I have been using the e cigs w/pg for about a month and i had severe lung inflamation I have never felt so bad in my life I was coughing had chest pain and could not breath. I would never use it again I have quit smoking and I really liked it it did help me but the end result was horrible.
I bought my first 3-cig earlier this year, it was an Anytime E-Cig, I used it quite a bit and all was fine for awhile, then one evening I started getting severe chest pain which also radiated to my back, I don't actually know if it was from the e-cig or not but it reoccurred a few times, eventually I went to the doctor about it and he didn't think it was anything serious.
I stopped using the e-cig and haven't had this problem occur over the past few months, i'm not certain it was caused by it but it seems possible.
Now it could have been something in the e-cig causing it or it could have been just over use, also where you drag a bit longer and harder it could have just been stressing the lungs, or the chest wall muscles, i'm not sure.
Anyway, since stopping the e-cig I went back to regular cigs now and then, but have decided to try again, I got a greensmoke e-cig now and so far i've not had any problems, but im making sure not to overdo it, lets be honest we know they are safer than real cigs but we dont know that they are totally safe yet, its too soon so I think use in moderation is the key, especially if you do have any side effects.