A sauna exposes the body to a short period of elevated thermal stress. People often seek this hoping it will “sweat out” an illness or speed up recovery from a cold. Potential benefits or risks depend heavily on the specific type and severity of the illness a person is experiencing. This requires understanding the body’s response to heat and the practical dangers of using a sauna while unwell.
Physiological Effects of Heat on the Immune System
Short-term exposure to high heat causes a temporary, controlled rise in the body’s core temperature, a process known as induced hyperthermia. This mimics a mild fever, which is the body’s natural defense mechanism against invading pathogens. The elevated temperature is theorized to create an environment less favorable for the replication of some viruses and bacteria.
The heat also triggers systemic vasodilation, causing blood vessels to widen and significantly increasing circulation throughout the body. Enhanced blood flow acts like a superhighway for the immune system, potentially accelerating the movement of white blood cells to sites of infection and inflammation. Studies show that a single sauna session can increase the number of circulating white blood cells.
Furthermore, the thermal stress prompts cells to produce specialized molecules called Heat Shock Proteins (HSPs). These proteins help stabilize existing cell structures and repair those damaged by stress or infection. HSPs are also believed to play a direct role in regulating the innate immune response. This temporary, controlled activation of the body’s internal defense systems is the primary mechanism behind any potential immune support from sauna use.
Managing Common Illness Symptoms
For an individual suffering from a mild common cold without a fever, a sauna may offer temporary relief from specific uncomfortable symptoms. The warmth itself helps to relax tense muscles, which can provide a welcome break from the generalized body aches, or myalgia, that often accompany an infection.
In the case of a steam room, the high humidity and moist heat are particularly effective at addressing respiratory discomfort. Inhaling the warm, humid air helps to moisturize the nasal passages and throat. The moisture works to thin the mucus blocking the sinuses and chest, making it easier to breathe and temporarily clearing congestion.
Beyond the physical effects, the quiet, warm environment of a sauna can offer temporary psychological benefits by promoting relaxation. Illness often increases mental stress, and the soothing heat can help reduce that tension. This temporary stress reduction can support the body’s recovery process by creating a more restful state.
Essential Safety Warnings and Contraindications
While the potential for minor symptom relief exists, using a sauna when sick carries risks. The most dangerous contraindication is the presence of a fever, typically defined as a temperature over 100.4°F (38°C). Introducing external heat from a sauna to an already elevated internal temperature can overload the body’s thermoregulatory system, dramatically increasing the risk of overheating or heatstroke.
Illness frequently involves fluid loss, which pre-disposes the body to dehydration. The profuse sweating induced by a sauna severely exacerbates this fluid loss, which can worsen symptoms like weakness, dizziness, and headache. Dehydration compromises the body’s ability to regulate its own temperature, so it is imperative to skip the sauna if you are already struggling to keep fluids down.
Individuals with pre-existing cardiovascular issues should exercise extreme caution, as the heat stress places a greater demand on the heart by elevating the heart rate and changing blood flow dynamics. Some over-the-counter and prescription medications, including certain decongestants and antibiotics, can interfere with the body’s ability to sweat or regulate heat, increasing the danger of overheating. If a person is feeling dizzy, weak, or lightheaded, they should avoid the sauna entirely and consult a healthcare provider.