Cannabis Allergies

As cannabis use in the US has grown, reports of allergic reactions to cannabis sativa have come up. What does this mean to the industry in general, and to growers in particular? Read on.

First, let’s look at what an allergy is. An allergy is an overreaction of the immune system to protect the body from foreign substances. This can occur due to direct contact with the allergen, or due to breathing in an allergen present in the air.

While most allergies cause some discomfort, the best solution is simply to avoid the allergen as much as possible. For someone with an allergy to sesame or cats, the idea would be to stay away from hummus and friends with feline pets. Imagine, however, the impact that an allergy to cannabis may have on someone working in a cannabis growhouse or laboratory. Beyond that, think about the impact such an allergy might have on a patient who needs medical cannabis to function.

Skin-Related Symptoms

The symptoms of a cannabis-related allergic reaction is generally twofold, primarily affecting the respiratory system and/or the skin. It may also cause irritation of the eyes (conjunctivitis).

Although contact urticaria (hives) is the primary symptom described by those with a skin-related allergic reaction, contact dermatitis (allergic rash) and angioedema (swelling) have also been experienced by those who have directly handled the plant. 

There are a couple of reasons why identifying a cannabis allergy is not easy:

  1. There may be a latency period of up to several years between the time of handling and the appearance of symptoms -- which can make documentation of the allergy difficult.
  2. Because molds and other materials may contaminate the cannabis plant, the direct cause of an allergic reaction after contact with the plant may be difficult to pin down. In some cases, it is not the cannabis plant itself causing the allergy; rather, the reaction is due to substances that are intentionally or unintentionally mixed with the cannabis.

Urticaria Research

While respiratory symptoms due to cannabis exposure have been studied rarely in recent years, even less has been discussed about skin-related reactions. The dearth of research in this area may be for one of several reasons:

  • While those who tend cannabis plants, like your employees, may have a more severe reaction to exposure, people with casual exposure may only experience mild symptoms.
  • Patient reporting may be limited due to the previously illicit nature of the substance.

In truth, however, the potential for allergic reactions to cannabis (specifically cannabis sativa) is well-documented in medical literature. IgE antibodies, which are produced by the immune system due to exposure to an allergen, have been shown to bind to peptides from the extracts of the flowers, leaves, and stems of the plant.

A small sampling of studies even supports the fact that cannabis can lead to skin irritation, not just respiratory issues. For example, more than one study has discovered that some lab technicians have developed a delayed contact urticaria response (confirmed by skin prick testing) to the resin and plant parts of cannabis. In addition, another study analyzed samples from a forensic lab and confirmed a histamine release, causing an IgE-mediated allergic response to cannabis, causing both respiratory and skin-related symptoms. 

If Your Employee Has Cannabis Allergy

Unfortunately, there is currently no standard testing methods used to diagnose an allergy to cannabis; however, a skin prick test can be done to determine sensitivity to the plant. To conduct this test, an allergist would need to actually harvest a cannabis plant and use its buds, leaves, and flowers to prepare an extract or slurry, which could be inserted under the skin and watched for the appearance of any skin-related symptoms.

If you find that one of one of your employees does have a cannabis-related allergy, the treatment options depend on the level of exposure and the symptoms.

  • The employee can take antihistamines to manage symptoms and reduce discomfort. Allergy shots and drops are not currently available for cannabis allergies.
  • Those with a severe allergy should consider moving to a different position; if they are at any risk of accidental exposure, however minimal, they should make sure to carry an epinephrine injection at all times. 
  • Reduced exposure is the primary treatment for a cannabis allergy. Realistically, the employee will need to avoid ingesting, smoking, or touching the plant to avoid triggering an allergic reaction.
  • In cases where exposure is impossible to avoid (e.g., lab workers, cannabis farmers, those living in areas with large numbers of cannabis plants), using personal protective equipment (PPE) is essential. Your PPE options should first and foremost include wearing gloves with arm protection, or gloves with an extended cuff.
  • As with any job that requires donning gloves for an extended period of time, consider applying a pre-barrier cream to the skin in order to limit the risk of dermatitis.
In some circumstances, a respirator may be helpful in limiting symptoms. To determine whether your workplace requires a respirator, contact an industrial hygienist in your area.