Most long-term smokers experience shortness of breath after quitting, which is clinically called withdrawal reaction, or nicotine withdrawal syndrome, a special syndrome after losing tobacco intake. When smoking, nicotine enters the human bloodstream, stimulating the brain to produce certain hormones, making the body appear euphoric and other pleasurable reactions, relieving the body of tension, anxiety, etc. In the long run, the brain nervous system will become dependent on nicotine. When quitting smoking, the body suddenly loses nicotine intake, resulting in endocrine and circulatory system disorders, irritability, panic, shortness of breath, agitation, inability to concentrate, insomnia and other manifestations, also known as nicotine withdrawal syndrome. It usually appears 24h after quitting smoking, peaks in about 3 days, and gradually subsides in about 1 week. If the symptoms of withdrawal syndrome are more severe, symptomatic measures such as oxygen, tai chi, yoga, and psychological counseling can be given to relieve the symptoms of shortness of breath.