Wouldn’t it be nice if there were a simple “This is your immune system on cannabis — any questions?” meme? Unfortunately, when it comes to the effects of cannabis on your immune system, it’s just not that easy. While scientists have been learning a lot about cannabidiol’s (CBD) health benefits, the research about cannabis immune system effects is spotty and somewhat contradictory.

Can Cannabis Cure the Common Cold?

Probably not, according to Laura Borgelt, a professor in the department of clinical pharmacology and family medicine at the University of Colorado. Despite the fact that she’s been researching the therapeutic uses of cannabis for years, she hasn’t found any studies or research on that particular subject. In fact, thanks to marijuana’s official classification as a Schedule 1 substance, researchers often find it difficult to get permission to conduct real research into the effects of cannabis on the immune system — or for any other medical use. That’s not to say there’s no research on CBD health benefits. There are thousands of small, independent studies. Most have what researchers call “significant design flaws,” but their general trend suggests that cannabis may enhance immune system function.

Cannabis and Your Immune System: What We Know So Far

In a nutshell, the various active compounds in cannabis — most notably tetrahydrocannabinol (THC) and cannabidiol (CBD) — may suppress your immune system. This is actually quite beneficial for those with certain medical conditions. There’s a growing body of research supporting the use of THC and other cannabis-derived chemicals for autoimmune disorders such as Crohn's disease, multiple sclerosis and rheumatoid arthritis. Scientists believe these disorders — and many more like them — are caused by an overactive immune system. Thus, “improving” your immune system means making it less sensitive so it stops attacking the body’s own tissues. Similarly, medical marijuana may be helpful to people who undergo organ transplants.

Cannabis Reduces Inflammation and May Boost Your Immune System

So if cannabis suppresses the immune system, does it make you more susceptible to, say, the flu or the common cold? It may sound like common sense, but scientists say it’s more complicated than that. A lot of the research into the health effects of CBD has been conducted on patients with severely compromised immune systems — those with HIV, hepatitis B or, surprisingly, the ebola virus. Overall, researchers have found that treatment with medical cannabis and cannabinoids (synthetic cannabis compounds) doesn’t increase the number of virus cells in the body or the number of other infections that patients contract. In fact, they believe that weed’s known anti-inflammatory effects may reduce the damage that so-called opportunistic diseases do to the body.

Cannabis and Cancer — Not Just for Symptoms Anymore

One of the best known uses for medical weed is to help cancer patients deal with the effects of chemotherapy. A July 2018 review published in the British Journal of Pharmacology concluded that THC and cannabinoids derived from cannabis may actually fight cancer. The researchers found evidence that cannabis might stop cancer cells from dividing, keep them from invading nearby tissues (metastasizing) and may block blood supply to tumors. In addition, it may stimulate the brain, the immune system and the hormone system to more effectively fight the cancer cells.But what about that common cold? Well, your trusty CBD oil may not protect you from the bug going around the office, but it probably won’t hurt. It might even help. Dr. Jordan Tishler, who runs a Massachusetts-based practice focusing on medical cannabis use, notes that regular small doses of cannabis — microdosing — can improve your mood and reduce stress, two factors that have a proven connection to immune system function.

Deb Powers is a freelance writer living in Massachusetts, a state that is in the process of legalizing recreational marijuana. She has researched and written on edibles and CBD for wellness, and is working with a small local group pursuing a retail license in her city.