Both low and high fevers are a systemic response of the body to disease-causing factors. A high fever is often defined as an axillary temperature of 39.1°C to 41°C; a low fever, also known as hypothermia, is generally defined as a body temperature that is above normal but below 38°C. In terms of Chinese medicine, colds are divided into wind-heat colds and wind-cold colds. The wind-cold cold is mainly caused by the external wind-cold, and the patient may have no fever or low fever, accompanied by clear runny nose, cough, cold, and little sweating. In contrast, wind-heat colds are mainly caused by external wind-heat, and patients may have high fever, sore throat, runny nose, heavy fever and mild chills. In western medicine, high fever is common in some viral infections such as influenza. And low fever is common in some mycoplasma pneumoniae, chlamydia infection, tuberculosis infection, rheumatic immunity, infectious disease, tumor, etc. There are also some diseases such as lung infections and urinary tract infections, which can also present with low fever before developing into high fever. In summary, there is no particularly strict distinction between low fever and high fever, as many diseases are inherently interconnected. As the disease progresses, it is possible for the patient to change from a low fever to a high fever. Therefore, when a patient develops a fever, it is important to go to the hospital for a timely examination to clarify the cause or pathogen causing the fever.