Jordan Michelle vapes a CBD oil made from hemp at the Cannabis World Congress Conference. Spencer Platt/Getty States around the country — 29 of them, plus Washington DC — have legalized medical marijuana.

The American public largely supports the legalization of medical marijuana. At least 84% of the public believes the drug should be legal for medical uses, and recreational pot usage is less controversial than ever, with at least 61% of Americans in support.

Even though some medical benefits of smoking pot may be overstated by advocates of marijuana legalization, recent research has demonstrated that there are legitimate medical uses for marijuana and strong reasons to continue studying the drug's medicinal uses.

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

There are at least two active chemicals in marijuana that researchers think have medicinal applications. Those are cannabidiol (CBD) — which seems to impact the brain without a high— and tetrahydrocannabinol (THC) — which has pain relieving properties and is largely responsible for the high.

But scientists say that limitations on marijuana research mean we still have big questions about its medicinal properties. In addition to CBD and THC, there are another 400 or so chemical compounds, more than 60 of which are cannabinoids. Many of these could have medical uses. But without more research, we won't know how to best make use of those compounds.

More research would also shed light on the risks of marijuana. Even if there are legitimate uses for medicinal marijuana, that doesn't mean all use is harmless. Some research indicates that chronic, heavy users may have impaired memory, learning, and processing speed, especially if they started regularly using marijuana before age 16 or 17.

For some of the following medical benefits, there's good evidence. For others, there's reason to continue conducting research.

Jennifer Welsh contributed to an earlier version of this story.