This medication can help you quit smoking by replacing the nicotine in cigarettes. The nicotine in tobacco is an important part of cigarette addiction. When you stop smoking, your nicotine levels drop quickly. This drop can cause withdrawal symptoms such as craving tobacco, nervousness, irritability, headache, weight gain, and difficulty concentrating. Stopping smoking is hard and your chance of success is best when you are ready and have made a commitment to quit. Nicotine replacement products are part of a total stop-smoking program that includes behavior change, counseling, and support. Smoking causes lung disease, cancer, and heart disease. Stopping smoking is one of the most important things you can do to improve your health and live longer.