Over the years, research has yielded results to suggest that marijuana may be of benefit in the treatment of some conditions. These are listed below.

Chronic pain

Last year, a large review from the National Academies of Sciences, Engineering, and Medicine assessed more than 10,000 scientific studies on the medical benefits and adverse effects of marijuana.

One area that the report looked closely at was the use of medical marijuana to treat chronic pain. Chronic pain is a leading cause of disability, affecting more than 25 million adults in the U.S.

The review found that marijuana, or products containing cannabinoids — which are the active ingredients in marijuana, or other compounds that act on the same receptors in the brain as marijuana — are effective at relieving chronic pain.

Alcoholism and drug addiction

Another comprehensive review of evidence, published last year in the journal Clinical Psychology Review, revealed that using marijuana may help people with alcohol or opioid dependencies to fight their addictions.

But this finding may be contentious; the National Academies of Sciences review suggests that marijuana use actually drives increased risk for abusing, and becoming dependent on, other substances.

Also, the more that someone uses marijuana, the more likely they are to develop a problem with using marijuana. Individuals who began using the drug at a young age are also known to be at increased risk of developing a problem with marijuana use.

Depression, post-traumatic stress disorder, and social anxiety

The review published in Clinical Psychology Review assessed all published scientific literature that investigated the use of marijuana to treat symptoms of mental illness.

Its authors found some evidence supporting the use of marijuana to relieve depression and post-traumatic stress disorder symptoms.

That being said, they caution that marijuana is not an appropriate treatment for some other mental health conditions, such as bipolar disorder and psychosis.

The review indicates that there is some evidence to suggest that marijuana might alleviate symptoms of social anxiety, but again, this is contradicted by the National Academies of Sciences, Engineering, and Medicine review, which instead found that regular users of marijuana may actually be at increased risk of social anxiety.

Cancer

Evidence suggests that oral cannabinoids are effective against nausea and vomiting caused by chemotherapy, and some small studies have found that smoked marijuana may also help to alleviate these symptoms.

Some studies on cancer cells suggest that cannabinoids may either slow down the growth of or kill some types of cancer. However, early studies that tested this hypothesis in humans revealed that although cannabinoids are a safe treatment, they are not effective at controlling or curing cancer.

Multiple sclerosis

The short-term use of oral cannabinoids may improve symptoms of spasticity among people with multiple sclerosis, but the positive effects have been found to be modest.

Epilepsy

In June 2018, the Food and Drug Administration (FDA) approved the use of a medication containing cannabidiol (CBD) to treat two rare, severe, and specific types of epilepsy — called Lennox-Gastaut syndrome and Dravet syndrome — that are difficult to control with other types of medication. This CBD-based drug is known as Epidiolex.

CBD is one of many substances that occurs in cannabis. It is not psychoactive. The drug for treating these conditions involves a purified form of CBD. The approval was based on the findings of research and clinical trials.

study published in 2017 found that the use of CBD resulted in far fewer seizures among children with Dravet syndrome, compared with a placebo.