If pneumonia is not treated thoroughly, recurrence will usually occur in the near future, with individual differences in the timing of recurrence related to their physical quality and environmental factors. In general, patients should be treated with the appropriate, full course of antibiotics or antivirals depending on their type after the first occurrence of pneumonia. If treatment is not complete, the mucous membrane of the lung may become congested, edematous, and inflammatory reaction with exudation of inflammatory substances, which cannot be fully restored to normal. At this time, if you get cold, stay up late, or are overly tired, this can lead to pathogens being inhaled into the lungs through the respiratory tract and reinfection, leading to a recurrence of pneumonia. However, the specific time of relapse varies, if the health is poor, relapse may occur after 1 week, and some may also occur after 1 month. After a relapse of pneumonia, patients are advised to have their blood tests and chest X-rays checked in a timely manner to further analyze the pathogens and to take the appropriate amount and course of medication. In addition, patients are advised to eat a light diet, avoid spicy and oily foods, and avoid fish, shrimp and other seafood to promote recovery.