The identification of the main symptoms of cough includes the time, rhythm, nature, and sound of the cough as well as factors related to aggravation. If the cough is more frequent during the day than at night, if the cough is sharp and heavy, or if the throat is itchy, the cough is usually caused by external wind-cold, wind-heat or wind-dryness. If the cough is hoarse and the illness is acute but short-lived, it is due to external wind-cold, wind-heat or wind-dryness; if the illness is slow and long-lived, it is due to yin deficiency or qi deficiency. If the cough is coarse and muddy, it is mostly due to wind-heat or phlegm-heat injury to the fluids. If the cough is worse in the morning and the cough is heavy and muddy, but the phlegm is reduced, it is mostly due to phlegm-dampness or dry-heat cough. If the cough worsens in the afternoon or at dusk, or if there is a single cough at night with a slight shortness of breath, the cough is mostly due to lung dryness and yin deficiency, and if the cough is more violent at night and persists, with little breath or with asthma, it is a deficiency of cold caused by a long cough. If the cough is low and the air is dispelled, it is deficient; if it is loud and strong, it is real; if the cough is aggravated by fatty, sweet or cold food, it is mostly phlegm-damp; if the cough is aggravated by depression and anger, it is due to qi-fire; if the cough is aggravated by exertion or shock, it is mostly phlegm-damp or deficient cold.