Nicotine is a substance that is present in cigarettes. Smoking cigarettes is the number one cause of preventable death in the United States. A tolerance to nicotine develops with long term use. Thus, when nicotine exposure is stopped, within a few hours, the user begins to experience withdrawal symptoms. Withdrawal often conjures up feelings of anxiety and a perception of increased stress. These negative feelings coupled with the loss of the reward response makes nicotine highly addictive. Untreated withdrawal has several side effects which can lead to feelings of the following:

• Irritability
• Depression
• Restlessness
• Anxiety
• Difficulty getting along with others
• Difficulty concentrating
• Increased hunger and eating
• Inability to sleep
• Tobacco cravings
• Difficulty sleeping
• Tobacco cravings
• Hedonic dysregulation (or the inability to feel pleasure from activities that use to be enjoyable)

Smoking Cessation

One solution that has been proposed is nicotine replacement therapies.

These are treatments that administer nicotine in ways other than through tobacco products and smoking to reduce the harmful effects of ingesting tobacco products while still addressing the addiction to nicotine. However, because these methods introduce nicotine into the bloodstream more slowly than smoking, most smokers are not satisfied with them. A preferred treatment would be a method of smoking nicotine other than using a cigarette. Another concern with these therapies is that while they help the user quit smoking cigarettes, which contain several harmful chemicals in addition to nicotine; the treatments still provide nicotine, which may have several long-term effects.

While nicotine is not a carcinogen, it may promote tumor progression.