The question of whether a sauna can help fight a COVID-19 infection is common, often stemming from the belief that high heat can inactivate viruses. Direct clinical research on sauna use during an active COVID-19 infection is limited. The practice carries distinct risks and benefits that must be carefully considered, separating the virus-killing temperature required in a laboratory setting from the temporary physiological changes a sauna safely induces in the human body.
Sauna Heat and Viral Biology
The SARS-CoV-2 virus is sensitive to heat and can be inactivated at high temperatures outside the body. Laboratory studies demonstrate that inactivation requires exposure to temperatures of at least \(56^\circ\text{C}\) for about 30 minutes, or \(80^\circ\text{C}\) for one minute. These temperatures are necessary to denature the viral proteins and render the particle non-infectious.
A sauna session only raises the body’s internal core temperature slightly, typically inducing a mild, temporary fever of around \(38.5^\circ\text{C}\). This modest increase is a safe immune response, but it is far below the heat needed to destroy the virus circulating throughout the body. Attempting to raise the core temperature high enough to inactivate the virus internally would result in dangerous hyperthermia and severe organ damage. Therefore, a sauna cannot function as an internal viral sterilizer.
Effect on Common COVID-19 Symptoms
While a sauna does not cure the infection, the heat and humidity can provide temporary relief from certain respiratory symptoms. The warm air acts as a bronchodilator, relaxing the smooth muscles lining the airways and making breathing feel easier. This effect can temporarily reduce feelings of chest tightness or shortness of breath associated with congestion.
The heat also promotes vasodilation, increasing blood flow to the mucous membranes of the respiratory passages. This increased circulation aids mucociliary clearance, helping to thin and loosen accumulated mucus in the sinuses and throat. The warmth can also help soothe mild muscle aches by improving circulation. However, this symptomatic relief is short-lived and should not be mistaken for a reduction in the overall severity or duration of the illness.
Health Risks During Acute Illness
Using a sauna while acutely ill introduces several significant physiological risks. Dehydration is a major concern, as the body is already prone to fluid loss from fever, reduced appetite, and increased mucus production. The intense sweating caused by a sauna rapidly accelerates fluid and electrolyte loss, which can lead to dizziness, severe fatigue, and impaired immune cell function.
The cardiovascular system is placed under considerable strain when a person with an active infection enters a sauna. The body is already working hard to regulate temperature and fight the virus, which naturally increases the heart rate. The heat forces peripheral blood vessels to dilate dramatically to dissipate heat, causing a drop in blood pressure. The heart must then pump significantly faster to maintain adequate blood flow, which can be dangerous for a system already compromised by systemic inflammation or an elevated heart rate.
Medical Guidance and Precautions
Medical professionals generally advise against using a sauna while experiencing acute symptoms of any viral illness, particularly if a fever is present. The combination of fever and external heat greatly compounds the risk of overheating and severe dehydration. If symptoms are mild and there is no fever, a short, low-temperature session may be considered for temporary congestion relief, but hydration must be maintained.
For public health reasons, it is irresponsible to use a shared sauna facility while contagious, as the enclosed, warm environment can promote the transmission of airborne viruses. After recovery, individuals should consult a doctor before resuming sauna use if they experienced cardiac symptoms or have lingering issues like severe fatigue or chest pain. Rest and hydration remain the most reliable strategies for recovery during acute viral illness.