You should not smoke when you have a cold. As colds are a type of respiratory infection, smoking can directly irritate the respiratory system, including the mouth, throat, and nasal mucosa, worsening the condition and triggering coughing and sore throat. This is detrimental to both recovery from the illness and overall health, therefore, smoking should be avoided during a cold. During a cold, it is also advisable to eat a light diet, avoid meat, and consume more fresh vegetables, fruits, and whole grains, drink plenty of water, and avoid staying up late. Generally, recovery will gradually occur within three to seven days. If there is a secondary bacterial infection, antimicrobial medication may also be necessary for treatment.