Persistent low fever is usually caused by the following reasons: First, from the perspective of Chinese medicine, because the body is too weak, it is easy to be invaded by external wind-cold and wind-heat-damp evil, causing persistent low fever. Second, from the perspective of Western medicine, there are usually several causes: 1. The most common factor is infectious, often due to bacterial infections, viral infections, atypical pathogens and fungal infections that cause persistent low-grade fever. 2. 3. Persistent hypothermia can also occur in endocrine dysfunction, such as hyperthyroidism, and the clinical symptoms described above.