Figures from the UK Addiction Treatment Group shared with ITV News show that 5.1m adults in the UK vape daily and, in most cases, multiple times.
Of these, 2.6m are women.
Nearly 400,000 of them are pregnant.
Paul Baker, from Allan Carr’s Easyway, a stop-smoking organization told ITV News that it had seen increases in the number of people wanting assistance to quit vaping too. He said, “If we went back five years, it was probably 10 per cent of people were vapers. but at that time, they were dual users. That meant they smoked, and they vaped.
"Now it's just over 20 per cent. But actually what we're seeing is more and more people that have never smoked that have just purely vaped that are attending."
Across age groups, the popularity of vaping is also growing. Over a million users are 40-49 years old and 856,000 are aged 18-24.
Ann Pybus, a Brighton-based mother of three, was a smoker before she became addicted to vapes. She commented, “I wasn't controlling when I was vaping. It was definitely controlling me.
"My first vape lasted three months, so I thought, 'Oh, this is great. I've cracked this'. Then, it gradually built up and built up until I was smoking a vape a day for two years.
"For myself, it actually turned out to be a lot worse, I was certainly vaping an awful lot more than I was smoking."
Ann has attempted to quit vaping several times. She has now quit successfully through utilising professional advice.
Reflecting on how she feels now, Ann said, “I feel like I have been released from something that was bearing down on me. I don't feel that constant guilt that I'm killing myself."
Caitlin Notley, a professor and addiction scientist for Norwich Medical School, said, "No one's saying that vaping is completely harm-free.
"It's a very difficult balance, I think clearly, we want to support as many adults or people that smoke tobacco to switch to vaping as soon as we can because it's a deadly thing to do and incredibly harmful thing to health.
"At the same time, we don't want young people who've never smoked to take up vaping either."