I have read somewhere that some people have an allergic reaction to PG liquid. I don't really know what the symtoms are. I myself mix my own e-liquids and I could never get the taste that I wanted, I would always get a bad chemical aftertaste especially on the exhale, it was terrible, stayed with me all day seemed like. I was mixing 70/30 PG/VG. Then I switched to 20/80 PG/VG and some at 100% vg. Now everything is great,in fact my mixes taste fantastic, the same or better than any supplier I have purchased from(just my opinion). I buy from PA and now mix at 5% and the flavor is amazing. Now I hope I didn't bore you to much! But I was wondering if this is a symptom.