A man who became a prolific vaper for health reasons has switched back to smoking cigarettes in a bid to curb his nicotine addiction.
US man Lucas McClain smoked cigarettes in high school but turned to vaping after he heard it was a safer alternative.
But now the 21-year-old is struggling to overcome his nicotine addiction after vaping made his dependency to nicotine even worse, CNN reported.
His vape of choice became the Juul, but the king of electronic cigarettes came with a king-size nicotine hit, unbeknown to McClain.
"Juul made my nicotine addiction a lot worse," the 21-year-old told CNN.
"When I didn't have it for more than two hours, I'd get very anxious."
Just last month McClain bought his first pack of cigarettes in years, tweeting, "Bought a juul to quit smoking cigarettes, now I'm smoking cigarettes to quit the Juul. #circleoflife."
One pod of Juul, which contains 200 puffs, is packed with as much nicotine as a whole pack of cigarettes.
McClain told CNN he could get through one pod of Juul in three hours.
The trend of vaping has worried health experts, who are researching more than 450 cases of lung disease across 33 states in the US directly linked to vaping.
So far, six people have died.
But converting back to cigarettes is also an alarming health officials because cigarettes contain toxins and chemicals that are dangerous to users' health.
Others have come forward on Twitter revealing they've had issues since turning to the vape and have gone back to using cigarettes.
"Isn't it ironic that to quit juul I bought cigarettes," says one Twitter user.
Another said it was strange she used vaping to quit smoking but feels "far more addicted to my Juul than I ever was to cigs".
Dr Elisa Tong, an associate professor of medicine at the University of California-Davis, understands why people are turning back to cigarettes, but told CNN alternatives are just as dangerous as one another.
"What they're doing is trying to taper down super high levels of nicotine," she said. "Unfortunately, manufacturers don't have a manual on how to quit their devices."
In an alarming case of e-cigarette use, last month an 18-year-old student-athlete from the US was hospitalised after vaping for more than a year and a half.
Now his lungs are similar to those of a 70-year-old adult, doctors told him.
"It was scary to think about that -- that little device did that to my lungs," Adam said, remembering the news from his doctors about his lung health.
Adam is among the hundreds of e-cigarette users in the United States who have been sickened with mysterious vaping-related lung illnesses, many of them young people.
Investigators haven't yet identified the cause of the illnesses. Amid calls for more regulation, the Trump administration now plans to remove flavoured e-cigarettes - except tobacco flavour - from the marketplace.