Using cannabis for allergies is something some consumers describe trying during allergy season, but the research on cannabinoids and allergic inflammation is early and mixed, and it falls short of showing that cannabis relieves hay fever or any other allergy.
So why do some people reach for a joint when pollen counts climb, while others start sneezing as soon as they open a jar?
In this guide, you’ll discover:
- what an allergic reaction involves, from IgE antibodies to histamine;
- what peer-reviewed research says about cannabinoids and allergy;
- how smoking, vaping and edibles fit into allergy season;
- why some people are allergic to cannabis itself, and how that allergy is diagnosed.
This guide is general information, not medical advice. Talk to a health care practitioner about your own situation.
Can cannabis help with allergies?
The evidence is thin. Health Canada’s consumer information states that the evidence for the safety and efficacy of cannabis for medical purposes is limited or unknown, and allergy relief sits inside that gap. What circulates online is mostly anecdotal: users report less congestion, fewer sneezing fits or less itchy eyes in pollen season, which says little about whether the cannabis, the setting or the weather made the difference. The same gap between anecdote and data runs through other health questions, such as whether cannabis lowers blood pressure.
Researchers still take the question seriously, because the body’s own cannabinoid signalling is part of how the immune system behaves. In Canada, under the Cannabis Act (in force since October 17, 2018), patients authorized by their health care provider are still able to access cannabis for medical purposes from a federally licensed seller, a framework explained in our guide to Health Canada licensed producers. Any question about allergy symptoms, cannabis included, belongs in a conversation with a doctor or another practitioner.
What happens in an allergic reaction
Health Canada describes an allergy as the immune system treating a harmless protein, the allergen, as a threat. On first exposure, the immune system creates antibodies called immunoglobulin E (IgE). On the next exposure, IgE antibodies and chemicals such as histamine are released, and histamine can set off reactions in the respiratory system, the skin, the gut or the cardiovascular system.
For airborne allergies, Health Canada names allergens such as house dust mites and mould, and lists sneezing, coughing, wheezing, shortness of breath and red, itchy, swollen eyes among the usual allergy symptoms. Immediate reactions show up as hay fever (allergic rhinitis) or allergic asthma, and people who develop one allergy are more likely to develop others. That point matters when the allergen is cannabis itself.
Cannabinoids and allergy: what research suggests
The link researchers study is the endocannabinoid system (ECS): the cannabinoid receptors, signalling molecules and enzymes the body produces on its own. A 2020 review in International Archives of Allergy and Immunology notes that alterations in the ECS are associated with immune-mediated disorders such as allergy. It also finds that cannabinoids, a family that includes the phytocannabinoids of the cannabis plant such as THC and CBD, play a role in allergic responses, although their actual contribution is still controversial.
Anti-inflammatory findings in allergic patients
Some studies covered by that review found that cannabinoids exert anti-inflammatory properties in the airways and the skin of allergic patients. That finding is the one most often stretched into allergy-relief marketing. Read closely, it describes a mechanism under study, a long way from a jar of flower that eases hay fever.
Cannabinoids and worsening asthma
The same review reports other studies where cannabinoids might exacerbate asthma and atopic dermatitis, mainly through signalling at the CB2 receptor. The research therefore points in both directions, and the authors call for a better understanding of specific cannabinoids and cannabinoid receptors as a step toward future prevention and treatment strategies. For a reader with seasonal allergies, the fair summary is promising, unproven and possibly counterproductive.
Cannabis formats during allergy season
How cannabis is consumed (smoking, vaping, edibles or topicals) matters more in pollen season, when eyes, nose, sinuses and airways may already be irritated by allergens.
Smoking and vaping with hay fever
Health Canada warns that the toxic chemicals in cannabis smoke increase the risk of heart and lung disease, and that cannabis vapour may also carry risks. For someone already coughing or wheezing through hay fever, smoke is one more irritant for the airways to handle. Inhalation is also a recognized route of sensitization to cannabis, and asthma is among the conditions the 2020 review says cannabinoids might worsen.
Edibles, oils and hemp seed
Edibles, tinctures and cannabis oils avoid smoke entirely, which is why some consumers describe them as their allergy-season format. Ingestion carries its own allergy angle, though: peer-reviewed case reports describe anaphylaxis after eating hemp seed, which comes from the same species, Cannabis sativa. Topicals, for their part, involve skin contact, one of the exposure routes through which the 2020 Canadian review says sensitization to cannabis can occur.
Mixing cannabis and antihistamines
Health Canada notes that cannabis can interact with other drugs and substances, sometimes with serious side effects, and asks consumers to tell their health care practitioner about any prescription or non-prescription drugs they take or change. Over-the-counter antihistamines, decongestants and nasal sprays fall in that second group. Health Canada also advises caution when combining cannabis with other health products and asks consumers to avoid combining it with intoxicating substances such as alcohol.
Terpene profiles and allergy claims
Strain lists promoting weed for allergies usually lean on terpenes, the aromatic compounds behind a flower’s citrus, pine or fuel notes. A terpene profile is real information about aroma and flavour, and our sensory guide to terpene profiles explains how to read one by smell and taste. Neither of the peer-reviewed reviews cited on this page ranks terpenes, strains or cultivars for allergies.
A cultivar page such as Gelato 33 describes lineage and sensory notes so you know what you are choosing in the jar. Treat any allergy-relief promise attached to a strain name with caution.
