Elderly people may have fever in the afternoon due to various reasons such as tuberculosis, autonomic dysfunction, common cold and other diseases. 1. Tuberculosis: Tuberculosis may be caused when the lungs are infected by Mycobacterium tuberculosis, and the typical symptoms of the disease are fever in the afternoon and coughing, etc., and the elderly may have a fever in the afternoon. 2. Autonomic dysfunction: Some elderly people may experience autonomic dysfunction in the afternoon when they are affected by various factors such as living habits and external stimuli. In this case, it can also cause fever in the afternoon. 3. Common cold: when the elderly are in poor physical condition, they may be stimulated by the cold air and cause common cold, which may appear in the afternoon when the condition is serious. 4. Other diseases: Older people suffering from certain malignant diseases such as tumors, or blood system diseases, connective tissue diseases such as systemic lupus erythematosus, may also have a fever in the afternoon. Elderly people who have fever in the afternoon may also have other causes, and it is recommended that they go to the hospital in time to clarify the specific causes of the disease.