In all seriousness though there are a few side effects.
Anytime you inhale anything other than clean air there can be issues. This also includes smog and many things other than vaping, but vaping is inhaling something not typical for your body to breathe. If you have COPD, Emphysema, or Asthma you can have serous issues. My wife cannot inhale many of the flavor blends without having to use her inhaler or nebulizer.
I have asthma, had had it for 30 yrs, and after 3 1/2 wks of vaping, the only side effect I have is the near-total absence of lung mucus -- now it's in my throat, which is probably from the vapor. And yes I do sometimes have to use my inhaler, but then, that's always going to be necessary when you have bronchial asthma. I do use it a lot less frequently, and I don't wake up drowning in my own mucus and grabbing for the inhaler before I'm even out of bed.
There are people who can have a sensitivity to Polypropylene Glycol. Sometimes they can have an outright allergy to it. This is not very common but it can happen and you have to buy pure VG Ejuice. Keep in mind that the flavors used even in pure VG blends could have PG in them. Generally not enough to react with a person though. But everyone is different.
As far as I know, it's not polypropylene glycol, it's just propylene glycol. And the main thing is that it can dry you out, though I suppose some may have allergies to it. Pure VG is far too heavy for these asthmatic lungs, and makes me feel like I have a hairball in my chest I can't get rid of it.
The next is not a side effect of vaping as much as it is nicotine that is in ejuice. Nicotine has been known to constrict blood vessels and can cause vascular damage and even the loss of limbs in extreme cases. Keep in mind that despite many people say smoking relaxes them, Nicotine is a stimulant like caffeine.. So use can cause sleeplessness, anxiety, agitation, and these can be amplified when someone is undergoing withdrawals.
This also increases blood pressure so if you have heart conditions, diabetes, or prone to strokes, Using nicotine would be a bad idea overall... In some cases people have became ill form Nicotine overdose because their vapes taste so dang good!
It relaxes you for the same reason that stimulants calm children with ADHD -- it coordinates neurotransmitters and makes your brain work more effectively. But it can indeed constrict blood vessels, which is why withdrawal causes headaches; when the blood vessels dilate and become engorged, that's much the way migraine headaches work. However too much nicotine can indeed cause overdose, all those stimulant-related effects, but worst of all, nausea/vomiting.
Ejuices that contain diacetyls can cause serious lung issues. Always know whats in your juice!!!!!
Yes you should know what's going into your body in any context, but I think the diacetyl thing is old news that has been beaten to death.
Vaping Pure VG at 0mg Nic, so far has not been proven to cause any issues.
It makes me cough continuously, feeling I have a hairball in my chest, because it is just too heavy for asthmatic lungs. PG is lighter and anyone with asthma should be well accustomed to it, as it's in inhalers and the liquid used in nebulizers.
Andria