The choice of a substitute depends on what will achieve the same effects without having any appreciable risk. These may include headache, lightheadedness, nausea, diarrhea, and chest pains. Psychological symptoms, such as anxiety, short-term depression, and inability to concentrate, may also appear. The main psychological symptom is increased irritability. Yet, there is no evidence that quitting smoking leads to physical violence.
Some people seem to lose all their energy and drive, wanting only to sleep.
Others react in exactly the opposite way, becoming so over-energized they can't find enough activity to burn off their excess energy. For instance, one woman said she cleaned out all her closets completely and was ready to go next door to start on her neighbour's. Both these extremes, however, eventually level off. The symptoms may be intense for two or three days, but within 10 to 14 days after quitting, most subside. The truth is that after people quit smoking, they have more energy, they generally will need less sleep, and feel better about themselves.