Vaping — use of electronic devices rather than burning tobacco to inhale nicotine — at one time seemed to be a good alternative to smoking. But something seems to have gone badly wrong.

Federal officials are investigating a spate of serious breathing illnesses linked to vaping in 33 states. More than 450 cases — five involving deaths — have been reported.

U.S. Centers for Disease Control and Prevention are urging those who engage in vaping to stop until more can be learned about the problem. It is good advice.

In the meantime, President Donald Trump announced Wednesday he intends to have flavored vaping liquids banned. These sweet-flavored liquids, from various fruit and floral scents to sweets, desserts and soft drink aromas, are one way young people get sucked into vaping, possibly getting them hooked on nicotine before they are old enough to legally smoke..

But what is most alarming and what may post the biggest hazard are the THC-laced vaping liquids which give you a marijuana-based buzz. These vaping materials seem to be most involved with the lung disease, illnesses and deaths connected to vaping in the past few months. Vaping materials are largely unregulated, but THC-laced liquids would seem to be especially dangerous.

The FDA on Monday warned Juul, the major e-cigarette maker, about claiming that vaping is a safe alternative to cigarettes. Juul is reportedly ignoring that for now.

Warnings and so on are not going to be effective without stricter regulation of what goes into the vaping liquid, and better studies of what those vapors do inside a pair of lungs.