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Dangers of Moldy Weed & How to Tell if Your Cannabis Is Bad

Consuming moldy weed is something that’s best avoided by everyone, but especially by medical marijuana patients with weakened immune systems. Knowing how to identify cannabis mold and also knowing how to prevent mold from forming on your buds is critical for keeping yourself healthy and your weed safe for consumption.


While we’ll go into more detail later on, the most important thing to know right out of the gate is that cannabis should be treated as you would treat food to keep it mold-free. Avoiding high temperatures, oxygen exposure, and moisture will help to keep your weed safe and in optimal conditions for consumption.

What Are the Dangers of Smoking Moldy Weed?

If you are generally healthy, moldy weed shouldn’t pose a huge risk to your health, although you may experience symptoms like coughing, wheezing, lung irritation, and nausea. However, for those with existing medical problems or allergies to mold, there could be serious health consequences if you smoke moldy weed.


After inhaling moldy cannabis, you may experience:

  • Sinus pain or congestion: Extreme cases can lead to a persistent sinus infection.

  • Fatigue/muscle weakness: Though smoking weed can often cause sleepiness, a more intense feeling of fatigue can indicate moldy cannabis.

  • Brain fog: High levels of THC in cannabis can lead to a feeling of fogginess, but this may be more intense or unpleasant after consuming moldy weed.

  • Persistent coughing: If coughing persists or is uncomfortable or painful after inhalation, this may indicate that your weed was contaminated with mold.

  • Chest pain: If your coughing causes chest pain or if you feel pain or pressure in your chest after consumption, you may have smoked moldy weed.

  • Fever: If you run a fever after smoking weed, see a doctor. Though it is rare, it's a concerning symptom that should be checked out by a professional.

How to Tell If Your Weed Is Moldy

There are some telltale signs of mold on your weed to look out for. Paying attention to the smell and appearance of your buds, in particular, can help you to avoid consuming moldy cannabis.

What Does Moldy Weed Smell Like?

Marijuana mold has a distinct odor that is unpleasant, musty, and/or mildew-like. Moldy weed can also smell dank and rotten, and consumers report a highly unpleasant and intense smell.

What Does Moldy Weed Look Like?

It can be tricky to identify moldy weed visually, as mold spores can be mistaken for cannabis trichomes—the shiny crystals on the leaves and buds of cannabis plants. These are two simple ways to tell the difference between mold and trichomes:

  • Mold on cannabis has a gray or white powdery appearance as opposed to the glittery, hairlike appearance of trichomes.

  • Mold can appear like webbing and will grow on the bud as opposed to trichomes that grow out from the cannabis plant.

How Can You Prevent Moldy Weed?

For consumers who grow their own weed, keeping mold at bay can be a complicated process. However, for patients who purchase their weed rather than grow it at home, there are certain steps you can take to keep your weed fresh and healthy after purchase.

1. Purchase Medical-Grade Marijuana From a Reputable Vendor

Medical-grade marijuana goes through stringent testing for pesticides, bacteria, and other contaminants before being sold. Cultivators are also subject to strict rules on the cultivation, processing, and storage of cannabis that’s intended for medicinal use.


Because certain types of mold, such as bud rot, originate in the growing phase, purchasing regulated cannabis should help to ensure a product that’s free from mold when you purchase it. Indeed, Jameson et al. (2022) reported that all states in which cannabis is legally approved for medicinal use must test for the presence of total yeasts and mold prior to sale since the presence of molds and other contaminants can negatively affect immunocompromised patients.

How to Gain Access to Medical-Grade Marijuana

Currently, 38 states, including Arizona, allow access to medical-grade marijuana with a doctor's certification and a valid medical marijuana card. Typically, you will need to renew your medical marijuana card every year or two to retain your patient privileges.

2. Store Your Cannabis In a Cool, Dry Place

Mold forms when marijuana plants are exposed to humidity. This can happen at various times before you consume it; while the plant is still growing, during the curing process, or as a result of poor storage at home.


The best way to avoid moldy weed after purchase is to provide a consistently dry environment for the product. Airtight containers like mason jars offer a good solution for storing cannabis, but you still need to take care not to open and close the jar too frequently or leave the lid open by accident.


Once you’ve found an appropriate airtight container, keep the sealed container in a cool and dark place and check your cannabis regularly for mold. If you keep it safely away from excessive heat, air, light, and moisture, your cannabis should last for several weeks. For long-term storage, it’s best to keep your cannabis in an airtight container in the freezer.

Can You Remove Mold Growth?

Though some people might suggest natural ways to remove mold from weed, you can never remove it completely because the spores will have spread to everything in the container. As mold on your weed can ruin the whole stash, the safest route is unfortunately to throw away all of the cannabis that may have become contaminated with mold spores.

Buying Medical-Grade Cannabis and Storing it Properly Can Help You Avoid the Negative Health Consequences of Consuming Moldy Weed

Regular cannabis consumers can do two main things to avoid smoking moldy weed: purchase only lab-tested medical-grade marijuana and use proper storage methods to keep your cannabis cool and dry. You can further reduce your risk by opting for more shelf-stable products like tinctures and capsules over inhalables like flower.


In addition, patients who consume marijuana to treat a debilitating health condition can maximize their access to safe, medical-grade products by applying for and renewing their medical card (in applicable states). If you have a compromised immune system, it’s worth doing everything you can to protect yourself from moldy or otherwise contaminated weed.

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