Tobacco creates a nicotine dependence that involves physical and psychological factors that make it difficult to stop using tobacco, even if the person wants to quit. Nicotine releases a chemical called dopamine in the same regions of the brain as other addictive drugs. It causes mood-altering changes that make the person temporarily feel good. Inhaled smoke delivers nicotine to the brain within 20 seconds, which makes it very addictive—comparable to opioids, alcohol and cocaine.
When the person stops using tobacco, nicotine levels in the brain drop. This change triggers processes that contribute to the cycle of cravings and urges that maintains addiction. Long-term changes in the brain caused by continued nicotine exposure result in nicotine dependence, and attempts to stop cause withdrawal symptoms that are relieved with renewed tobacco use.
Signs and symptoms of nicotine withdrawal include:
irritability
restlessness
anxiety
insomnia
difficulty concentrating
fatigue