Nicotine is the active agent within tobacco products and is a stimulant.
Within the brain, nicotine increases attention and concentration. Some researchers are investigating the effects of nicotine on memory, as it stimulates acetylcholine, which is related to memory.
Users also report that nicotine has a calming, anti-anxiety effect. It is unclear if this is due to the effect of the nicotine or if the rituals associated with tobacco use have the primary calming effect.
Use of tobacco products is associated with decreased appetite. This may be related to the stimulant effect of nicotine, to the deadening of the taste buds due to tobacco, or the oral ritual of tobacco use.