What Are the Symptoms of Marijuana Allergy and How to Treat It?

Marijuana allergy is real, rare and affects 1 out of every 100 users. Are you one of them?

Look, the chances are slim that you are, but marijuana allergy does exist.

It’s just the truth:

There are people who could smoke 5 grams a day for decades and not even flinch (and they are the majority) and then there are those unlucky few who develop an allergic reaction to cannabis and end up giving up smoking altogether.

I mean, how many Kleenex can you buy before you say it’s enough?

Any contact with the plant can trigger an allergic reaction:

  • Smoking dried flowers
  • Ingesting CBD oil
  • Eating edibles
  • Exposure to the plant’s pollen

Every time an allergic person consumes marijuana in any way, shape or form, they are subjected to a different variety of symptoms, which can range from mild to potentially serious if left untreated.

Here’s how marijuana triggers allergic reactions

Marijuana allergy has been investigated in several clinical studies, and two studies have been published recently.

The first one, published in 2013, set about to identify Cannabis Sativa allergens by testing a group of people through skin prick testing. (1)

In their study, researchers found 17 cannabis users who tested positive for an allergic reaction to cannabis. All patients showed similar symptoms (which you can find below) but, most importantly, this study identified what exactly causes people to be allergic to weed.

The big answer:

Peptides from enzymes connected to the plant’s primary metabolism.

For all of you chemistry geeks out there, these are RuBisCO, oxygen evolving-enhancer protein, ATP synthase, phosphoglycerate kinase, and glyceraldehyde-3-phosphate dehydrogenase.

The second study was published in 2015 — this one categorized cannabis allergy as something like fruit and vegetable allergy, therefore placing it in the “cannabis-fruit/vegetable syndrome”. (2)

Some would say that this is minor, and that pineapple has never killed anyone. But there’s a twist…

This 2015 study explored various possibilities of cross-allergic reactions with tobacco, natural latex and plant-derived alcoholic beverages. Which is pretty good to know, having in mind that weed is often smoked with tobacco, in blunts for example.

If we get rid of the scientific jargon, we can see that these two studies helped us understand something very important:

Marijuana allergy is very rare but when it does occur it has similar symptoms as some common food and plant allergies.

We got the plant’s role down, now we need to address another allergen that can be found in low-quality buds:


Mold can be commonly seen on weed that hasn’t been stored and cured properly.

Moldy weed

If you remember our weed expiration date article, moldy weed can be toxic and unsmokable, and can even cause respiratory issues in some cases.

Besides being weed’s number one enemy, the mold is also an enemy of the humans (it’s basically Batman vs Joker at this point).

When you smoke moldy weed you also inhale mold spores, which can cause symptoms such as itching, runny nose, nasal congestion.

Long-term smokers can develop an intolerance also

Marijuana allergy is not limited to first time users. It can happen with long-term users as well.

Just so you know.

There is a condition called Cannabinoid Hyperemesis Syndrome (CHS) — if you’ve been smoking marijuana for a long time you’ve probably heard about it.

According to this 2011 publication by the Temple University Hospital, CHS is characterized by chronic cannabis use, cyclic episodes of nausea, vomiting and bathing with hot water (which is a learned reaction apparently). (3)

It develops all of a sudden and ONLY in long-term regular smokers. And it sucks.

I came across an NY Mag interview of a woman that found out she has CHS. She had terrible nausea and vomiting sessions and finally, after a dozen tests, her doctor told her that she developed an intolerance to cannabis.

In the end, she had to quit smoking. Yikes.

The most common marijuana allergy symptoms

All cannabis allergy symptoms usually occur 20-30 minutes after exposure to the plant.

And by that, I mean any kind of contact — it doesn’t matter if you smoke it, eat it, inhale pollen or even touch the plant.

But how do you know if you’re having an allergic reaction to weed?

Pretty simple, if you experience one of the following the next time you use weed, then you’re probably allergic.

Here are the most common marijuana allergy symptoms:

● Sore throat
● Nasal congestion
● Rhinitis
● Watery eyes
● Post-nasal drip
● Inflammation of the throat
● Difficulty breathing
● Swelling below the surface of the skin
● Vomiting
● Gastric cramping
● Itching
● Rashes

Take note that that the intensity of these symptoms can vary, depending on the amount of cannabis you consumed.

For example:

An allergic person who smoked 4 joints can experience more itching than a person who smoked 1 joint.

Even though marijuana allergy usually presents itself with mild symptoms, such as a runny nose and watery eyes, there are some unlucky people who get the short end of the stick and get a potentially deadly reaction called anaphylaxis.

Anaphylaxis from smoking weed does happen:

A couple of minutes after ingesting marijuana, an allergic person experiences reaction not just in one spot, but throughout their entire body, setting off a chain of physiological processes that send him into a state of shock.

Anaphylactic shock is life threatening and should be treated ASAP with a shot of adrenaline (Epinephrine).

Learn the signs of anaphylactic shock

Every person should learn to recognize the symptoms of anaphylaxis, smoker or not.

It can happen with just about any allergen and it is an extremely dangerous reaction that

requires immediate medical attention. If you know to recognize it, you can get help much quicker and that can save your life.

According to EpiPen, these are signs and symptoms of anaphylaxis:

  • Skin reactions (generalized hives, itching, swelling, reddening)
  • Respiratory problems, swollen throat and tongue
  • Reduced blood pressure, dizziness and fainting
  • Vomiting, abdominal & GI cramping

If someone has these symptoms, call an ambulance right away, because that person needs urgent help.

Thankfully, anaphylaxis can be resolved in a couple of minutes with a shot of adrenaline — it complements your body’s own adrenaline to reduce throat swelling, open up breathing pathways and regulate blood pressure.

How to treat marijuana allergy

So, after all of this, you’re pretty sure that you are allergic to weed?

OK, first, book an appointment with your doctor. An allergist would be the best bet.

They’ll do a skin test and prescribe a therapy, tailored to your symptoms. The therapy can involve either medication or completely avoiding any contact with marijuana.

If your allergic reaction to weed is severe, then you need to quit smoking altogether.

However, since I know that most of us like to delay a trip to the doctors as much as possible, you can always use a nasal spray and some antihistamines for treating the acute onset of mild marijuana allergy symptoms.

As things are currently, there is only a small number of reported cases of marijuana induced allergies.

But as weed becomes more and more accepted, you can bet that we’ll start seeing more people complaining about allergic reactions to the plant.

Those people will be growers, people who live next to cannabis fields or regular users. The good news is:

Marijuana is, in the end, a very mild allergen and can be safely consumed by 99% of users.

Unfortunately, there will always be an unlucky few.


  1. Nayak AP, Green BJ, Sussman G, Berlin N, Lata H, Chandra S, ElSohly MA, Hettick JM, Beezhold DH; Characterization of Cannabis sativa allergens; Annals of Allergy, Asthma and Immunology; July 2013; 111(1):32-37
  2. Decuyper I, Ryckebosch H, Van Gasse AL, Sabato V, Faber M, Bridts CH, Ebo DG; Cannabis Allergy: What do We Know Anno 2015;  Archivum Immunologiae et Therapia Experimentalis; October 2015; 63(5):327-332
  3. Galli JA, Sawaya RA, Friedenberg FK; Cannabinoid hyperemesis syndrome; Curren Drug Abuse Reviews; December 2011; 4(4):241-9
About the author
Luka Petkovic

Editor in chief at Greencamp. Researching topics related to the biochemistry of cannabinoids and interested in the latest industry happenings.

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