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Marijuana and COVID-19: What a Doctor Wants You to Know

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Neha Pathak, MD - Blogs
By Neha Pathak, MDBoard-certified internistApril 20, 2020
From the WebMD Archives

With the rapid spread of the new coronavirus throughout the globe, people are looking for ways to protect their health and lessen the risk of COVID-19 complications. Because having damaged lungs is one of the main risk factors for complications, smoking of any kind is being discouraged by health experts.

As it's become legal in some parts of the U.S., many people use cannabis products for both medical and recreational purposes, and some who smoke, inhale, or vape marijuana are wondering if it’s safer to switch to alternatives, like “edibles” to protect their lungs and immune systems.    

Just like the developing science around COVID-19, the facts around cannabis are also murky. To help me navigate the data, I turned to several scientists behind the 2017 National Academy of Sciences (NAS) report on the health effects of cannabis and related products. According to Daniele Piomelli, PhD, professor of anatomy and neurobiology, and Chair in Neuroscience at the University of California, Irvine School of Medicine, “we don’t have a lot to go on” when it comes to marijuana and the risk for viral infections like COVID-19, but there are definitely some steps we can take when it comes to reducing harms from marijuana use.

Are edibles (and other non-inhaled forms) safer than smoking marijuana?

There is a lot of evidence that points to an association between long-term cannabis smoking and lung damage causing chronic cough and phlegm production. There’s also evidence that when you stop, these lung symptoms can improve. “Are edibles safer than smoked cannabis? Yes, they are safer to the lung – that is a slam dunk,” says Piomelli. He stresses, however, that they are not risk free. He points out that it is almost impossible to know for sure how much THC (the active ingredient that gives the “high”) is in edible forms like gummies and chocolates because manufacturers are not bound by rules to abide by what is listed on the label. (While this is the case in most states, several states that have legalized cannabis use require that manufacturers lab test products to ensure the dosage information on the label is accurate for all legally sold products.)

When someone smokes, they have a much better sense of when to stop based on how they are feeling. This is not the case for edibles, says Piomelli. “One or two hours later, all of a sudden, it can hit like a sledgehammer – you can have a ‘bad trip’ (and) once you have it there is no undoing it. You have to wait it out until it is metabolized and out of your system.” Side effects from overdose, like paranoia, panic, and nausea are mostly a risk for people who are switching to new products, where people don’t know how their bodies will react. Another important point is that edibles usually are high in sugar, which is not ideal for maintaining a healthy lifestyle.

Does cannabis have beneficial effects that help with anxiety?

There is growing concern about the mental health impacts of the coronavirus pandemic. Add social isolation from strict lockdowns to economic stressors, and there is growing evidence that people are looking for ways to curb their anxiety.

A recent study showed that prescriptions for anti-anxiety medications, anti-depressants, and anti-insomnia medicines increased after the WHO declared a global pandemic. There’s also evidence that alcohol sales and alcohol consumption have increased during this time.

Piomelli says “It’s understandable that people may be using more cannabis at home these days. Once the numbers are found out, we will have more data on this.” He suggests that cannabis products that people are comfortable and familiar with may be reasonable in moderation, and are likely safer than alcohol and other psychoactive substances. According to the NAS report, people should be aware, however that regular, long-term use may increase the risk for developing social anxiety disorder and heavy users are more likely to report thoughts of suicide.

It’s also important to realize that if you are using cannabis to “self-medicate” for anxiety, you should reach out to a professional for help.

How does cannabis affect the immune system?

Given the COVID-19 pandemic, there’s a lot of interest around maintaining a healthy immune system. The NAS report delved into the evidence around the effects of cannabis on the immune system and the susceptibility to viral infections.

There is an intriguing finding noting a small body of evidence that shows that cannabis may decrease the production of several inflammatory cytokines (immune system proteins). This is an important area of study right now, because scientists have found that in many of the most severe cases of COVID-19, there seems to be an over-production of these cytokines, also known as “cytokine storm,” which prompts the body to attack its own cells and tissues instead of fighting the virus.

It’s really important to know, however, that the immune system is made up of a variety of cells and chemical signalers that interact through a complex interplay, so it’s hard to say where cannabis may help tamp down the immune system and where it may hurt by increasing the risk of infection.

Piomelli points out that a few more scientific papers have been released since the 2017 NAS report looking at cannabis and viral infections. One particular study looked at the evidence not only around THC containing cannabis but also cannabidiol (CBD). CBD is also found in the cannabis plant, but unlike THC, does not have the properties that cause the “high.”  The findings from this study are encouraging and will hopefully prompt further study because there may be a chance that CBD can help control inflammation and help manage certain viruses – but the evidence is still scant.

“The point is we don’t enough data. I wish we did,” says Piomelli.

Major takeaways:

  • Inhaling, smoking, or vaping cannabis products in the face of COVID-19 is not recommended.
  • If cannabis use is legal where you live and you want to switch to edibles or other forms of cannabis, make sure it’s a known entity that you have experience with, and use only in moderation. (Remember that these products can be high in sugar content.)
  • With edibles, there is a higher risk of a “bad trip,” especially for those who have not used them in the past.
  • There is not enough evidence to know the effects of cannabis on the immune system or on the susceptibility to viral infections.
  • Consider other ways of managing anxiety. Creating a routine that includes exercise, proper nutrition, meditation, and regular social interactions can help manage stress in a healthy way.
  • If you are using cannabis to treat anxiety, reach out for help from a mental health professional

Editor's note: This post has been updated to acknowledge that edibles may be regulated in some states.


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About the Author
Neha Pathak, MD

Neha Pathak, MD, is a board-certified internal medicine doctor and part of WebMD's team of medical editors responsible for ensuring the accuracy of health information on the site. Before joining WebMD, Pathak worked as a primary care physician at the Department of Veterans Affairs and was an assistant professor of medicine at Emory University in Atlanta.

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