmed to be allergens. Several studies have pointed to the existence in cannabis of a particular type of protein known as a lipid transfer protein (LTP), which are often implicated in allergies.
Cannabis LTP, the possible key to the allergy
Several studies into cannabis allergy have pointed to the existence of an LTP or LTPs present in the growing plant. One study published in 2007 actually reported that a unique LTP had been isolated in cannabis, which was subsequently named Can S3. In at least one study, patients have shown specific sensitivity to the substance described as Can S3 when undergoing skin prick tests and other immunological test. However, as Can S3 sensitization is not absolute, other cannabis allergens probably play a role.
In a pertinent study published in the Annals of Allergy, Asthma & Immunology in 2013, the researchers did not find any evidence of an LTP protein present in cannabis. However, they found strong evidence of other common allergens.
Risk factors of a cannabis allergy
Your body views allergens as a threat. While it works to protect against foreign bacteria and threats, your immune system will also cause a number of reactions or allergic responses. There are a few risk factors that could increase your likelihood of developing a cannabis allergy.
Marijuana allergies can become more prevalent if you’re allergic to a food or substance with similar protein properties. This is also called allergy cross-reaction. Some foods with similar allergen properties as the cannabis plant are:
- almonds and chestnuts
Increased cannabis exposure can also make you more likely to develop a sensitivity to the plant. This is more common in areas where marijuana is grown. Pollen from the cannabis plant can trigger allergen symptoms. As a result, marijuana sensitization has increased since its legalization.
Increased THC content
Marijuana is dioecious, meaning that it grows male and female plants. Marijuana growers specifically prefer female plants because they grow more buds, which are the flowers that can be smoked recreationally. Male flowers typically aren’t used because they have little buds.
The more buds grown from the plant, the more THC is produced. THC — scientifically known as tetrahydrocannabinol — is the chemical found in marijuana flowers that creates the euphoric high. Growers isolate female marijuana plants from being pollinated in order to control THC production. When grown in bulk, THC content increases and can affect your sensitivity to the plant.
Diagnosing a marijuana allergy
In order to identify an allergy, a doctor or allergist will perform a skin prick test. This test can show whether or not you’re sensitive to a particular substance.
During this procedure, your doctor will prick your arm or back with a small amount of an allergen to the area. If you’re allergic, your body will react and trigger an allergic response such as swelling or itching within 15 to 20 minutes. If you aren’t allergic, you’ll show no symptoms.
You can also use a blood test to test for allergies. The most common allergy blood test is the immunoCAP test. Other allergy blood tests include the enzyme-linked immunosorbent assay (ELISA) and the radioallergosorbent (RAST) blood test.
These blood tests look for antibodies that are specific to a certain type of allergen. The more antibodies in your bloodstream, the more likely you are to be allergic to a specific substance. A blood test is considered a safer option because it lowers your risk of having a severe allergic reaction. However, results aren’t available for several days.
Preventing an allergic reaction
The best way to prevent having an allergic reaction to marijuana is to avoid it. If you’re using medical marijuana, smoking it recreationally, or consuming edibles, doctors recommend you stop to avoid a severe reaction.
If you work with the cannabis plant regularly for work, doctors recommend wearing gloves, face masks, and using allergy medication to help reduce or prevent symptoms. Doctors also recommend carrying an inhaler in case the marijuana pollen affects your breathing
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.