Saunas, which use dry heat, or steam rooms, which use moist heat, are often viewed as a way to “sweat out” a sickness. The idea that introducing external heat can accelerate recovery is tempting, but the true effect of a sauna depends entirely on the type and severity of the illness. For certain minor symptoms, the heat can provide temporary relief, but for more systemic infections, the practice can pose a significant health risk.
Using a Sauna for Mild Upper Respiratory Symptoms
If symptoms are limited to a runny nose, mild congestion, or a slight cough without any fever or body aches, a short sauna session may offer some temporary comfort. The warm air and increased temperature can help to dilate blood vessels, which improves circulation throughout the body. This boost in blood flow can momentarily ease muscle stiffness that sometimes accompanies the early stages of a cold.
For those using a traditional sauna where water is poured over hot rocks, the resulting steam can act similarly to a humidifier. Inhaling this warm, moist air helps to loosen mucus and clear nasal passages, providing a fleeting sense of easier breathing.
However, even with mild symptoms, sessions must be kept brief, ideally no more than 5 to 10 minutes, and at a moderate temperature. The body is already working to fight the infection, so adding the stress of intense heat requires caution. Immediate and thorough rehydration is necessary after even a short session to compensate for fluid loss from sweating. Ignoring hydration will diminish any potential symptomatic benefit and can impede the body’s recovery process.
Why Saunas Are Dangerous When You Have a Fever
Using a sauna when experiencing a systemic illness—marked by fever, severe body aches, or a stomach virus—is strongly advised against because it introduces significant physiological danger. A fever is the body’s intentional elevation of core temperature, regulated by the hypothalamus in the brain, to create an environment hostile to pathogens. Introducing external heat from a sauna forces the hypothalamus to work harder to manage an even greater thermal load.
This extra thermal stress dramatically increases the risk of hyperthermia, which can overwhelm the body’s natural cooling mechanisms. Adding the strain of a sauna diverts energy away from the healing process, potentially prolonging the illness.
Illness itself often leads to a state of dehydration, and a fever accelerates this fluid loss. The intense sweating induced by a sauna rapidly compounds this issue, making severe dehydration a real and immediate risk. The cardiovascular system is also strained, as both fever and sauna heat increase the heart rate, which can be taxing on an already compromised system. For these reasons, any sign of fever or widespread body discomfort should be an absolute contraindication for sauna use.
Returning to Sauna Use After Illness
It is generally recommended to wait at least 24 to 48 hours after all fever, chills, and severe body aches have completely subsided without the use of fever-reducing medication. This waiting period ensures the body has moved past the most intense phase of the infection and is no longer highly contagious.
When reintroducing heat therapy, start with a gentler approach. This means using a lower temperature setting than normal and limiting the duration to a very short session, perhaps five minutes, to assess tolerance. The body’s energy reserves may still be depleted from fighting the illness, and an overly intense session can lead to fatigue or a relapse of symptoms.
Post-sauna care is especially important during this transition phase, requiring immediate and plentiful hydration with water or electrolyte-rich fluids. While regular sauna use is studied for potential long-term immune benefits and can aid in recovery by improving circulation, it is not a cure for an active, established infection. Easing back into the routine slowly and prioritizing rest will support a full recovery.