A sauna is a small room designed to heat the body using dry heat (like hot stones in a traditional Finnish sauna) or wet heat (a steam room). Individuals feeling unwell might be tempted to use this heat exposure to “sweat out” an illness. Health professionals generally advise caution when considering a sauna while actively fighting an infection. The potential risks often outweigh temporary relief, making it important to understand the physiological demands heat therapy places on an already stressed system.
The Core Safety Concern: Fever and Dehydration
The body’s natural response to infection is often a fever, raising the internal temperature to create an inhospitable environment for pathogens. Introducing external heat from a sauna when a fever is present forces the body to work harder to regulate its core temperature, increasing the risk of dangerous hyperthermia or heatstroke. This thermal stress strains the cardiovascular system, causing the heart rate to increase as it pumps blood to the skin for cooling.
Dehydration poses an equally serious risk because illness frequently causes fluid loss through vomiting, diarrhea, or increased perspiration. A sauna exacerbates this fluid deficit through intense sweating, leading to a rapid drop in body water. This fluid loss can quickly cause dizziness, lightheadedness, and potentially dangerous electrolyte imbalances or circulatory complications. Prioritizing rest and hydration is important during illness, and a sauna actively works against this recovery strategy.
Impact on Common Cold Symptoms
For a mild cold, characterized by a runny nose and slight congestion without a fever, the effects of a sauna are often anecdotal. The hot, humid air of a steam room can temporarily offer relief from upper respiratory symptoms. This relief is thought to come from the heat helping to thin mucus secretions and potentially ease sinus pressure.
Despite the feeling of short-term improvement, there is limited scientific evidence to confirm that inhaling hot air significantly reduces the severity or duration of a common cold. The temporary clearing of nasal passages does not affect the underlying viral infection or speed up the recovery process. Even with mild symptoms, the heat can still induce lightheadedness or dizziness, a sign that the body is struggling with the thermal load. Any perceived benefit is palliative, not curative, and must be weighed against the risk of worsening dehydration.
When Sauna Use is Strictly Prohibited
Sauna use is contraindicated when the body is battling a systemic infection. This includes illnesses such as influenza, bronchitis, pneumonia, or gastrointestinal viruses that cause vomiting or diarrhea. These conditions place heavy stress on the immune and circulatory systems, and intense heat can worsen symptoms and delay recovery. A fever, which indicates a serious illness, is the most important reason to avoid a sauna.
Medications and Chronic Conditions
Certain medications make sauna use unsafe because they interfere with the body’s ability to regulate heat or blood pressure. Drugs such as diuretics, beta-blockers, and certain antihistamines can impair the sweating mechanism, making the user prone to overheating or heatstroke. Individuals with chronic conditions, including cardiovascular disease, low blood pressure, or impaired coronary circulation, must avoid saunas when sick. The heat-induced increase in heart rate and blood flow can be dangerous.
Guidelines for Mild Symptoms
Even when dealing with only mild symptoms, any session should be limited to 5 to 10 minutes at a lower temperature. Mandatory pre- and post-hydration with water or electrolyte drinks is required. Users must exit immediately if any discomfort is felt.