By Dr. Tiffany Dubec, DC | High Tech Health Clinical Team

You woke up with that scratchy throat. Maybe a stuffy nose. Your body feels heavy. And you keep staring at your infrared sauna wondering: should I get in there, or is that a terrible idea right now?

It is one of the most common questions I get from sauna owners. People know their infrared sauna helps them feel great when they are healthy. But the moment a cold, flu, or fever shows up, nobody is sure what to do.

Here is the honest answer: sometimes your sauna can genuinely support your recovery. Other times, it can make things worse. The difference comes down to timing, symptoms, and knowing your own body. I want to walk you through the science and the practical guidelines so you can make a smart call next time you are feeling under the weather.

What Happens Inside Your Body During an Infrared Sauna Session

Before we talk about illness, it helps to understand what your infrared sauna is actually doing. When you sit in a far infrared sauna, the infrared light penetrates your skin and raises your core body temperature from the inside. This is different from a traditional sauna, which heats the air around you and relies on convection. Infrared works through radiant heat, warming you directly at much more comfortable air temperatures than a traditional sauna requires.

That rise in core temperature triggers a cascade of responses. Your heart rate increases. Blood vessels dilate. Circulation improves. You start sweating. And your cells produce proteins called heat shock proteins, or HSPs.

These heat shock proteins are a big part of the story. Research published in the Journal of Athletic Training found that just 30 minutes of heat exposure raised HSP72 levels by 49% in healthy adults (1). A separate study showed that six days of deep tissue heat therapy increased HSP70 and HSP90 levels by 45% and 38% respectively, while also improving mitochondrial function (2). HSPs play direct roles in immune function. They activate dendritic cells, stimulate natural killer cells, and help your immune system identify and respond to pathogens more efficiently (3).

Sweating in a TR2 infrared sauna

In plain terms, your infrared sauna creates an artificial mild fever. And your body responds by ramping up many of the same defenses it uses to fight infection. You can learn more about how saunas boost the immune system on our website.

The Research on Sauna Use and Getting Sick Less

The strongest evidence for sauna use and illness is about prevention. Consistent sauna use makes you less likely to get sick in the first place.

A well-known 1990 study published in the Annals of Medicine followed 50 volunteers over six months. Half used a sauna regularly. The other half did not. The sauna group had significantly fewer colds, especially in the last three months of the study when the incidence was roughly cut in half compared to the control group (4). The researchers suggested that the immune changes triggered by heat exposure, including increased immunoglobulin and white blood cell production, likely contributed to the protection.

A much larger and longer study, the Kuopio Ischemic Heart Disease Risk Factor Study from the University of Eastern Finland, tracked over 2,200 middle-aged men for 25 years. Those who used a sauna two to three times per week were 28% less likely to develop pneumonia. Frequent users, four or more times per week, saw a 37% reduced risk. A related analysis found that regular sauna bathing was associated with a 41% lower risk of respiratory diseases overall (5).

A 2023 study in Hyperthermia examined immune markers after a series of Finnish sauna sessions in young men. After ten sessions, researchers saw significant changes in white blood cell subpopulations, natural killer cells, and HSP70 levels. They concluded that repeated sauna bathing, not just a single session, improved the immune response (6).

The takeaway is clear. Regular infrared sauna use builds a stronger immune foundation over time. If you are wondering how long it takes to see benefits from infrared sauna use, many of the immune benefits start appearing within a few weeks of consistent use, with the most meaningful results showing around the three-month mark.

When Your Infrared Sauna Can Help During a Cold

You caught a cold. Your nose is stuffy. Your throat is sore. Maybe your muscles ache a little. But you do not have a fever.

This is actually a reasonable time to use your infrared sauna.

The warmth from a far infrared sauna improves circulation, which means more oxygen and immune cells get delivered throughout your body. Better blood flow also supports detoxification through sweat, helping your body clear metabolic waste while your immune system is working overtime.

The heat can help loosen nasal congestion and relax tight, achy muscles. Your body also releases endorphins and beta-endorphins during sauna sessions (7), which can counter that sluggish, run-down feeling that comes with a cold.