Can you be allergic to cannabis?
Yes, and the evidence on this side is firmer. A 2020 review in Allergy, Asthma & Clinical Immunology, written in the context of legalization in Canada, describes cannabis allergy across the spectrum of hypersensitivity, from dermatitis to rhinoconjunctivitis to life-threatening anaphylaxis. Sensitization can occur through inhalation, skin contact, ingestion and secondhand exposure. Cannabis pollen has been implicated in allergic rhinitis, and handling plants is the route most relevant to growers, processors and other industrial workers. The best-studied allergen is Can s 3, a non-specific lipid transfer protein (nsLTP).
Because similar lipid transfer proteins exist in other plants, the authors describe a cannabis-fruit/vegetable syndrome, with cross-reactivity to cherry, tangerine, peach, tomato, hazelnut, latex and tobacco. Diagnosis rests on clinical history; the review adds that skin prick testing for cannabis is not standardized and that specific IgE blood tests for Can s 3 were not commercially available when it was published. The only proven treatment is avoidance, and anyone with anaphylactic allergies should carry auto-injectable epinephrine.
Cannabis and allergies: questions for your practitioner
A short list makes the appointment with your doctor or allergist more useful: your allergy symptoms and when they peak, every antihistamine, decongestant or other allergy medication you take, how often you smoke, vape or eat cannabis edibles, and whether a plant food, latex or a hemp product has ever caused an allergic reaction. Health Canada asks people who use cannabis for medical purposes to follow the dosing recommended by their health care practitioner and to monitor the treatment with them.
For adults who already enjoy cannabis, a legal product also means a known origin. LOT420 grows small-batch cultivars indoors in Mansonville, in Quebec’s Eastern Townships, and finishes each select batch by hand with an extended cure. The story behind that craft cultivation and the Health Canada licence and certifications are both published on our site.
FAQ: cannabis and allergies
Is cannabis an antihistamine?
Cannabis is not classed as an antihistamine. Antihistamines are allergy medicines that act on histamine, the chemical Health Canada describes as released along with IgE antibodies during an allergic reaction. Research on cannabinoids and allergy is early and mixed: a 2020 peer-reviewed review found anti-inflammatory effects in some studies and possible worsening of asthma and atopic dermatitis in others. Talk to a practitioner before combining cannabis with allergy medication.
Can smoking weed make allergies worse?
It can add to the problem. Health Canada warns that the toxic chemicals in cannabis smoke increase the risk of heart and lung disease, and that vapour may also carry risks. Peer-reviewed research adds that inhaling cannabis can sensitize some people to the plant and that cannabinoids might exacerbate asthma. In hay fever season, when coughing and wheezing are already common, smoke is one more irritant.
Does CBD help with seasonal allergies?
There is no reliable answer yet. CBD belongs to the cannabinoids that researchers study for their role in immune system and inflammatory responses, and a 2020 review describes that role in allergy as real but still controversial. Some consumers describe CBD products as part of their allergy-season routine, which remains anecdote. Health Canada considers the evidence for the medical use of cannabis limited or unknown.
What are the symptoms of a cannabis allergy?
A peer-reviewed review lists allergic rhinitis, inflamed, itchy eyes (keratoconjunctivitis), worsening asthma, generalized itching, contact urticaria (hives) and angioedema (deeper swelling), with life-threatening anaphylaxis at the severe end. Allergic reactions have followed smoking, eating hemp seed, handling cannabis plants and secondhand exposure. Anaphylaxis is a medical emergency, and an allergist can confirm what caused a milder reaction.
Which foods cross-react with a cannabis allergy?
The cross-reactivity comes from lipid transfer proteins that cannabis shares with other plants. A 2020 review in Allergy, Asthma & Clinical Immunology names cherry, tangerine, peach, tomato and hazelnut, along with latex and tobacco, in what it calls cannabis-fruit/vegetable syndrome. Someone who reacts to cannabis may react to these foods too, and the reverse link is worth raising with an allergist.
Can hemp seeds trigger a cannabis allergy?
Hemp seed comes from Cannabis sativa, the same species as THC-rich cannabis, and peer-reviewed case reports describe anaphylaxis after hemp seed ingestion. Ingestion is one of the routes through which sensitization to cannabis can occur. If you have reacted to cannabis or to hemp-based foods, check ingredient lists closely and ask an allergist whether testing makes sense for you.
How is a cannabis allergy diagnosed?
An allergist starts with your clinical history, which a 2020 peer-reviewed review calls the cornerstone of diagnosis: what you were exposed to, how, and what happened next. Skin prick testing can add information, but the review notes that cannabis skin tests are not standardized and that specific IgE blood tests for Can s 3 were not commercially available. The only proven treatment is avoidance, and anyone with anaphylactic reactions should carry epinephrine.
Can cannabis growers develop allergies to the plant?
Yes. Peer-reviewed research describes cannabis allergy in processors, agricultural workers and laboratory staff, and names the handling of plants as the route most relevant to industrial workers, the people who harvest, dry and cure resin-rich flower. Reported allergic reactions include contact urticaria (hives), allergic rhinitis and asthma symptoms. As the cannabis agricultural industry grows with legalization, the same authors note that the plant may also become a significant aeroallergen, which keeps occupational exposure on the allergy agenda.