The main reason for chills in hyperthermia is that the pyrogen crosses the blood-brain barrier and acts directly on the body’s thermoregulatory center, causing the temperature to shift upward. The thermoregulatory center, which re-regulates body temperature, sends out impulses and increases the metabolism of the body through pituitary endocrine factors or strengthens the contraction of skeletal muscles through motor nerves, which clinically manifests as chills and increases their heat production. On the other hand, it can also make the skin, blood vessels and erector spinae muscles contract through sympathetic nerves, stopping sweating and reducing heat dissipation. The combined regulation of these two causes the body to produce more heat than it dissipates, thus increasing body temperature and causing hyperthermia. It is usually seen clinically in various acute infections such as bacteria, viruses, rickettsia and parasites, etc.