There is also a hormone angle. Chronic stress and elevated cortisol suppress immune function. Research shows that repeated infrared sauna use helps balance cortisol levels (8), which means your immune system can work without fighting against stress hormones at the same time.

Relaxing in a Transcend Infrared Sauna

Practical cold protocol:

At the very first sign of a cold, that tickle in your throat or that heavy-headed feeling, consider a gentle session. Start at a lower temperature, around 100 to 120 degrees Fahrenheit. Keep the session shorter than usual, 15 to 20 minutes. Drink plenty of water before, during, and after. If you feel worse at any point, get out. Rest afterward.

One advantage of having a home infrared sauna is that you avoid exposing others to your germs.

A public sauna or gym sauna should absolutely be off limits when you are contagious.

When You Should Not Use Your Sauna: Fever, Flu, and Beyond

This is the part that matters most. And I need to be direct about it.

If you have a fever, do not use your infrared sauna!!

Period. No exceptions.

A fever means your body has already raised its internal temperature as a defense mechanism. The hypothalamus resets your body’s thermostat upward, triggering an immune response that includes increased white blood cell activity, interferon production, and creating an environment less hospitable to viruses and bacteria (9). The American College of Critical Care Medicine defines fever as a core temperature of 100.9 degrees Fahrenheit or higher (10).

When your body is already running hot, adding more heat from a sauna can overwhelm your thermoregulatory system. The risks are real: dangerous overheating, severe dehydration, dizziness, fainting, and cardiovascular strain. Your heart is already working harder during a fever. Piling on sauna heat is not helpful. It is reckless.

The flu deserves extra caution. Influenza often comes with higher and longer-lasting fevers than a common cold. It also causes more severe fatigue, body aches, and can affect the cardiovascular system. Even if your fever temporarily breaks, your body is still fighting hard. Wait until your fever has been completely gone for at least 24 hours before you even think about a sauna session.

Other times to skip the sauna:

Severe respiratory infections like bronchitis or pneumonia. The extra heat and potential for dehydration can worsen breathing difficulties. Stomach viruses, where dehydration is already a major concern. Any time you feel extremely weak, dizzy, or lightheaded. If you have a chronic heart condition, always check with your physician before using a sauna during any illness.

I know the sauna feels like a comfort tool when you are miserable. I get it. But the sauna will be there when you are ready. Pushing through when your body is already maxed out does not speed recovery. It slows it down.

The Recovery Window: Getting Back to Your Sauna After Illness

Once the worst is behind you, your infrared sauna can be a real asset during recovery.

After your fever has been gone for a full 24 hours, you can start easing back in. Think of it like returning to exercise after being sick. You would not go run a marathon. Same idea here.

Start with a lower temperature and a shorter session. If you normally do 30 minutes at 130 degrees, try 15 minutes at 110 degrees for your first session back. See how your body responds. If you feel good, gradually increase over the next several sessions. Our beginner sauna guide has a good framework for this kind of phased approach.

During the recovery phase, the sauna can help with lingering muscle soreness, improving sleep quality, and giving your immune system continued support through heat shock protein activation. The improved circulation helps deliver nutrients to tissues that are still healing. And the stress reduction benefits are especially valuable when your body is depleted from fighting off an infection.

Hydration matters even more during recovery. Your body has already lost fluids from the illness itself. Replenish electrolytes and minerals, especially magnesium, potassium, and sodium, alongside plenty of water.

Sweating in an infrared sauna

A Note on Sleep and Immunity

One often-overlooked benefit of infrared sauna use during cold and flu season is sleep improvement. Research from Frontiers in Immunology has shown that people sleeping fewer than seven hours per night are nearly three times more likely to catch a cold compared to those getting eight or more hours (11).

Deep sleep is when your body produces cytokines, the proteins that target infection and inflammation. Your body also replenishes immune cells during sleep. Anything that improves sleep quality indirectly strengthens your immune defenses.

