Skip to main content

By Heather Stringer updated 12/2021

When parents started asking child neurologist Robert Carson, MD, PhD, whether they should try using medical marijuana to treat their children who were suffering from severe epilepsy, Carson knew it would be hard to answer this question.

As a Schedule 1 drug in the Drug Enforcement Administration’s classification system, marijuana—or cannabis—had not been extensively studied by researchers. Deemed a drug with no currently accepted medical use and a high potential for abuse, marijuana is in the same category as heroin and LSD. To better understand whether the excitement about cannabis for epilepsy was warranted, Dr. Carson and his colleagues at Vanderbilt University launched a study in which they evaluated records for 108 pediatric patients with epilepsy who had added CBD (cannabidiol) oil—one of the compounds in marijuana—to their treatment regimen. Their parents had purchased the products online, at a medical marijuana dispensary or through some other means.

He discovered that about 40 percent of these patients experienced a 50 percent reduction in the number of seizures, and 10 percent stopped having seizures altogether.[i] More than 20 percent reduced their doses of anti-seizure medication. “Clearly there was a benefit for some patients, but there still is no data showing that cannabis is better than other medications for epilepsy,” says Dr. Carson, an assistant professor of pediatric neurology at Vanderbilt University. “When children are having 90 to 400 seizures per month and other medications have failed, cannabis becomes an option worth trying.”

Although Dr. Carson’s study was small and observational, larger studies were simultaneously underway to evaluate whether Epidiolex, an oral CBD solution, could be used to treat two rare and severe forms of pediatric epilepsy known as Lennox-Gastaut syndrome and Dravet syndrome. In June 2018, Epidiolex became the first Food and Drug Administration (FDA)-approved drug that contains a purified form of a substance derived from marijuana.

For pioneers leading the way in the field of cannabis research, the Epidiolex story demonstrates the importance of gathering evidence that can help guide patients who are often experimenting with medicinal cannabis before it has been adequately studied.

“This is a good example of the kind of work that needs to be done to test whether observations and anecdotal evidence stands up in clinical trials,” says Jason Busse, PhD, associate director of the Michael G. DeGroote Centre for Medicinal Cannabis Research in Canada.

The Complications of Cannabis

Cannabis contains more than 100 active biological ingredients, and the two most well-known compounds are cannabinoids known as CBD and THC, or tetrahydrocannabinol. “THC creates the euphoric high and has the potential to be addictive, but CBD does not,” says Busse an associate professor of anesthesia research at McMaster University in Canada. “And CBD has some important anti-inflammatory properties.”

Humans have a natural endocannabinoid system that plays an important role in the central and peripheral nervous systems, and the CB1 and CB2 receptors in the brain are part of that system. Cannabis stimulates these receptors and activates them for longer periods of time than the natural system, explains Busse.

Cannabis is difficult to study in part because there are tight government controls over studies that test Schedule 1 drugs in humans, says Dr. Charles Pollack, MD, director of the Lambert Center for the Study of Medicinal Cannabis & Hemp at Thomas Jefferson University in Pennsylvania. Obtaining cannabis for federally funded studies is also expensive and difficult because the National Institute on Drug Abuse is the only legal source for research-grade marijuana, says Dr. Pollack, associate provost of Innovation in Education at Thomas Jefferson University. Studying CBD may become easier in the near future, though, now that the FDA has approved Epidiolex, a drug that contains CBD. There is hope that the DEA will consider downgrading CBD to a Schedule II or III classification because the compound now has an approved medicinal use.

One of the areas many researchers are hoping to further study is the use of medical marijuana to treat pain. “Unfortunately, there are not great options for a lot of patients who suffer from chronic pain,” Busse says. “Anecdotally I’ve heard stories from patients who have acquired cannabis, and report that it provides an important benefit.”

