When you put nicotine into the body, you create a chemical disturbance and a dependency at nicotine receptor sites.
This disturbance sends increased messages to the brain much like a radio signal. When the nicotine in the bloodstream gets too low, the signal gets interrupted and you can't think straight. Your station isn't coming in loud and clear. You get lightheaded and irritable and have a craving for a cigarette, simply to feel normal.
We use a combination of medications that are non addictive. They bind to the nicotine receptor sites and completely satisfy the body's appetite for nicotine. When you block these receptor sites you also block urges and cravings to smoke and you eliminate all of the unpleasant withdrawal symptoms.