You Can Be Deathly Allergic to Weed

Marijuana allergies are real, and can cause everything from sneezing and itchy eyes to full-blown anaphylactic shock.

03.05.15 6:15 PM ET

Just weeks after scientists learned how to cure peanut allergies, there’s a new nut to crack: cannabis.

A paper published this week by the American College of Allergy, Asthma, and Immunology combines a wealth of research to prove that cannabis allergies are not only real, they’re potentially deadly. The condition, while “relatively uncommon,” grows increasingly more relevant as the legalization movement in the U.S. continues.

Dr. Thad Ocampo and Dr. Tonya Rans, the authors of the paper, focused specifically on allergies to cannabis sativa—the strain of marijuana known for inducing feelings of euphoria; cannabis indica, the other strain, is known for causing lethargy. Those allergic to cannabis sativa can present a variety of symptoms ranging from asthma and eczema to conjunctivitis and anaphylaxis.

Diagnosis of the allergy, which acts similarly to many others, is generally performed by a skin test. But with evidence that it may be deadly, scientists are looking for more sophisticated ways to test than using crushed buds and leaves. Some scientists are allegedly working on an invitro test for certain antibodies.

To illustrate the scope of this allergy, Ocampo and Rans zeroed in on several different case studies that show how the allergy can manifest. In one case, a 28-year-old was diagnosed with an allergy after suffering repeated sneezing, hives, swollen eyes, and cold-like symptoms when handling marijuana.

Another more serious case involved a patient who went into anaphylactic shock after eating hemp seed-encrusted seafood. The patient passed a subsequent seafood allergy test, leading to doctors to point to the hemp—a form of cannabis sativa with a lower THC content—as the source of the allergy.

While current cases of cannabis allergies are rare, the authors warn that the changing legal landscape may bring an increase in diagnosis. “With state laws allowing medical and in some cases recreational use of marijuana, there is a growing potential for legitimate personal and commercial exposure,” they write. “The evolving legal status of [cannabis], its highly prevalent use throughout the world, and the varied forms in which it is used could translate into its growing role as a clinically relevant allergen that might be encountered.”

Dr. Purvi Parikh, an adult and pediatric allergist and immunologist from The Allergy & Asthma Network, says the research should be taken seriously. “The unique nature of this allergen is that it can be inhaled or ingested,” she tells The Daily Beast. “Similar to other allergens it can cause a wide array of symptoms from runny nose, itchy eyes, hives, to breathing difficulties and full-blown anaphylactic shock.”

Parikh agrees that as the drug continues to become legalized, cases will continue to rise. “Allergies in general change over time and are related to exposure to the allergen,” she says. “With the legalization of marijuana in many states increasing, marijuana production will increase and thus will exposure to the allergen. This increased exposure will definitely lead to an increase in marijuana allergies.”

While cannabis allergies manifest much like other drug allergies, it’s the inhalation nature of the allergen that sets it apart. “Second hand smoke may cause a problem for allergy sufferers who don’t necessarily even use marijuana but are simply exposed through passive inhalation,” says Parikh. “Moreover, pollen spores from agriculture and production of marijuana can create another mode of exposure to the allergen.”

But breathing cannabis in isn’t the only danger. “Often, marijuana becomes very moldy and filled with dust mites in the way that it is stored prior to smoking,” Parikh says. “Even if patients are not allergic to cannabis itself, their mold or dust mite allergies, which are both very common, can trigger reactions or worsen reactions in combination with a potential cannabis sativa allergy.”

While the authors of the study did confirm an “increased frequency” of cases, they insist that more research is needed before the general public starts worrying about the issue.

Long story short: We’re all OK, for now.