Use of e-cigarettes and other vaping products has increased sharply among US teens in recent years, but a large percentage appear to be using flavor-only, non-nicotine liquids when they vape, according to findings from a newly released survey reported by Medpage Today.

Two out of three teens who reported vaping at least once said their last vaping session involved “just flavoring” vaping liquids without nicotine, while one in five reported using vaping liquids with nicotine.

Findings from the National Institute on Drug Abuse’s (NIDA) 2015 Monitoring the Future survey suggest that the spike in e-cigarette use among teens does not represent an epidemic of new nicotine use in this age group, lead researcher Richard Miech, PhD, of the University of Michigan in Ann Arbor, told MedPage Today.