Cannabis Science

What Happens If You Smoke Moldy Weed?

moldy weed nug in hand

Maybe the weed you’ve been saving for the perfect day smells moldy. Or you bought weed from a dispensary and suspect something is slightly off. We get it. it’s annoying to toss your weed and inconvenient to return to the dispensary. However, using moldy weed may not be the greatest idea. Here’s what happens if you smoke moldy weed. 

Photo: Unsplash

What Do I Do If I Have Moldy Weed?

First of all, you need to make sure that you have moldy weed and that you’re not mistaking mold for trichomes. The main telltale sign is the smell. Moldy weed may smell like mildew or hay. Another way to tell is by looking out for a powdery greyish-white substance. Trichomes are more glittery in appearance and look like little hairs. 

Once you’ve confirmed that you have moldy weed, toss it! That’s right, don’t put it in your bong, blunt, edible, or anything else except the bin. 

If you don’t believe us, maybe you’ll believe a doctor. 

According to Board-certified Pediatrician Dr. David Berger, founder and medical director of Wholistic ReLeaf, a division of Wholistic Pediatrics & Family Care, and DrDavidMD, a health education company, don’t use moldy weed.

Berger told us, “If it was recently purchased at a store, or especially a medical dispensary, ask for a refund or replacement product.”

How Do I Prevent My Weed From Getting Moldy?

Nobody wants to waste money on weed they can’t use or not have their stash available when they need it. Therefore, more effort needs to be made in preventing your weed from getting moldy. 

Berger says, “It is important to know how to prevent cannabis from getting moldy. To do this, cannabis needs to be kept in a dry environment. To keep humidity at an appropriate level, products such as containers and humidity packets can be helpful.”

What Happens If I Smoke Moldy Weed?

You’re probably curious about what will happen if you smoked moldy weed. You may be surprised to know that mold is not the only concern when using moldy weed.

However, let’s look at the problem with mold first. If you’re immunocompromised, you may be at a greater risk of medical issues than someone who is otherwise healthy. 

Winston Peki, cannabis expert and founder of, “Most fungal species can be especially dangerous to people with compromised immune systems.”

However, people with normal immune systems, have less to worry about. Berger told us, “As mold cells are killed at high temperatures, it would be very unlikely to get a mold infection in the lungs. Furthermore, mold is unlikely to take hold and cause infection in people with healthy immune systems.”

However, that does not make smoking moldy weed safe. The problem lies in the mycotoxins according to Berger. 

Berger tells us that mycotoxins, chemicals created by mold, aren’t destroyed by smoking. As a matter of fact, he explains to us that mycotoxins are transferred into the smoke and deposited into the respiratory tract. 

There are a number of side effects you could face.

Berger explains, “Often, side effects are more unpleasant than dangerous by irritating the airway and causing a cough. It also may alter the taste or even cause nausea or vomiting.”

On the other hand, people with mold allergies, which may also be allergic to mycotoxins may have more severe side effects. Berger tells us that those persons may have upper respiratory issues such as congestion or sinus inflammation and lung inflammation such as asthma.

Can I Vape Moldy Weed?

Unfortunately, your vape oils aren’t safe either. Mycotoxins can be present and cause issues.

However, good quality products from reputable places should test for mycotoxins and have the information readily available on their website.

Before you purchase, Berger told us, “Better quality products should have each batch tested for mycotoxins. This is part of a Certificate of Analysis, which also should test for other toxins like heavy metals and pesticides.”

He continued, “High-quality products should have this readily available on their website; some even have QR codes that go to the website to be viewed. I would not buy a product that did not have this level of transparency.”

Berger also mentioned that while the marijuana plant products may be tested beforehand, the results are only indicative of their mycotoxin status at the time of testing. Mold can grow afterward. 


What happens if you smoke moldy weed?  For most people, mold won’t cause fungal infection, especially since it’s destroyed by smoking. However, immunocompromised people, may not be so lucky. Regardless of the state of your immune system, you may experience a cough, nausea, vomiting, or notice a difference in the taste of the weed. However, if you’re allergic to mold or mycotoxins then you could have more severe symptoms such as asthma. Whether you’re considered healthy or not, it’s not worth it to smoke moldy weed. Just toss it, get a fresh batch, and store this batch properly.


About Trevann

Trevann is Stoner Rotation’s Jamaica-based lead writer for the Science section of our cannabis blog. She graduated with honors receiving her Bachelor of Science degree in Molecular Biology from the University of West Indies, Mona. For the last three years, she has covered some of the biggest questions around cannabis and health underpinned with research from supporting studies, medical journals and scholarly articles. Got something on your mind? You can reach her at [email protected].