More people seem to have issues with cinnamon than just about anything else. Not heard anything bad about vanilla though.
If you aren't experiencing any problems then you should be OK - but if you feel anything at all out of order, then move to another liquid / another supplier. This stuff either tells you it's wrong for you fairly soon or not at all, or so it seems to me. Dark colors in the flavoring are another similar thing - as soon as you hit it you know that one's no good for you personally (it might be OK for someone else). People are different, some can smoke 50 cigs a day and seem to have no issues, others get bronchitis if they smoke 8 a day. People are different, what applies to one doesn't apply to another.
You might also consider whether or not it is wise to
vape anything and everything. Some people might say it could be better to keep to simple flavors. There is a school of thought that says some of these things just shouldn't be vaped. Up to you.
