There is much about CBD that is still unknown. It has largely gone unstudied because, until 2018, it was considered a schedule I drug by the U.S. Drug Enforcement Administration (DEA). A schedule I drug is a drug that has been declared illegal by the DEA because of safety concerns over its potential for abuse and because there is no accepted medical use for it. Then, in September 2018, the DEA updated CBD’s status to become a schedule V drug. Schedule V drugs have a lower potential for abuse and are deemed to have some medical use.
CBD comes from cannabis plants called hemp that are specifically grown with high levels of CBD and low levels of THC. Cannabis plants grown with high levels of THC are usually called marijuana. CBD comes from oil that is extracted from the cannabis plant. That oil can then be ingested as a liquid, a capsule, a gummy, or inhaled through vaping. It can also be added as an ingredient in such products as lotions and skin patches.
What is CBD?
You may find stories online of people discussing the benefits of CBD as a cancer treatment or as relief for side effects. Please remember that such personal stories, while they may be well-meaning, are shared without scientific study and do not constitute evidence. The safety and efficacy of CBD for people with cancer still has to be proven in large, randomized, controlled clinical trials.
You may also be wondering if CBD is legal in your area. Some states allow the sale and possession of cannabis, including CBD and THC, for medical and recreational use. Others have stricter regulations, so state-by-state laws should always be learned before transporting CBD across state lines. Things are more complicated at the federal level. In 2018, the U.S. government recognized that hemp can be grown and manufactured legally as part of the Farm Act. Hemp can be used to make things like rope and clothing, in addition to CBD oil. In other words, hemp is no longer a controlled substance, which means it is not regulated by the government. This means that consumers have to evaluate the safety and quality of CBD products on their own. Some CBD, for example, may have much higher levels of THC than what is labeled.
There are 2 synthetic cannabis medications, nabilone (Cesamet) and dronabinol (Marinol or Syndros), that are FDA-approved to treat nausea and vomiting related to chemotherapy. These medications are made in a laboratory.
Dr. Hou: When CBD is taken by mouth, some amount is absorbed and becomes available in the blood. There are cannabinoid receptors throughout the human body, and when CBD binds to them, that can trigger biological effects. But the downstream effects are still unclear because currently, there are very few human data. Other edible products containing CBD are likely absorbed and metabolized in a similar manner. There is, however, limited absorption through the skin with topical CBD oil.
You and your MSK care team should make a joint decision on using cannabis.
Dr. Raghunathan: CBD is not psychoactive in the same way that marijuana is. It doesn’t act on the cannabinoid receptors in the central nervous system, which is how THC works. However, it is possibly psychoactive because it works on serotonin receptors, and anything that affects mood is psychoactive. CBD has been studied in mice and seems to affect sleep-wake cycles. But CBD can be unexpectedly psychoactive and sedative because it’s not well-regulated. Studies have shown that some products that claim to be pure CBD actually have THC and other dangerous contaminants, such as opioids.
How can people with cancer use CBD?
The law also establishes retail licenses, opening the door for dispensaries selling marijuana online and in retail stores.
New York State is the latest to legalize the recreational use of marijuana for adults.
Dr. Hou: We need more research to assess the safety and effects of CBD. And we need to take a closer look at potential herb-drug interactions, which is especially important for people receiving chemotherapy.
Dr. Raghunathan: While legalization and regulation may change the accessibility and/or quality of all cannabis products, it doesn’t change the lack of scientific evidence. Unfortunately, we still don’t know enough about the benefits of these products for people with cancer. There is a lot of research happening in Canada and Australia because regulations around its use there have changed. It will be interesting to see what comes out of that. In the meantime, you and your doctor should discuss the potential benefits and harms of using anything with cannabis for medical purposes.