A fever is the body’s natural response to infection, functioning to create an environment where pathogens struggle to survive. When a fever causes discomfort, the goal of bathing is to provide relief and encourage a slight, gradual temperature reduction. Neither very hot nor very cold water is recommended for managing a fever. Both extreme temperatures can trigger counterproductive physiological responses that may worsen illness or elevate the core body temperature.
Why Extreme Cold Is Harmful
Using ice-cold water, such as a cold shower or ice bath, is counterintuitive and potentially harmful when a person has a fever. Sudden exposure to extreme cold triggers vasoconstriction, causing blood vessels near the skin to rapidly narrow. This narrowing is the body’s attempt to conserve heat by diverting warm blood toward the core.
This response traps heat inside the body, making it harder for the core temperature to drop. The shock of the cold can also immediately cause the shivering reflex, which generates heat through muscle activity. Shivering can paradoxically increase the body’s metabolic heat production by up to 400%, temporarily raising the core temperature and increasing discomfort.
The Risks of Using Hot Water
Taking a hot bath or shower when feverish carries risks related to thermal stress and circulation. Hot water causes vasodilation, the widening of blood vessels throughout the body. This can lead to a rapid increase in the skin’s surface temperature and a subsequent spike in the core body temperature, especially if the fever is already high.
This circulatory stress increases the rate of sweating, which is the body’s natural cooling mechanism. However, excessive sweating induced by hot water can lead to further dehydration, a common concern during a fever. Hot, steamy environments can also cause lightheadedness or dizziness, increasing the risk of falls if the person is already weak.
The Recommended Tepid Bathing Technique
The most effective and safest method for physical cooling is using lukewarm, or tepid, water. Tepid water feels neutral or slightly cool to the touch, generally falling in the range of 85–95°F (29.5–35°C). This temperature promotes cooling without triggering the adverse effects of vasoconstriction or shivering.
The cooling effect relies on evaporation, a highly efficient process where the body’s heat turns the water on the skin into vapor. A sponge bath is often preferred over a shower because it allows for a more controlled application while minimizing effort for the patient.
During a tepid sponge bath, focus application on areas where large blood vessels are close to the surface, such as the armpits and the groin. Apply the water gently with a soft cloth for about 15 to 20 minutes, allowing the water to evaporate naturally rather than rubbing the skin dry immediately. Stop the sponging immediately if the person begins to shiver, as this indicates the water is too cool and the body is entering the counterproductive heat-generating phase.
Warning Signs and When to Call a Doctor
Bathing is a comfort measure and a temporary aid for reducing discomfort, not a substitute for medical treatment or fever-reducing medication. It is important to monitor the patient for signs that require professional medical attention.
For adults, a sustained fever spiking at 103°F (39.4°C) or higher warrants a call to a healthcare provider. Seek immediate medical evaluation if the fever is accompanied by severe symptoms like persistent confusion, a stiff neck, a severe headache, difficulty breathing, or a rash. An inability to keep fluids down due to vomiting is another serious sign that requires medical attention to prevent severe dehydration.