The following adverse reactions may occur in the early stage of smoking cessation: 1. symptoms related to the central nervous system, such as dizziness, headache, inability to concentrate, insomnia, dreaminess, and even irritability, etc. 2. symptoms related to the digestive system, such as dry mouth, thirst, and strong appetite, etc. 3. symptoms related to the respiratory system, such as coughing, coughing up a lot of phlegm, sore throat, and even difficulty in breathing, etc. 4. Other symptoms include panic attacks, chest tightness, easy fatigue and other symptoms. For the initial period of smoking cessation, patients should actively treat the symptoms, and the symptoms will be reduced or disappear after 45 days or more.