Can You Be Allergic to Weed?

You can be allergic to weed, although a true allergy to cannabis (marijuana) is thought to be rare. Some studies suggest the rate of a weed allergy may be as low as 1%, with people reporting symptoms ranging from skin rash and nasal congestion to severe diarrhea and asthma. Rare cases of a potentially fatal allergy, called anaphylaxis, have also been reported.

Rates of cannabis allergy are thought to be increasing due to the increased legalization of marijuana in the United States and around the world.

This article explains the symptoms of a weed allergy by whether you eat it, touch it, or smoke it. It also explains why cannabis allergies occur and how they are diagnosed and treated.

Signs of a Weed Allergy

Symptoms of a cannabis allergy are similar to symptoms of other allergies but can differ depending on the mode of exposure. Most allergy symptoms develop fast, usually within 30 minutes. Other people have a delayed reaction and may only notice symptoms hours or days later.

The timing of symptoms is largely influenced by whether you smoke, eat, or touch cannabis.

Skin Exposure

A marijuana allergy can cause a skin reaction when a person touches or handles the plant or its flowers. Symptoms of contact allergy include:

• Itching
• Redness
• Rash
• Hives (urticaria)
• Dry, scaly skin

A person with a weed allergy can also get symptoms after using topical creams and oils containing cannabidiol (CBD).

Smoking

Smoking marijuana is the most common use of recreational or medical cannabis. Firsthand or secondhand exposure to cannabis smoke may cause respiratory symptoms like asthma or allergic rhinitis (hay fever). Other people may have systemic (whole-body) reactions affecting the skin and other organs.

Allergy symptoms associated with smoking cannabis include:

• Nasal congestion
• Sore throat
• Shortness of breath
• Chest tightness
• Wheezing
• Dry coughing
• Generalized itching with or without rash or hives
• Swollen, watery eyes

Cleaning or handling cannabis can also expose you to cannabis pollen you can inhale. In some cases, mold on improperly stored cannabis can trigger allergy symptoms when inhaled.

Consumption

As the legalization and use of medical marijuana have become more widespread across the United States, so has the popularity of cannabis-infused edibles. Allergic reactions are often more pronounced because larger amounts of cannabis are introduced into the body where they can remain until the plant is fully digested.

Allergic symptoms of oral cannabis exposure may include:

• Swollen, teary eyes
• Generalized itching
• Rash or hives
• Angioedema (generalized swelling of tissues)
• Stomach ache
• Diarrhea

Why Am I Allergic to Weed?

As with all "true" allergies, cannabis allergies involve an abnormal immune reaction to an allergy-causing substance (known as an allergen). Exposure to the allergen triggers a specific immune response characterized by the release of an antibody called immunoglobulin E (IgE).

The release of IgE sets off a chain reaction in cells that spurs the release of another chemical called histamine. This is the substance responsible for allergy symptoms in the skin, eyes, respiratory tract, digestive tract, and circulatory system. The IgE response can result from inhaling, smoking, touching, or eating cannabis allergens.

The four substances in cannabis identified as allergens are called:

• Profilin
• Nonspecific lipid transfer protein
• Oxygen-evolving enhancer protein
• Pathogenesis related protein
  

Cross-Reactive Food Allergy

There is a known cross-reactivity between certain foods and cannabis. If you're allergic to one of the following, you may also develop a reaction to marijuana (and vice versa):

• Almonds
• Apples
• Bananas
• Chestnuts
• Eggplant
• Grapefruit
• Peaches
• Tomatoes

The reaction occurs because cannabis and these foods share similar allergenic proteins. Depending on which is the true allergy—the cannabis or the food—symptoms can range from mild (such as lip swelling and mouth itching) to severe.

Diagnosing a Weed Allergy

In most cases, your provider can diagnose cannabis allergy based on your symptoms. If needed, they may refer you to an allergist to undergo allergy testing.

There are no specific tests for cannabis allergy. Because of this, the allergist may prepare a cannabis extract from the leaves, buds, and flowers to use for skin testing.

There are two forms of skin tests used to diagnose allergies:

• Patch testing in which the allergen is applied to an adhesive patch and placed on your skin
• Skin prick testing in which the allergen is introduced under the skin with a tiny needle

With patch testing, a reaction may appear within 48 hours or less if you have an allergy. With a skin prick test, the reaction may occur in as short as 15 minutes.

In addition to skin testing, there is a blood test called a RAST test that can help diagnose allergies based on IgE levels in your blood. After blood is drawn, the allergen is introduced into the sample to see if it triggers an IgE response.

Treatment for Weed Allergy

If you think that you have developed an allergy to marijuana, the best thing to do is avoid it. This means no longer smoking weed or consuming edibles, as well as refraining from touching it and having any secondhand exposure to it.

If you are using marijuana for medicinal purposes, this may be difficult. Talk to your provider. They might suggest alternative treatment options for your condition.

If you have had a severe reaction to marijuana, you might need to carry an epinephrine auto-injector (Epi-pen) at all times. This medication acts quickly to treat severe allergy symptoms, such as trouble breathing and a drop in heart rate. Some people need to carry more than one Epi-pen just to be safe.

When You Can't Avoid Exposure

Sometimes, avoiding airborne exposure to marijuana is challenging. This is often true for people who work in the cannabis industry or live with someone who smokes pot.

In these cases, you can try:

• Taking antihistamines or decongestants to treat symptoms like runny nose and red eyes
• Using an air purifier or opening a window if someone is smoking cannabis
• Wearing gloves or a face mask when handling cannabis or in the company of a sm

Summary

It’s possible to be allergic to weed, but researchers don’t know how common it is. If you're allergic to marijuana, you may get symptoms such as itching, redness, hives, or a runny nose. The symptoms might be different depending on whether you touch, eat, or breathe in smoke, dust, or pollen from the marijuana plant.

If you think you're allergic to weed, avoiding it will help prevent symptoms. If you use marijuana for medicinal purposes or can’t avoid it because you live with someone who uses it or you work around it, talk to your provider about steps you can take to manage your allergy.