Withdrawal is the body’s reaction to not having the nicotine it had become accustomed to. Withdrawal is most common and intense in cigarette smokers and intermediate in smokeless and e-cigarette users. The symptoms of nicotine withdrawal usually appear 2–3 hours after last intake of nicotine and peak in 2–3 days. In a minority of smokers, cravings may last for years. Nicotine withdrawal causes few physical signs and is not life-threatening but associated cravings can be as severe as withdrawal from other drugs. After the initial withdrawal period, anxiety, depression, and quality of life generally improve such that former smokers are better off than continuing smoking. Causes
Various causes have been proposed to explain the causes of nicotine withdrawal. Nicotine binds to nicotinic receptors in the brain that, in turn, cause an increase in dopamine. Dopamine is the major chemical that stimulates reward centers in the brain. The brain recruits an opposing force to dampen the effects of nicotine and this causes tolerance (the reduction in the effect of nicotine). The onset of this opposing force and the fact that the brain becomes used to and dependent on nicotine to function normally is known as physical dependence. When nicotine intake is decreased, the brains opposing force is now unopposed and this causes withdrawal symptoms. It also appears that opiate, serotonergic, glutamic, cannabinoid, and corticotrophin receptors may play a role in nicotine withdrawal. In addition, smoking becomes conditioned to environmental cues that can then prompt withdrawal symptoms.
Support for the joints is especially important during sports, and some recommend that contact sports should be avoided by those who have very loose joints. References


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