Facing an explosion of vaping-related illnesses — linked to 805 cases and 12 deaths as of Thursday, September 26 — state officials from coast to coast are banning e-cigarette sales and telling people to stop vaping.

“We are seeing something that we have not seen before,” Charity Dean, acting public health officer of California, said this week in a statewide warning to refrain from vaping altogether, BuzzFeed News reports.

But critics fear these actions are overreaching. They worry that authorities are failing to distinguish between nicotine e-cigarettes like Juul and vaping devices containing THC, the ingredient responsible for the high from cannabis.

That difference matters, they say, because even though some studies have questioned the safety of vaping nicotine, it’s the latter that has been linked to most of the recent illnesses and deaths.

“There’s a risk in conflating these twin tragedies,” former FDA chief Scott Gottlieb warned in one of several tweets Wednesday. “They each require a very careful and deliberate approach if we’re going to stem these two crises.”

And yanking nicotine e-cigarettes off the market could have health consequences of its own. Ex-smokers who used them to quit may return to tobacco, which smoking experts fear would threaten a decade of progress in reducing smoking rates. Kids now addicted to nicotine because of vaping might turn to cigarettes. Cigarettes are linked to more than 480,000 US deaths yearly; by some estimates, 6.6 million premature deaths could be avoided over the next decade if smokers converted to e-cigarettes.