This is my experience.
Vaping 100% VG at first made me feel fantastic!
Clear lungs after all those years of smoking - I was ecstatic! (Just ecstatic to finally quit smoking!)
Sense of smell back - wonderful!
Feeling like I could walk up hills and not even pant a little - amazing!
My palpitations and ectopic heartbeats completely disappeared - best thing of all!
Three weeks into it though I developed what seemed to be an allergic reaction. Face flushing, red rash on my face, burning itchy/or numb sensations that seemed to float across my face - very odd feeling.
Finally after one night (four weeks into vaping) of intense all over prickly itchy feelings under my skin I stopped vaping and went back to smoking

and all of the above went away except that the
ectopic heartbeats (or PVC's ) came back with a vengeance.
Now I'm once again four weeks back into fully vaping this time with 100% PG.
Absolutely no face flushing/rashes/burning face. All gone - wonderful!
It's obvious to me that I have an allergy to VG. Strange and unexpected but how else can I explain the reaction?
But this time my chest feels terrible.
Tight and heavy - particularly by the end of the day.
I am breathless with my pulse racing after walking up the stairs inside my house! (Drinking loads of water has helped with the breathlessness though I must admit, but it's not completely gone.)
Now the interesting thing is (especially reading on another recent thread here about PG ) that along with that I have been feeling like I am breathing faster and when I lie in bed at night my pulse is FAR quicker than it should be.
At first I was ready to blame that on anxiety, but I can't be entirely sure.
Along with it all my heart is doing flip flops all over the place once again which is VERY disappointing.
Before any one asks it's not nicotine overdose. I'm vaping 12 mg and not chain vaping by any means.
The other day I decided to try, out of curiosity, to vape a 50/50 mix of PG/VG
Almost IMMEDIATELY my chest felt SO much better - clearer. In fact it made me feel 100% better!
That was, until late in the afternoon suddenly one side of my face started getting that familiar burning/flushed feeling.
Damn!
The thing is.... PG may very well be used in asthma inhalers and be deemed as being safe but realistically how many asthmatics are sucking on their inhalers constantly ALL DAY?
Maybe it's not the greatest thing - for everybody?
I'm in a quandary here. I really don't feel very "healthy" vaping at the moment.
I really DO want to be able to vape though and I'm willing to accept that there may be risks. Logically I feel like it's far better to vape than smoke and for me there is no other choice. If I don't succeed at vaping I know I will go back to smoking.
But when you feel worse vaping than what you did smoking it's upsetting and disheartening.
I think for those who are experiencing nothing but positive results from vaping it's hard to understand the concern (and sometimes paranoia) from those who ARE experiencing negative results.
Shortness of breath is a very scary thing and not surprising that it evokes feelings of unease when in happens in conjunction with this new thing in our lives called vaping.
I'm going to once again try a combination of VG and PG today.
I'll go 30% VG 70% PG and see what happens. I'm really just getting desperate I suppose because logically I know the VG doesn't agree with me.