A fever is a temporary increase in your body’s temperature, indicating your body is fighting an illness. Despite rising body temperature, feeling cold or shivering is common. This counterintuitive sensation is explained by the body’s temperature control system.
How the Body Regulates Temperature
The human body maintains a stable core temperature, typically around 98.6 degrees Fahrenheit (37 degrees Celsius). The hypothalamus, a small brain region, acts as the body’s internal thermostat, constantly monitoring and adjusting temperature to keep it within a narrow, healthy range.
When the body’s temperature deviates from this established set point, the hypothalamus initiates various mechanisms to bring it back into balance. If the body becomes too warm, it may increase blood flow to the skin through a process called vasodilation, allowing heat to escape, and activate sweat glands to cool the surface through evaporation. Conversely, to generate or conserve heat when feeling too cold, the body may trigger shivering, which involves rapid muscle contractions, and vasoconstriction, where blood vessels near the skin surface narrow to reduce heat loss.
The Chill Sensation Explained
Feeling cold during a fever stems from the hypothalamus, the body’s thermostat, being temporarily reset to a higher temperature. When infection or inflammation occurs, the immune system releases pyrogens. These pyrogens signal the hypothalamus to raise the body’s temperature set point.
For instance, if the normal set point is 98.6°F, pyrogens might instruct the hypothalamus to aim for 102°F. Your actual body temperature, still at 98.6°F or just beginning to rise, is then perceived as too low relative to this new, higher set point. This discrepancy tricks the body into thinking it is cold.
To bridge the gap between the current actual temperature and the new, elevated set point, the body initiates warming mechanisms. These include shivering, where involuntary muscle contractions rapidly generate heat, and widespread vasoconstriction, which reduces blood flow to the extremities and skin. Vasoconstriction explains why skin may appear pale or feel cool to the touch during a chill, as the body redirects warm blood to the core.
Coping with Fever Chills
While fever chills can be uncomfortable, they are a natural part of the body’s response to infection. The primary goal during this phase is to manage discomfort and support the body’s healing process.
Use light blankets or sheets rather than heavy layers, as excessive bundling can trap heat and make it harder for the fever to break naturally. Staying hydrated is important; drinking plenty of fluids like water, clear broths, or rehydration solutions helps prevent dehydration, which can worsen fever symptoms.
Resting allows the body to conserve energy and focus its resources on fighting the underlying illness. Wearing comfortable, breathable clothing can also contribute to overall comfort.
Monitor symptoms and consider seeking medical attention if the fever becomes very high, causes severe discomfort, or persists. Consult a healthcare provider if you have underlying health conditions or specific concerns.