Medical marijuana is moving slowly but surely into the medical mainstream.

The latest news: Epidiolex, an experimental drug made by GW Pharmaceuticals from a purified marijuana extract, reduces seizures by 39% in children with a rare form of epilepsy, Dravet syndrome (severe myoclonic epilepsy of infancy), according to a preliminary report. If it’s approved by the FDA, it would be the first marijuana-derived US-approved medicine.

The key ingredient—cannabidiol (CBD). Unlike its more famous cousin tetrahydrocannabinol (THC), it doesn’t produce a high, but it has raised many hopes in the epilepsy community. The marijuana compound became famous a few years ago when CNN’s Sanjay Gupta, MD, told the story of Charlotte Figi, a girl with Dravet syndrome whose seizures went from 300 a week to one after she started being treated with CBD-rich marijuana. Charlotte’s Web, a CBD-rich hemp oil produced by a company in Colorado, is now sold for therapeutic purposes for epilepsy that doesn’t respond to medications. Because it’s so low in THC that it actually qualifies as hemp oil, it can be sold without a prescription and by mail.

For now, many patients prefer the whole-plant extract approach to the purified pharmaceutical. That may change, at least for some patients and doctors, as prescription drugs come onto the market.

But one thing is clear—the age of medical marijuana is evolving rapidly. To learn more, see Bottom Line’s article, The Surprising Truth about Medical Marijuana for 11 Health Conditions as well as this guide.