West R J, Russell M A
Psychol Med. 1985 Nov;15(4):891-3. doi: 10.1017/s0033291700005134.
A small proportion of smokers who stop smoking with the aid of nicotine chewing gum continue to use the gum for more than a year. This study shows that when these people abstain from nicotine gum use they experience withdrawal symptoms similar to those found during cigarette withdrawal, including increased irritability, difficulty in concentrating and a drop in heart rate.
