Cannabis Allergies & Hypersensitivity Guide

"Can you be allergic to weed?" is a question you may be asking yourself if you've experienced an unexpected reaction after consuming MMJ. The short answer is yes, you can be allergic to cannabis. Allergic reactions and hypersensitivities to cannabis range from mild to severe. The symptoms are often similar to those of hay fever. Severe cannabis allergies are rare.

It’s essential to see an experienced medical marijuana doctor or an allergy specialist if you suspect a sensitivity to cannabis. Correct diagnosis and a professional treatment plan will help you prevent the problem from becoming worse.

Important: The information in this article is intended to be educational in nature. It does not substitute for professional diagnosis, treatment, or recommendations, and does not create a doctor-patient relationship. Talk to a licensed medical professional if you suspect a sensitivity to cannabis and call your emergency medical number right away if you are experiencing a medical emergency or are having trouble breathing.

What Causes Cannabis Allergies?

A cannabis allergy, like other common allergies, occurs when the immune system mistakenly identifies components of the cannabis plant as harmful. This triggers an allergic reaction. While not as common as other allergies, it can significantly impact those affected.

Risk Factors for Cannabis Allergies

Risk factors for cannabis allergy include the following. Mention them to your MMJ doctor when you go to apply for or renew your medical marijuana card.

1. Sensitivity to Allergens in the Cannabis Plant

The cannabis plant contains several proteins and other substances that trigger allergic reactions in some individuals. These include:

• Can s 3 (Lipid Transfer Protein / LTP): Can s 3 is the main recognized cannabis allergen. It’s the primary contributor to systemic and cross-reactive allergic responses. In rare cases, it can cross-react with related plant allergens, including those found in certain fruits, vegetables, and other plant foods. 

• Can s 2 (Profilin): Profilin is another recognized cannabis allergen. Profilins are common plant proteins. They could contribute to localized respiratory or contact reactions. Allergic reactions could also be caused by cross-sensitization with other plants and pollens.

• RuBisCO: RuBisCO is a plant protein that has been identified as a potential cannabis allergen. It may contribute to localized respiratory or contact symptoms. 

• Pollen: Airborne cannabis pollen can trigger allergic reactions similar to other plant pollen allergies. Pollen is only produced by the male cannabis plant (and the flowers customers buy are female), so exposure to cannabis pollen is more likely near outdoor cultivation sites or industrial hemp fields.

• Plant matter: Direct contact with the cannabis plant, such as handling the leaves or flowers, can cause skin reactions.  

• Cannabis smoke: Inhaling cannabis smoke may irritate the respiratory system. This could be caused by an allergic reaction (involving IgE antibodies) or simply represent smoke-related airway irritation from combustion byproducts, particulate matter, or heat. Coughing or wheezing after smoking cannabis does not by itself establish an allergy to the plant.

• Cannabis-derived products: Ingesting cannabis-infused edibles or topicals can cause allergic reactions in some individuals.

• Cannabinoids and terpenes: While less common, cannabinoids and terpenes may also trigger mild allergic reactions such as contact dermatitis in some people. However, the evidence is much more limited than it is for allergies to cannabis plant proteins.

2. Having Certain Food Allergies

Cross-reactivity occasionally occurs between cannabis and other plant-based allergens because some foods contain proteins that are structurally similar to cannabis allergens. The best-established connection involves Can s 3, the lipid transfer protein found in the cannabis plant.

Common foods with allergy properties similar to those in the cannabis plant include:

• Tomatoes

• Avocados

• Fruits like peaches, grapefruit, apples, bananas, and citrus fruits

• Soy

• Almonds, hazelnuts, and walnuts 

(See the section titled: “Links Between Cannabis Allergy and Food Allergy”)

How Cross-Reactivity Happens

Proteins in foods that cross-react with cannabis closely resemble Can s 3. This triggers the immune system in people who are sensitized to this allergen. In a sensitized person, IgE antibodies directed against one lipid transfer protein can recognize a similar LTP in another source, producing an allergic response.

This cross-reactivity is referred to as cannabis-fruit/vegetable syndrome. Oral symptoms may include itching, tingling, or swelling of the lips, mouth, or throat after consuming these foods, particularly when cannabis exposure is also involved. As lipid transfer proteins are heat- and digestive-resistant, systemic reactions such as hives or anaphylaxis could also occur.

