I have heard of more reactions of this type to various brands of VG than to PG.
PG is entirely synthetic and far less likely to cause allergic reactions such as those to certain vegetable compounds, though intolerance is more likely. The grade is important since only pharma grade can be inhaled, others will have higher levels of contaminants, be they innocuous or not.
Both PG and VG are made in 4 grades:
- Industrial grade
- Agricultural grade
- Food grade
- Pharmaceutical grade
Food Grade PG or VG is NOT suitable for inhalation. Only PHARMA grade should be inhaled.
With PG, which is always 'synthetic' (it has no animal or vegetable sources), the only issue is that of contamination, i.e. if you are going to inhale it, you MUST ONLY use the pharma grade. It is the purest grade and the only one suitable for human use by inhalation or injection. Its uses are typically as the excipient in nebulizers for lung transplant patients, asthma inhalers, and the diluent for injectable medicines such as diazepam that are immiscible (don't mix with water).
In the case of glycerine, in the past we tended to prefer VG, vegetable glycerine, because it was often the only decent type available - others came from unsuitable sources or may have contained more contaminants. This is no longer the case and the only glycerine that should be used is pharma grade glycerine, which is usually synthetic.
Glycerine has numerous sources, such as:
- Animal carcases
- Vegetable sources such as palm oil and coconut oil
- Biodiesel manufacture byproduct
- Synthetic production (as used for pharma grade)
As the vegetable sources were preferable to animal source or biodiesel byproduct, people used to advise the use of VG, vegetable glycerine. This acronym is still used but the product advised is certainly no longer the same. Only PHARMA GRADE glycerine should be inhaled, and this is commonly synthetic.
In fact this product is now advised for use in all inhalable medicines in preference to PG. PG is still used for some applications because it is such a powerful bactericide and virucide, so that certain classes of patients would benefit from this choice. It may be combined with glycerine. For long-term use, there has been a move toward use of glycerine as being preferable. For example Dow Chemical manufacture and supply all grades of both these products, and the one they advise for inhalation duty is their synthetic pharma grade glycerine called Optim. See:
OPTIM - The OPTIM Advantage | The Dow Chemical Company
OPTIM - The OPTIM Advantage | The Dow Chemical Company
So for the original poster I would present these points of interest:
1. Change your brand of product immediately you experience any abnormal symptoms. Restriction of breathing is exactly the opposite of what you can expect from using an e-cigarette as opposed to smoking tobacco. All persons who have fully explored all options have found a suitable product that has no implications whatsoever for lung function or any other aspect of health - there is absolutely no need to accept an imperfect solution.
2. It is simply impossible for all individuals to tolerate all products without issue. At present we have to employ trial and error to find the optimal solution, for ourselves. Some individuals will do best on PG, some on VG. With VG in particular there is a very great variation between brands and ONLY pharma grade must be inhaled. In addition, since some pharma grades will come from vegetable sources, if intolerance is experienced then other brands should be tried. There is a product that will suit you.
3. The glycerine used must be pharma grade, and a synthetic type is advised as it is likely to be the purest. Only distilled water should be added, not tap water, to make the glycerine less viscous if necessary.
4. If you cannot find acceptable sources of glycerine-based e-cigarette refill liquids by trial, then obtain a known acceptable brand such as Ecopure from Intellicig UK (which is 100% glycerine based), or the VG-based refills from Decadent Vapours (available in the US from Liberty Flights). We know these use pharma grade glycerine for inhalable medicines.
5. Many individuals can tolerate a wide range of products, but some cannot. As an example we have found a factor-10 difference in the individual tolerance to nicotine: some will find that what is perfect for another person may be up to ten times too strong or too weak for them. Such individual variation in tolerance to consumables means that a degree of experimentation is needed - and this would be true even in a perfect world where only the purest ingredients were used by all vendors. There is absolutely no need to put up with, for example, reduced lung function, since this is the opposite of normal experience - as you can see from the other posts in this thread.
6. Ex-smokers can still develop conditions related to smoking, after some time has elapsed since cessation. You can quit smoking and develop lung cancer some years later. For this reason it is advisable to consult a doctor if any unusual symptoms are experienced.