Using your infrared sauna in the afternoon or early evening helps your body relax and raises your core temperature. The natural temperature drop that follows cues your body that it is time to sleep, potentially improving both the speed of falling asleep and the depth of your sleep cycles. This is one reason why regular sauna use during the fall and winter months is particularly smart for supporting respiratory health and immune resilience even before illness strikes.

My Basic Advice: A Simple Decision Framework (Keep it Simple!)

**Use your infrared sauna:

Regularly throughout cold and flu season as a preventive strategy. At the first sign of a cold when no fever is present. During recovery, once fever-free for 24 hours, starting with lower temps and shorter sessions.

**Do not use your infrared sauna:

When you have a fever of any kind. During active flu symptoms. With severe respiratory infections. When you are extremely fatigued, dizzy, or dehydrated. If you have an underlying condition, without clearing it with your doctor first.

Your infrared sauna is one of the best wellness tools you can own. But like any tool, it works best when you use it with common sense and respect for what your body is telling you. The research shows that consistent, long-term sauna use builds a stronger, more resilient immune system. Use that knowledge to stay ahead of illness rather than trying to fight through it when you are already down.

Be patient with yourself. Rest when you need to rest. And when you are ready, your sauna will be waiting.

If you have questions about how to use your High Tech Health infrared sauna during cold and flu season, or you want help building a personalized wellness protocol, our clinical team is always here to help. Request a practitioner consultation and we will get you pointed in the right direction.

References

  1. Iguchi M, Littmann AE, Chang SH, et al. Heat stress and cardiovascular, hormonal, and heat shock proteins in humans. Journal of Athletic Training. 2012;47(2):184-190. doi:10.4085/1062-6050-47.2.184
  2. Hafen PS, Preece CN, Sorensen JR, Hancock CR, Hyldahl RD. Repeated exposure to heat stress induces mitochondrial adaptation in human skeletal muscle. Journal of Applied Physiology. 2018;125(6):1447-1455. doi:10.1152/japplphysiol.00383.2018
  3. Patrick RP, Johnson TL. Sauna use as a lifestyle practice to extend healthspan. Experimental Gerontology. 2021;154:111509. doi:10.1016/j.exger.2021.111509
  4. Ernst E, Pecho E, Wirz P, Saradeth T. Regular sauna bathing and the incidence of common colds. Annals of Medicine. 1990;22(4):225-227. doi:10.3109/07853899009148930
  5. Kunutsor SK, Laukkanen T, Laukkanen JA. Sauna bathing reduces the risk of respiratory diseases: a long-term prospective cohort study. European Journal of Epidemiology. 2017;32(12):1107-1111. doi:10.1007/s10654-017-0311-6
  6. Pilch W, et al. The effects of a single and a series of Finnish sauna sessions on the immune response and HSP-70 levels in trained and untrained men. International Journal of Hyperthermia. 2023;40(1):2179672. doi:10.1080/02656736.2023.2179672
  7. Kukkonen-Harjula K, Kauppinen K. Health effects and risks of sauna bathing. International Journal of Circumpolar Health. 2006;65(3):195-205. doi:10.3402/ijch.v65i3.18102
  8. Hussain J, Cohen M. Clinical effects of regular dry sauna bathing: a systematic review. Evidence-Based Complementary and Alternative Medicine. 2018;2018:1857413. doi:10.1155/2018/1857413
  9. Evans SS, Repasky EA, Fisher DT. Fever and the thermal regulation of immunity: the immune system feels the heat. Nature Reviews Immunology. 2015;15(6):335-349. doi:10.1038/nri3843
  10. O’Grady NP, Barie PS, Bartlett JG, et al. Guidelines for evaluation of new fever in critically ill adult patients. Clinical Infectious Diseases. 2008;46(Suppl 1):S148-S168. doi:10.1086/525143
  11. Prather AA, Janicki-Deverts D, Hall MH, Cohen S. Behaviorally assessed sleep and susceptibility to the common cold. Sleep. 2015;38(9):1353-1359. doi:10.5665/sleep.4968

Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician before using a sauna during illness, especially if you have underlying health conditions.