A fever, or elevated body temperature, is the body’s natural response to combat infection or illness. This rise in temperature signals that the immune system is actively fighting a threat. When feeling unwell, a frequent question is whether covering up with a blanket is helpful or harmful. Understanding the biological mechanisms driving the fever is necessary to make the best decision for comfort and safety.
The Science Behind Fever Chills
The sensation of coldness, or chills, experienced during a fever can be confusing because the body temperature is high. This paradoxical feeling occurs because the brain’s temperature-regulating center, the hypothalamus, intentionally raises the body’s thermal set point. Immune signaling molecules, called pyrogens, trigger the hypothalamus to reset this target temperature higher than the normal range of around 98.6°F (37°C).
When the hypothalamus raises the set point, the current body temperature is sensed as too low relative to this new target. To close this temperature gap, the body initiates mechanisms to generate and conserve heat. Blood vessels near the skin constrict, which reduces heat loss from the body’s surface and causes the skin to feel cool. Shivering is also triggered, which is rapid muscle contraction designed to produce heat.
These internal actions, combined with the subjective feeling of coldness, lead to the chills and the natural inclination to seek warmth, such as covering up. The body is working to reach the new, higher temperature mandated by the hypothalamus.
Rising Versus Breaking Fever
The decision to use a blanket depends entirely on the current stage of the fever, characterized by two distinct phases.
Rising Phase
During the rising phase, the body actively generates heat to meet the elevated thermal set point, resulting in chills and a feeling of cold. In this phase, a light covering, such as a sheet or a thin blanket, can be used for comfort and to alleviate the discomfort of shivering.
However, avoid heavy blankets or excessive layers of clothing that could trap too much heat. Overheating the body with thick coverings can interfere with temperature control and may cause the core temperature to rise to potentially unsafe levels. This risk is particularly concerning for young children or those with underlying health conditions.
Breaking Phase
The breaking phase signals that the fever is resolving and the hypothalamus has reset the thermal set point back to normal. The body must now shed the excess heat it accumulated, which it does primarily through vasodilation and sweating. The skin feels warm, and the person often sweats profusely as the body attempts to cool down via evaporation.
During this phase, any blankets or heavy clothing should be removed immediately to allow heat to dissipate effectively. Wearing light, breathable clothing is advisable to permit proper airflow and facilitate the cooling effect of the sweat. Continuing to use heavy coverings during the breaking phase counteracts the body’s natural cooling process and can prolong discomfort.
Essential Practices for Fever Management
Beyond managing blankets and clothing, several other actions support the body during a fever. Maintaining adequate fluid intake is a primary concern because fever and associated sweating can quickly lead to dehydration. Adults should aim to consume plenty of water or clear broth, with electrolyte solutions offering an additional benefit to replace lost minerals.
Medications designed to reduce fever, known as antipyretics, work by interfering with the chemical signals that raise the thermal set point in the hypothalamus. These over-the-counter options, such as acetaminophen or ibuprofen, are recommended to promote comfort rather than solely to reduce the temperature. Follow dosage instructions carefully and avoid alternating medications unless specifically advised by a healthcare provider.
Monitoring the fever and associated symptoms is also important for home management. Medical attention is warranted for any fever that persists for more than a few days or for temperatures that are 103°F (39.4°C) or higher in adults. Seek professional care immediately if a fever is accompanied by symptoms like difficulty breathing, confusion, a stiff neck, or persistent vomiting. Fevers in infants under three months of age should always be evaluated by a medical professional.