I'm curious that about half of e-cigarette users feel that they must give up nicotine. Why? What ill effects have been caused by the nicotine itself, as a separate thing from the ill effects of inhaling smoke?
Here's a discussion of nicotine effects
Casaa.org - Harm Reduction
The only negative effects of nicotine per se that I have been able to find were possible premature delivery. And even that effect might not be due to nicotine alone, but rather to cigarette smoke. The latest guidelines tell doctors that if they have a pregnant patient who cannot give up smoking, that switching her to NRT will reduce the health risks.
In my case, when I give up nicotine I become very very ill. Depression runs in my family, often accompanied by anxiety. Nicotine helps to relieve symptoms of mood impairments. I have been diagnosed with Attention Deficit Disorder. My ability to concentrate and pay attention goes way down when my nicotine levels get low. Parkinson's disease is accompanied by a build-up in the brain of "Lewy Bodies." Lewy Body Dementia (LBD) resembles Alzheimers Disease (AD), but it is accompanied by Parkinson-like stiffness, impaired gait, balance problems, and increasing immobility in the end stages. Hallucinations and delusions are more common with LBD than with AD, but treating with antipsychotics makes the situation worse instead of better. After watching my mother become increasingly immobilized and to have conversations with her become more and more bizzare ("There's a demon living in my curio cabinet"), I have vowed that I will NEVER give up nicotine.
Unlike the other two addictive drugs to which the Surgeon General has compared nicotine, nicotine does not impair thinking, alertness, or concentration. It enhances all these abilities. I'll bet there isn't a state in the union that has a law against Driving Under the Infuence of Nicotine.
Actually, the last time that I became totally abstinent from nicotine (about 23 years ago) I was so confused and inattentive that when driving a car, it didn't feel a lot different from trying to drive a car while drunk. After two near misses, I grounded myself until I resumed using nicotine.