Eight months ago Sanjay Gupta apologized for misleading the public on weed, declaring he’d been wrong about medical marijuana. He says he has come to see that for some sick people cannabis is the only thing that works.

The practicing neurosurgeon and CNN’s chief medical correspondent wrote in an op-ed for CNN Wednesday that since the cable news giant’s “Weed” documentary aired last August, he has continued to travel the world, meeting with hundreds of patients and scientists, and he’s even more supportive of medical marijuana than he was before.

“I am more convinced than ever that it is irresponsible to not provide the best care we can, care that often may involve marijuana,” Gupta wrote. “I am not backing down on medical marijuana; I am doubling down.”

Twenty states, including the District of Columbia, have legalized medical marijuana, but the drug remains illegal under federal law and classified as a Schedule I substance, which the federal government considers to be of “the most dangerous” variety “with no currently accepted medical use.”

“Neither of those statements has ever been factual,” Gupta wrote in the op-ed. “Even many of the most ardent critics of medical marijuana don’t agree with the Schedule I classification, knowing how it’s impeded the ability to conduct needed research on the plant.”

The American Epilepsy Society says that there are a million people for whom existing therapies do not control their seizures. The society recently said anecdotes about medical marijuana “give reason for hope” and said it supports “well-controlled studies that will lead to a better understanding of the disease and the development of safe and effective treatments.”

The NFL is following the science that suggests marijuana may help recovery from concussions.

Next week, CNN will premiere Gupta’s second installment of their “Weed” documentary, called “Cannabis Madness” where Gupta will unpack these ideas from his op-ed further and take a closer look at the politics behind legal weed.