The first death in the US from vaping has been recorded, say health officials.
They said a patient in Illinois who contracted a severe respiratory disease after vaping has died.
It is being considered the first death in the US that is linked to the alternative to smoking.
The Centers for Disease Control and Prevention (CDC) said it is investigating a mystery lung disease in the US that is linked to e-cigarettes.
It said there were 193 “potential cases” across 22 US states, many involving vaping THC, the main active compound in cannabis.
The cases were reported between June 28 and August 20.
All of those affected have been teenagers or adults who had used an electronic cigarette or some other kind of vaping device.
Doctors say the illnesses resemble an inhalation injury, with the lungs apparently reacting to a caustic substance. So far, infectious diseases have been ruled out.
The Illinois Department of Public Health (IDPH) said the adult patient who died was aged between 17 and 38 and was admitted to hospital after falling ill following vaping.
The state received the report of the death on Thursday, said Dr Jennifer Layden, the Illinois agency's chief medical officer.
Among the newest reports are two in Connecticut, four in Iowa and six in Ohio. Health officials are asking doctors and hospitals to tell state health officials about any possible vaping-related lung disease cases they encounter.
The Illinois agency said the number of people who contracted a respiratory illness after vaping had doubled in the past week, to 22.
"The severity of illness people are experiencing is alarming and we must get the word out that using e-cigarettes and vaping can be dangerous," said IDPH Director Dr Ngozi Ezike.
Electronic cigarettes have been described as a less dangerous alternative to regular cigarettes, but health officials have been worried about children using them.
Most of the concern has focused on nicotine, which health officials say is harmful to developing brains and might make youngsters more likely to take up cigarettes.
But some vaping products have been found to contain other potentially harmful substances, including flavouring chemicals and oils used for vaping marijuana, experts say.
A number of the people who got sick had vaped products containing THC, the high-inducing ingredient in marijuana. CDC officials said they do not have a breakdown of how many of the sick people vaped THC.