Table 3.

Summary of the criteria for e-cigarette addiction and examples of their presence and absence.

Criterion	Themes	Example reports of presence	Example reports of absence
1	Loss of control	“I’m actually annoyed by my vaping. I vape quite a lot and reach for my e-cigarette almost automatically.”	“I vape 18mg just to avoid vaping constantly.”
2	Unsuccessful attempts to reduce	“I increased the nicotine from 0.5 to 2mg because it was not possible to go with less or no nicotine for me.”	“I started off with a 6mg dose but decreased it daily. At one point I vaped less than 6mg and then I could live with no nicotine at all. I also think without nicotine the liquid tastes best.”
3	Expenditure of time	“When I’m at home I vape constantly, and when I leave the house I always bring more than one vape with me.”	—a
4	Craving	“When I imagine not being able to use my e-cigarette, I get anxious and instantly have to vape.”	“I once went to a vaper meeting and went the whole evening without my e-cigarette. No one noticed and I did not feel craving and had such a good evening.”
6	Social problems related to use	“My wife doesn’t like it when I vape. When I vape in the house she complains or looks disgusted.”	“My manager and I discussed vaping at work and he is okay with it as long as no one complains. Some of my colleagues think my office smells really good because of the e-cigarette.”
7	Restriction of social activities	“Since I spend some money on my hardware, I had to stop my hobby for the time being.”	—
9	Health problems	“What I find very annoying is that I constantly feel like I have a cough. It feels like an allergy, which means I sneeze often, and I cough green mucus in the mornings.”	“Since I transitioned to the e-cigarette my mental and physical health has improved significantly. I do more sports and my lungs and heart don’t complain anymore when I work out. I used to get panic attacks and was super nervous but not anymore!”
10	Tolerance	“As you know, I have been using an e-cigarette for a bit more than a month now. Now, I do not get a buzz from vaping anymore. So, I have put more nicotine into my mix again.”	“I am noticing that an increased nicotine dosage has negative effects...I have trouble sleeping, a higher blood pressure, palpitations and so on.”
11	Withdrawal	“I often work several hours without a break and cannot vape during that time. Sometimes I get quite angry and my lung complains.”	“I believe I could stop vaping anytime. I actually was able to stop smoking more than once. It did not affect me at all, I did not get nervous or anything. In contrast to when I smoked cigarettes, I am now able to concentrate on long books without vaping.”

^aNot available. Reports of absence for these themes were not found and examples were not coded.