3. Allergic Sensitization

Allergic sensitization refers to the process that results in a person's body becoming sensitive to any given allergen. Sensitization that leads to allergy symptoms can occur from ingestion, inhalation, or direct skin contact. Repeated occupational exposure to cannabis may increase opportunities for sensitization. Sensitization may also be more likely in areas where cannabis plants are grown. 

Speak to a doctor if you think you may be developing signs of a cannabis allergy. Doctors in states where medical cannabis is legal, like Arizona, may be familiar with the signs of a cannabis allergy and refer you to a specialist.

The Spectrum and Severity of Cannabis Allergy Symptoms

Cannabis allergy symptoms range from mild skin irritation to potentially serious respiratory or systemic reactions. The type and severity of symptoms often depend on how the person was exposed.

Cutaneous (Contact) Symptoms

Handling raw cannabis, trim, or unrefined topicals can cause itching, hives (urticaria), flushing, redness, or contact dermatitis. Angioedema (deeper swelling) can also occur.

Respiratory (Inhalation) Symptoms

Inhaling cannabis allergens through smoking, vaping, or exposure to airborne pollen may trigger allergic rhinitis, sneezing, nasal congestion, itchy or watery eyes, wheezing, throat tightness, or asthma exacerbation. 

Remember that wheezing and other forms of respiratory irritation after smoking may be from the combustion byproducts, smoke, or heat, and not represent an allergic reaction to cannabis.

Systemic / Severe Reactions

Anaphylaxis caused by exposure to cannabis is rare but has been documented. Severe reactions potentially cause hives, significant swelling, difficulty breathing, vomiting, dizziness, or loss of consciousness and require emergency medical attention.

Can Handling the Cannabis Plant Cause Allergic Reactions?

Yes, handling the cannabis plant can cause allergic reactions that resemble dermatitis. This risk significantly rises if you handle cannabis regularly. Individuals who grow their own cannabis or work in the cannabis industry should wear appropriate personal protective equipment (PPE).

Cannabis Allergy vs Contaminant Sensitivities vs CHS

Not every reaction after using cannabis is a true cannabis allergy. Symptoms such as coughing, sinus irritation, skin reactions, or severe vomiting can have very different causes. These include an IgE-mediated cannabis allergy, cannabinoid hyperemesis syndrome (CHS), or sensitivity to contaminants such as mold or residual chemicals. 

Understanding these distinctions helps patients identify what may be triggering their symptoms and when medical evaluation is appropriate.

True IgE-Mediated Cannabis Allergy

A true cannabis allergy occurs when the immune system produces an IgE-mediated response to cannabis allergens. Possible symptoms include hives, itching, sneezing, nasal congestion, conjunctivitis, swelling, wheezing, bronchospasm, or, in the most serious cases, anaphylaxis. Cannabis allergies occur after inhalation, skin contact, or ingestion.

Cannabinoid Hyperemesis Syndrome (CHS)

Cannabinoid hyperemesis syndrome (CHS) is not an allergic reaction. It's a condition associated with prolonged, frequent, and heavy cannabis use. Common symptoms include severe nausea, vomiting, and abdominal pain. Affected individuals often report temporary relief from symptoms with hot showers or baths. However, recurrent vomiting associated with cannabis use warrants medical evaluation, diagnosis, and treatment.

Mold, Pesticide, and Other Contaminant Sensitivities

Respiratory irritation, coughing, sinus symptoms, or other reactions after consuming cannabis may sometimes be related to contaminants rather than cannabis itself. Poor-quality cannabis purchased outside licensed dispensaries sometimes contains microbiological contaminants. Exposure to fungal material is particularly concerning for people with respiratory conditions or weakened immune systems. 

Regulated cannabis products in Arizona undergo laboratory testing for a range of contaminants. These include microbial contaminants, heavy metals, pesticides, fungicides, growth regulators, and residual solvents. Some certified labs also have the capabilities to test for E. coli, Salmonella, Aspergillus, and mycotoxins. Buying regulated products can reduce exposure to the contaminants covered by Arizona testing requirements.