To better understand the potential therapeutic benefits of cannabis, the National Academies of Sciences, Engineering and Medicine analyzed data from 10,000 scientific abstracts, and there was conclusive and substantial evidence that cannabis is effective for treating chronic pain in older adults, according to the 2017 report. (2)

Several studies from the Center for Medicinal Cannabis Research (CMCR) at the University of California, San Diego, suggest that inhaled cannabis has pain-relieving effects in the short-term for neuropathic pain, a disorder caused by illness or injury that leads to chronic nerve pain, explains J. Hampton Atkinson, MD, co-director of the CMCR. In one study, researchers from the center reviewed data from 178 patients in randomized controlled trials, and they found that about one in five patients experienced short-term reductions in chronic neuropathic pain. (3)

Dr. Nick Spirtos, MD, an oncologist at the Women’s Cancer Center of Nevada, started investigating the use of cannabis for treating cancer-related pain, and he conducted a study to explore whether a marijuana-based syrup could reduce pain. Twenty-five patients who had been taking opiates regularly were given the syrup every four to six hours for a month, and they only took opiates for breakthrough pain. Spirtos found that the patients decreased their opiate use by 75 percent, and 25 percent stopped taking opiates completely. The possibility of substituting cannabis for opioids has garnered attention nationwide, and a study published in the Journal of the American Medical Association in April found a 14 percent reduction in opioid prescriptions in states that had easy access to medical marijuana. Currently, medical marijuana is legal in 30 states.

Although cannabis is safer than opioids because users cannot overdose on the drug, clinicians and researchers agree that more evidence is needed before patients consider using cannabis as a substitute drug for pain. “We were at this point in the late 80s and early 90s when we were desperate to help people with chronic pain, and doctors started prescribing opioids,” Busse says. “We want to learn a lesson from that experience. With so much limited information about cannabis, it’s difficult to know if it represents a good treatment for patients who are on it for a long period of time.”

The Limitations of Medical Marijuana

In addition to epilepsy and pain, cannabis has also been shown to help people on chemotherapy who are suffering from nausea and vomiting, according to the report from the National Academies of Sciences, Engineering and Medicine. Dr. Spirtos witnessed this trend in patients who were not responding to standard antiemetics (drugs prescribed to treat nausea and vomiting).

“Patients were doing this on their own when other treatments failed, and cannabis relieved the nausea and vomiting across the board,” he says.

Scroll to Continue



Do You Have the Perfect Nose?

The British Association of Aesthetic Plastic Surgeons (BAAPS) regularly releases an annual audit, and the figures from 2018 showed that some 28,000 procedures took place in 2018.

Eye Health

How Your Eyes Change as You Age

Eye health is something that many of us take for granted, but which also impacts us widely.

Pink Ribbon

4 Important Advances in Breast Cancer Treatment through the Years

Breast cancer, which afflicts more than 7 million people around the globe, is the world’s most prevalent cancer and the most common form of cancer among women.

The FDA has also approved Marinol (dronabinol), which includes a synthetic form of THC. Marinol can be an appetite stimulant for patients with AIDS who are suffering from excessive weight loss and reduce nausea and vomiting symptoms associate with chemotherapy in cancer patients.

The report from the National Academies also concluded that there was substantial and conclusive evidence that oral cannabinoids can improve multiple sclerosis spasticity symptoms. The American Academy of Neurology (AAN) came to the same conclusion after conducting a review of scientific research, but cannabis did not appear to be helpful in treating drug-induced movements in Parkinson’s disease or motor problems in Huntington’s disease, according to the AAN’s report. (4)

There have also been studies showing that cannabis is not effective in improving symptoms associated with dementia, intraocular pressure in glaucoma and depression in people with chronic pain or multiple sclerosis, according to the report from the National Academies.

The FDA has already approved Marinol, which includes a synthetic form of THC. Marinol can be an appetite stimulant for patients with AIDS who are suffering from excessive weight loss, and reduce nausea and vomiting symptoms associated with chemotherapy in cancer patients.

