4. Fever and Chills
After the initial symptoms of cramping, pain, nausea, and vomiting appear – the next stop is the development of a fever. When the brain realizes it’s under viral or bacterial attack, it signals the immune system to produce antibodies and white blood cells to attack the invading pathogens.
At the same time, the brain signals the hypothalamus to produce “pyrogens.” Pyrogens are enzymes that increase the temperature set point of the body, driving it higher. As a result, the infected individual develops a fever, and the intensity of the fever depends on the severity of the symptoms.
As the pyrogens increase the temperature, there’s a lag in the amount of time it takes the body to heat up to the new setpoint. This lag leads to the development of chills – it’s a sign that the body is ready to turn up the heat on the disease, and your system is lagging.