Deadcat2, I'm going to second that...unless a person is drawing directly into lungs (some call that 'French' inhale, don't know??) if the Proylene Glycol can be very much more drying than Vegetable Glycerin based-eliquid....I used PG for two months before I developed such an aversion to it, not just a few puffs of it gives me terrrific sore throat, lungs burning and painful, and I feel like I'm being strangled. It's a no-go for me. Vg very much more comfortable, no problems with it at all....but not knowing what nic density she's using, it could just be too much of a hit for her, or what flavorings may be irritating...would be unlikely to have such a coughing problem right out of the box. Actually, most nicotine from vaping is absorbed in the mouth nose and throat. The nic isn't carried and absorbed in the lungs via vapor very well, it's just not a fine enough particulate for that. That's why we don't get an instant nic hit from vaping, takes a few minutes to absorb through mucous membranes/ 10 minutes or so to feel a real impact from nicotine.