There are a variety of symptoms caused by nicotine withdrawal, including nausea, headaches, irritability, low heart rate, low blood pressure, anxiety, nicotine cravings and depression. Some may experience constipation, diarrhea and fatigue, according to WebMD.
Nicotine withdrawal is caused by the cessation of the use of tobacco or other nicotine products. Low basal dopamine levels and low brain activity are early effects of nicotine withdrawal. During the beginning of withdrawal, the body goes into a hypo-functional state as symptoms of withdrawal begin to manifest, according to Wikipedia. Over time, persons in withdrawal from nicotine may experience weight gain, frustration and restlessness. Depersonalization, a dissociative state where a person feels as if he is watching himself and has no control, is also a symptom of nicotine withdrawal.
Nicotine withdrawal only occurs when nicotine dependant persons cease their use of nicotine containing products. As an addictive substance, quitting nicotine produces withdrawal symptoms much like any other physically and psychologically addictive substance. Nicotine use causes both psychological and physical addiction, thus symptoms of withdrawal may be both psychological and physiological. Examples of psychological withdrawal symptoms include the irritability, depression and anxiety associated with withdrawal. Examples of physiological symptoms include headaches, diarrhea, constipation, fatigue and nausea, states the New York Times.