A cold is an infection of the upper respiratory tract, including the nose, throat and pharynx, caused by a cold virus, or bacteria. Infections such as bacteria and viruses cause the body tissues to produce inflammatory factors, which stimulate the thermoregulatory center and cause an upward shift in the thermoregulatory point. This leads to an increase in body temperature, which reduces heat dissipation and increases heat production, resulting in fever. If a temperature greater than 38.5°C occurs or if the fever persists, the patient can be seen in the hospital.