20 medical uses for marijuana

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It's that time of year when we take a look at the rapidly changing status of marijuana in the US.

Yes, the Drug Enforcement Agency still categorizes marijuana as a schedule I drug, one that has no accepted medical use, but since the late 1990s, a majority of Americans have thought medical pot should be legal. A majority support recreational legalization as well.

Washington D.C. and 24 states (plus Guam) have legalized medical marijuana (that number is even higher, no pun intended, if we count laws with very limited access).

But what do we know about the science behind medical uses of cannabis?

There seem to be some definite benefits. Even the NIH's National Institute on Drug Abuse lists medical uses for cannabis.

Yet it's hard to study marijuana's uses while the schedule I classification remains in place. It makes it difficult for researchers to get their hands on pot grown to the exacting standards that are necessary for medical research. Plus, there are hundreds of chemical compounds in the cannabis plant that could play a role in medical treatments, but for now, it's hard to know which aspect of the plant is causing an effect.

Using all the compounds in marijuana simultaneously is like "throwing 400 tablets in a cocktail and saying 'take this,'"Yasmin Hurd, a professor of neuroscience and psychiatry at Icahn School of Medicine at Mount Sinai, told Tech Insider last summer.

More research would identify health benefits more clearly and would also help clarify potential dangers. As with any psychoactive substance, there are risks associated with abuse, including dependency and emotional issues. Many doctors want to understand marijuana's effects better before deciding whether to recommend it or not.

With those caveats in mind, here are 20 of the medical benefits — or potential benefits — of marijuana.

Jennifer Welsh contributed to a previous version of this story.

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Marijuana can help control epileptic seizures.

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Marijuana use can prevent epileptic seizures in rats, a 2003 study showed.

Robert J. DeLorenzo, of Virginia Commonwealth University, gave marijuana extract and synthetic marijuana to epileptic rats. The drugs rid the rats of the seizures for about 10 hours. Cannabinoids like the active ingredients in marijuana, tetrahydrocannabinol (also known as THC), control seizures by binding to the brain cells responsible for controlling excitability and regulating relaxation.

More recent human studies have shown that cannabidiol (CBD), another major marijuana compound, seems to help people with treatment-resistant epilepsy.

It may help reverse the carcinogenic effects of tobacco and improve lung health.

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There's a fair amount of evidence that marijuana does no harm to the lungs, unless you also smoke tobacco, and one study published in Journal of the American Medical Association found that marijuana not only doesn't impair lung function, it may even increase lung capacity.

Researchers looking for risk factors of heart disease tested the lung function of 5,115 young adults over the course of 20 years. Tobacco smokers lost lung function over time, but pot users actually showed an increase in lung capacity.

It's possible that the increased lung capacity may be due to taking a deep breaths while inhaling the drug and not from a therapeutic chemical in the drug.

Those smokers only toked up a few times a month, but a more recent survey of people who smoked pot daily for up to 20 years found no evidence that smoking pot harmed their lungs.

It also decreases the symptoms of a severe seizure disorder known as Dravet's Syndrome.

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During the research for his documentary "Weed," Sanjay Gupta interviewed the Figi family, who treats their 5-year-old daughter using a medical marijuana strain high in cannabidiol and low in THC.

There are at least two major active chemicals in marijuana that researchers think have medicinal applications (there are up to 79 known active compounds). Those two are cannabidiol (CBD) — which seems to impact the brain mostly without a high— and tetrahydrocannabinol (THC) — which has pain relieving (and other) properties.

The Figi family's daughter, Charlotte, has Dravet Syndrome, which causes seizures and severe developmental delays.

According to the film, the drug has decreased her seizures from 300 a week to just one every seven days. Forty other children in the state are using the same strain of marijuana (which is high in CBD and low in THC) to treat their seizures — and it seems to be working.

The doctors who recommended this treatment say that the cannabidiol in the plant interacts with the brain cells to quiet the excessive activity in the brain that causes these seizures.

As Gutpa notes, a Florida hospital that specializes in the disorder, the American Academy of Pediatrics, and the Drug Enforcement agency don't endorse marijuana as a treatment for Dravet or other seizure disorders.