Fever with fluctuating temperatures is called wavy fever, also known as flaccid fever, and is a type of infection fever in the body, which is often caused by a mixture of bacterial and viral infections. In this case, the body produces immune complexes to expel the invading bacteria and viruses, pathogenic microorganisms such as mycoplasma and chlamydia from the body. At this time, the body produces antibodies, and while the antibodies, including antigens, expel them, the body’s temperature drops once and for all. However, when the pathogenic microorganisms re-infect the body, an immune response is generated, and the body temperature rises and activates the neurons in the hypothalamus of the body, causing the central neurons at the point of temperature regulation to move up, so that the fever causes the body temperature to go up and down.