If you experience any negative reaction to the use of e-Liquids then cease using that liquid immediately. There are three ingredients in e-Liquid that may cause a reaction in a very small number of people. The vast majority of people will experience no allergic issue with e-Liquid.
What reactions can people have to e-Liquid?
Allergic reactions to e-Liquid are typically mild.
Propylene glycol is always the first ingredient people blame for a reaction to e-Liquid. The truth is it is VERY unlikely you are allergic to propylene glycol. Also, given the prolific use of propylene glycol in medication and food, it is unlikely you would be unaware that you had such an allergy. That propylene glycol has a chemical sounding name is the more likely reason for its unfairly being blamed first.
That said there are a VERY small number of people who are genuinely allergic to propylene glycol. Switching to a high vegetable glycerine blend may help.
The nicotine used in e-Liquid is in a different form to that found in cigarettes – liquid nicotine.
If you have a reaction to nicotine consider decreasing the nicotine content of your e-Liquid or consider trying zero nicotine products.
This is the most likely cause of any allergic reaction. Different flavourings contain wildly different ingredients. The compounds that make tobacco e-Juice taste like tobacco for example are unlikely to have much in common with those in banana flavouring. If you suspect you are allergic to an ingredient in a certain flavouring then cease using that flavour immediately and switch to another. Trialling different flavours should help you determine which flavours are innapropriate for your particular allergy but it should be safe to assume that similar flavours will contain similar ingredients. Orange and mango or tobacco and cigar could be considered to be made up on similar flavouring.
Giving up smoking
One often overlooked cause of symptoms blamed on e-Liquid is the changes your body goes through if you have coincidentally just given up smoking.
If you have recently stopped smoking information on the symptoms that this can cause can be found online or by consultation with your doctor.