The longer-term impact of widespread medical marijuana use has yet to be studied, but Busse has been intrigued by results from his team’s recent review of literature. One study showed a reduction in suicide rates among men ages 20 to 39 in U.S. states that had legalized medical marijuana.[v] Researchers speculate that marijuana may be helping this age group of men cope with stressful life events, but more research is needed to understand if there is a correlation between the two, Busse says. It’s patterns like this that are motivating researchers to advocate for more studies to understand the benefits and potential harms of medicinal cannabis.

“Some advocates are taking findings from animal studies and conflating this to clinical benefits in humans,” Busse says. “We need to help the public distinguish the signal from the noise, and we hope to do that by putting together more formal clinical trials in the years to come.”

Side Effects of Smoking Marijuana Every Day What Do We Know?

Marijuana is used now used to manage nausea and weight loss, treat glaucoma, and reported to help patients suffering from pain and wasting syndrome associated with HIV, as well as irritable bowel syndrome, Crohn's disease and other conditions where the final common pathway is chronic pain. Smoking marijuana is often perceived to be “risk free” but it’s not. Here is what we know about the regular use of marijuana. (6)

Impaired Senses-Mood and Behavior Changes - Daily marijuana use can lead to feelings of fatigue or apathy; feelings of anxiety, paranoia, or panic; temporary hallucinations and trouble taking care of oneself. Individuals may also disconnect from activities or people they once enjoyed and experience impaired memory and confusion.

Respiratory Diseases - Chronically inflamed airways from smoking can result in a chronic cough, sore throat, or runny nose, and put the user at a higher risk for respiratory diseases.

Marijuana Use Disorder - Smoking marijuana daily carries with it very real potential for addiction. The National Institute on Drug Abuse estimates that between 9% and 30% of those who use marijuana regularly will develop marijuana use disorder. Habitual users can experience reduced academic performance, job loss, legal consequences, depression, anxiety, and in several cases, psychotic symptoms requiring hospitalization.

You May Have an Increased Risk of Heart Issues - Marijuana has been associated with triggering heart attacks in young male patients. Smoking marijuana has been shown to increase the risk of MI onset by a factor of 4.8 for the 60 minutes after marijuana consumption, and to increase the annual risk of MI in the daily cannabis user from 1.5% to 3% per year."

Functional and Structural Changes in Your Brain - Functional MRI studies demonstrate functional and structural changes in brain areas involved in reward processing after chronic cannabis use and in the processing of emotion. Some studies show a higher incidence of schizophrenia in chronic adolescent and teenage use of marijuana.

Pregnancy Issues - Marijuana use during pregnancy can be harmful to your baby's health. According to the Centers for Disease Control chemicals in marijuana (in particular, tetrahydrocannabinol or THC) pass through your system to your baby and can harm your baby's development. (7) "Some research shows that using marijuana while you are pregnant can cause health problems in newborns— including low birth weight.

Withdrawal - Withdrawal from cannabis seems to induce a lack of motivation. Cognitive dysfunction and memory problems are other potential problems such as abnormal response to stress. A clinical diagnosis of cannabis withdrawal includes irritability, anger or aggression, nervousness or anxiety, sleep difficulty, decreased appetite or weight loss, restlessness, depressed mood, and physical symptoms causing significant discomfort such as shakiness or tremors, sweating, fever, chills, and headaches. (7)


  1. Porcari GS, Fu C, Doll ED, Carter EG, Carson RP, Efficacy of artisanal preparations of cannabidiol for the treatment of epilepsy: Practical experiences in a tertiary medical center, Epilepsy & Behavior, 2018 March, 80:240-246. Available here
  2. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research, National Academies of Sciences, Engineering, and Medicine. Available at:
  3. Wilsey B, Marcotte TD, Deutsch R, Zhao H, Prasad H, Phan A. An Exploratory Human Laboratory Experiment Evaluating Vaporized Cannabis in the Treatment of Neuropathic Pain from Spinal Cord Injury and Disease. J Pain. 2016 Jun 7. pii: S1526-5900(16)30072-4. Available here
  5. D Mark Anderson, Daniel Rees, Joseph Sabia, Medical Marijuana Laws and Suicides by Gender and Age, American Journal of Public Health, 2014 December; 104(12): 2369-2376.