"I think we have been terribly and systematically misled in this country for some time, and I did part of that misleading," he said.
Gupta, a neurosurgeon, told CNN host Piers Morgan that research in the U.S. focused on negative effects of the drug, while studies from the rest of the world have shown evidence of marijuana's benefits.
He noted the high rates of prescription drug deaths, and said, "I couldn’t find one documented case of someone dying of a marijuana overdose."
"I think it is irresponsible of the medical community not to offer this as an alternative."
Both Gupta and Morgan admitted they'd tried marijuana, though Gupta said he "didn’t particularly care for it," saying it made him anxious.
Gupta's documentary "Weed" will air on CNN Sunday, profiling the fight over medical marijuana and the progress of the pot industry.