Cannabis Contact Allergy vs Inhalation Allergy vs CHS vs Mold Exposure

The following table outlines the main differences between common causes of unexpected symptoms after consuming cannabis:

Feature	Contact Allergy	Inhalation Allergy	CHS	Mold Exposure
Primary cause	Skin contact with cannabis or topical ingredients	Inhaling cannabis pollen, plant particles, or cannabis smoke	Chronic cannabis use that triggers a gastrointestinal syndrome	Exposure to mold or fungal contaminants on cannabis
Typical symptoms	Itching, redness, rash, hives, or swelling where exposed	Sneezing, runny/stuffy nose, itchy eyes, coughing, wheezing, or breathing difficulty	Recurrent nausea, vomiting, abdominal pain, and often compulsive hot bathing for relief	Coughing, wheezing, congestion, sinus irritation, or allergy-like symptoms
Where symptoms occur	Mainly on the skin	Primarily the nose, eyes, throat, and lungs	Primarily the gastrointestinal system	Primarily the respiratory system
Timing	Usually after skin exposure	Often shortly after inhalation	Typically develops after repeated or long-term cannabis use	Can occur after exposure to contaminated material
Typical trigger	Cannabis plant material or topical products	Smoke, pollen, or airborne plant proteins	Cannabis use itself, particularly frequent use	Mold-contaminated cannabis or environmental mold
How it's evaluated	Medical history, examination, and sometimes patch testing	Allergy testing, respiratory evaluation, and medical history	Clinical history and symptom pattern; improvement after stopping cannabis supports the diagnosis	Exposure history, clinical evaluation, and sometimes allergy or respiratory testing
Key distinction	An allergic skin reaction	An allergic respiratory reaction	Not an allergy; a cannabis-associated gastrointestinal syndrome	May represent an allergic or irritant response to mold

How Is a Weed Allergy Diagnosed?

Weed allergies are typically diagnosed based on clinical history, skin prick tests, and patch testing. There is no universally standardized commercial diagnostic test.

Skin Tests for Weed Allergies

Doctors may use a skin prick test to determine whether you have a cannabis allergy. This is a minimally invasive test that yields quick results. During a skin prick test, the doctor will apply a diluted version of the allergen (such as a nonstandardized cannabis extract) to the pricked surface of the skin. If the skin reacts within 15 minutes, you’re likely sensitive to cannabis.

Patch Testing for Topicals

Patch testing for cannabis topicals involves placing small amounts of suspected allergens on the skin under adhesive patches for a set period. The skin is then checked for redness, swelling, itching, or other reactions to identify potential contact allergens. This method may be appropriate if allergic contact dermatitis is suspected.

How to Manage Cannabis Allergies

The best way to prevent a weed allergy from developing is to avoid excessive direct exposure to the plant. You might need to avoid cannabis altogether if you've suffered an allergic reaction. Patients with previous severe systemic reactions may need epinephrine prescribed by an allergist. The following strategies could be helpful if you are not sure whether you’re sensitive to cannabis:

• Consult a doctor: Consult with an allergist for proper diagnosis and treatment if you suspect a cannabis allergy. A specialist may be able to recommend an effective marijuana allergy treatment regimen that reduces its impact.

• Identify the source of the problem: Try to work out the exact conditions that trigger your symptoms. For example, you may be experiencing nonallergic respiratory irritation from smoke but would be fine with cannabis edibles.

• Avoid direct contact: Wear gloves and protective clothing when handling cannabis plants or products. This is especially important if you have regular contact with cannabis at home or work.

• Proper ventilation: Ensure good ventilation when handling or consuming cannabis products indoors.

• Air filtration: Use air purifiers with HEPA filters to reduce airborne allergens.

• Allergy medications: Over-the-counter antihistamines or other allergy medications may help manage mild allergy symptoms if you can’t avoid contact with cannabis completely. Patients with a history of severe systemic reactions should receive individualized emergency advice.

Remember: A true cannabis allergy is rare. Most medical patients consume cannabis regularly without experiencing the symptoms described in this article.

Watch Out for Cannabis Allergy Symptoms 

Cannabis allergies, while less common than many other allergies, cause unwelcome and even severe symptoms. Affected individuals will need to manage their allergies by understanding the symptoms and triggers and developing prevention strategies with a medical professional. If it’s your first time smoking cannabis, it’s a sensible precaution to have someone with you in case you experience any unexpected effects.

It's crucial to seek medical advice for proper diagnosis and treatment if you suspect a cannabis allergy. A healthcare professional will work with you to develop a personalized management plan.