Cannabis allergies, their symptoms, identification and treatment

Are cannabis allergies a real thing? How do you know if you have it and how do you treat it?

What are cannabis allergies

Allergies are an excessive immune response by the body in an attempt to protect the respiratory system from outside invaders. Antibodies produced by the body succeed in preventing the entry of perceived foreign invaders, but also cause the symptoms characteristic of allergic responses. Pollen, the most common allergen, is a powder released by trees, grasses and weeds to fertilise the seeds of neighbouring plants. Mould, somewhat differently, is a spore that grows on decaying trunks, dead leaves and grasses. Although there are dry weather mould species, many types of moulds thrive in wet conditions.

It is perhaps not so surprising that these two allergens are associated with cannabis. Belgian researchers recently published a paper entitled “Emerging allergens: Cannabis“. The researchers were particularly interested in cannabis sativa, one of the two species we all know 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.

Cannabis allergies and their symptoms

It is important to differentiate between legitimate cannabis allergy symptoms and allergic reactions to substances in cannabis that are not inherent to the plant, such as moulds. In other words, cannabis can become mouldy when stored and people with mould allergies can have reactions. Some people may even have reactions to both the plant and the mould. It’s a bit confusing, but we have evidence. Fungal contamination in marijuana samples has been shown to occasionally put patients with compromised immune systems at risk. A case of allergic bronchopulmonary aspergillosis attributed to fungal contamination of a patient’s marijuana supply has even been described. That’s not very encouraging, is it? It took steroid treatment to remedy the situation.

A true allergy to cannabis is a reaction to a specific substance contained in the cannabis plant. In “Cannabis Sativa: the unconventional ‘weed’ allergen“, Ocampo and Rans provide an excellent review of the existing literature on the subject. They describe how reports in the medical literature have described episodes of allergic reactions, hypersensitivity and even anaphylaxis to cannabis in its various forms.

Inhalation of cannabis pollen has caused symptoms of allergic rhinitis, conjunctivitis and asthma. Exposure to pollen or smoke has resulted in nasal congestion, rhinitis, sneezing, conjunctival infection, pharyngeal pruritus (itchy throat), coughing, wheezing and dyspnoea (difficulty in breathing). Skin irritations thought to be associated with cannabis use have been described. Skin contact when handling plants has been associated with urticaria, generalised pruritus and angioedema (swelling). Anaphylaxis (severe reaction) associated with eye symptoms, urticaria, angioedema, dyspnoea (difficulty breathing) and dysphonia (difficulty speaking) has been reported following ingestion of cannabis seeds. Cases of allergic asthma triggered by seasonal and occupational exposure to cannabis have also been reported.

Cannabis use was even considered a contributing factor in a case of eosinophilic pneumonia whose symptoms appeared after recreational exposure to marijuana.

Symptoms of sensitisation to cannabis

As with other airborne substances that can trigger allergic reactions (e.g. pollen!), sensitisation to cannabis can be influenced by aerobiology. People who live in areas where large amounts of marijuana plants are grown may be particularly prone to allergic reactions to pollen.

Rhinoconjunctivitis (nose and eye problems) is characterised by one or more of the following symptoms:

  • Red eyes
  • Nasal congestion
  • Runny nose
  • Sneezing
  • post-nasal drip
  • Itching of the nose or eyes


Although still relatively uncommon, cannabis allergies are being reported with increased frequency. Allergic reactions as severe as anaphylaxis attributed to cannabis have been noted with sensitization associated with pollinosis, cannabis consumption, occupational exposure, and potential plant cross-reactivity. However, there is no reason to panic. It’s to be expected that the reporting of cannabis allergies would increase as cannabis consumption became more mainstream.

Cannabis allergies can be treated in much the same way as other allergies (mostly with antihistamines) but the lack of standardization in testing limits validation and the widespread applicability of diagnostic testing.

Cannabis allergies - grower

Find out if you are suffering from cannabis allergies at home. Take a cannabis flower and run it over the bare skin on the top of your hand several times. If hives appear within minutes, it’s likely you have some form of cannabis allergy. This way, most growers find out very quickly that they are sensitive to cannabis during the harvest.

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Published by Sakul


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