After 3 years on the e-cig, I've had to stop. I had major breathing problems with it. On singulair and needing rescue inhaler several times per day, and waking up in the middle of the night trying to breath and wheezing. I thought I was doing a good thing and didn't touch a cigarette for 3 years. However, I found myself vaping constantly because it was just too easy. I was not a heavy smoker, 5 cigs per day at most, and never had asthma or any breathing issues. It was getting worse and worse, and I felt awful. After thinking about it a lot, I realized that my breathing problems started about 2 months after switching to e-cigs. I decided to stop the e-cigs but my nicotine addiction was too much so I went back to my 3-5 cigs per day and within a week, my breathing is back to normal. It's been a month now and I don't need the singulair or the inhaler anymore at all. I don't wake up in the middle of the night gasping for air and wheezing, and I don't get out of breath after going up the stairs. I feel like myself again. I'm disappointed because I wanted the e-cigs to be a healthy alternative for me but it really made me sick. I'm not saying this will happen to everyone but I did want to put it out there just in case someone is having the same problem. Believe me when I tell you it was really bad and quite scary. I will continue smoking for a bit longer and then try to quit again with a patch or something like that. I honestly feel like I became more addicted to nicotine with the e-cigs. Please just be aware that this could be a side effect. Pay attention to your body and how much you are vaping. Don't go overboard. It's just as hard to quit e-cigs as it is to quit regular ones.