Recently, I've been having some weird side effects that seemed directly related to how much I was vaping. I have gotton headaches before from vaping too much, but I started getting a weird, tingly sensation on the side of my head and then one of my legs started to hurt, kinda like a vein throbbing. I started searching the boards, and really didn't find any other symptoms liek the ones I was having, however, someone mentioned it seemed harder for them to recoup after getting stiff. I realized I was having that problem, too. It may not seem like much, but I was a bit alarmed and cancelled an order for some ecig equipment I had just ordered, convinced I just needed to quit the ecigs. The company I had placed the order with was very nice, in fact, they wrote me back after the cancellation with some follow up questions, just out of concern. We went back and forth with that for awhile and I'm glad we did, cuz I think we have it pinned down to PG. I was okay when I was vaping Blu, then I went to Aqua Vapor and they're both 100%VG. But once I started vaping PG mixes, I started having symptoms. Long story, short, I'm gonna give it another go. I really like vaping, and even though I was trying to stop, I kept dipping in it anyway. So I placed a new order with the company that helped me- thank goodness they have 100% VG and I just wanted other people to know in case someone else experienced the same problems. You know, ecigs are great, but it's such a new thing and we don't know the long term effects of it yet. I really don't think PG is necessarily bad for everyone, but if we can be honest about what's going on when we have problems, we can identify solutions quicker. BTW, that company was EVcigarettes (hope it's not illegal for me to mention their name) adn thy're even running a New Year special right now- celebration2013 for 15% off.