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

33 states have legalized cannabis – that number is 46 states if we count laws with very limited access.

Even the NIH’s National Institute on Drug Abuse lists medical uses for cannabis.

But even though researchers have identified some fascinating potential benefits of medical marijuana so far, it’s something that’s still hard to study, making conclusive results tough to come by. The schedule I classification means it’s hard for researchers to get their hands on pot grown to the exacting standards that are necessary for medical research, even in states where it’s legal. Plus, no researcher can even try to make an FDA-approved cannabis product while it has that DEA classification, which removes some motivation to study the plant.

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

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.

With that caveat about research in mind, here are the medical benefits of marijuana.

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

A professor 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.

The findings were published in the Journal of Pharmacology and Experimental Therapeutics.

Related Article Learn More: Endocannabinoid System

During the research for his documentary interviewed the Figi family, who treats their daughter using a medical marijuana strain high in cannabidiol and low in THC.

There are at least two major active chemicals 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 very well for one expert in the field of cannabis study in Florida. 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.

CBD may also help prevent cancer from spreading, researchers at California Pacific Medical Center in San Francisco reported in 2007.

Cannabidiol stops cancer by turning off a gene called Id-1, the study, published in the journal Molecular Cancer Therapeutics, found. Cancer cells make more copies of this gene than non-cancerous cells, and it helps them spread through the body.

The researchers studied breast cancer cells in the lab that had high expression levels of Id-1 and treated them with cannabidiol. After treatment the cells had decreased Id-1 expression and were less aggressive spreaders. But beware: these are studies on cancer cells in the lab, not on cancer patients.

Other very preliminary studies on aggressive brain tumors in mice or cell cultures have shown that THC and CBD can slow or shrink tumors at the right dose, which is a great reason to do more research into figuring out that dose.

One 2014 study found that marijuana can significantly show the growth of the type of brain tumor associated with 80% of malignant brain cancer in people.

Medical marijuana users claim the drug helps relieve pain and suppress nausea — the two main reasons it’s often used to relieve the side effects of chemotherapy.

Researchers at Harvard Medical School suggested that that some of the drug’s benefits may actually be from reduced anxiety, which would improve the smoker’s mood and act as a sedative in low doses.

Published in the journal Molecular Pharmaceutics, found that THC, the active chemical in marijuana, slows the formation of amyloid plaques by blocking the enzyme in the brain that makes them. These plaques seem to be what kill brain cells and potentially cause Alzheimer’s.

A synthetic mixture of CBD and THC seem to preserve memory in a mouse model of Alzheimer’s disease. Another study suggested that in population-based studies, a THC-based prescription drug called dronabinol was able to reduce behavioral disturbances in dementia patients. Find a medical marijuana location in Florida near you.