I couldn't tell for sure from your post whether you were using any of your own extracts in the doublers. Is it possible that it's something from the extracts or doublers rather than the nicotine that your're reacting to?
CES,
I am pretty sure it's not the doublers. I've used the same nicotine liquid with some natural tobacco extracts and i got the same physical symptoms. I've also mixed it with concentrates from other vendors - same effect.
I am fairly certain it is the nico liquid.
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