- Sauna bathing has many benefits for healthy people, but it is best avoided in some conditions.
- If you’re unwell, always consult a doctor before deciding to visit a sauna.
Why consider a sauna at all?
Saunas come in various types, each differing in heating temperature and humidity levels. While a Finnish sauna has a temperature of 80‑100 °C with a humidity of 5‑25%, a steam room will warm you up to a maximum of 50 °C but with 100% humidity. Regular sauna use has many benefits for healthy people, including positive effects on the heart and blood vessels and the immune system, help with headaches and joint pain, and, of course, relaxation and mental health.
Another option is the infrared sauna, which uses infrared radiation to heat the body. These saunas typically operate at temperatures between 45–60°C. Unlike traditional saunas, infrared waves penetrate deeper under the skin (up to 4 cm), allowing a deeper heating of the tissues. Their lower temperatures make them a gentler option for those who may find Finnish saunas too intense.
However, despite all the benefits of sauna use mentioned above, the situation can be quite different for people with certain types of illnesses. Visiting a sauna without first consulting a doctor can cause harm.
So when can visiting a sauna be risky?
1. Certain heart conditions
One of the most serious theoretical risks associated with sauna use — and the 12 hours following a session — is sudden death. This is a condition where a person dies unexpectedly without prior signs of illness. In such cases, undetected heart disease is often the underlying cause, potentially triggered by the physical strain of activities like sauna use. Overall, however, the risk is very low in the case of sauna use, and in the case of undetected heart disease, the risk is the same for sports, for example.
However, not all heart disease is a contraindication to sauna use - it appears that some stable medicated patients can safely use the sauna. In this case, however, a thorough examination and consultation with the treating physician is needed, and may also depend on the stage of the disease, etc.
However, you should avoid the sauna if you have unstable angina (chest pressure), are shortly after a heart attack, or have aortic stenosis (a defect in one of the heart valves). The high temperatures in the sauna put a strain on your heart and circulatory system, which your body may not be able to handle with the above conditions.
2. High or low blood pressure
Exposure to heat followed by cooling is the key mechanism behind the positive effects of sauna use in healthy individuals. However, if you suffer from high or low blood pressure, these sudden changes can be risky for you. Staying in high temperatures promotes blood circulation and dilates blood vessels, causing blood pressure to drop. This puts people with hypotension at risk of dizziness, confusion or even loss of consciousness.
In terms of hypertension, uncontrolled hypertension that exceeds 140/90 mm Hg, or at least one of these values, is particularly risky. Even with lower, but still elevated, blood pressure values, we recommend consulting a doctor before visiting a sauna — in some cases of milder hypertension, regular sauna use can have a positive effect on blood pressure levels. It is always up to your doctor to assess the possible benefits and risks in relation to your overall health.
3. Acute illnesses, colds and fever
While sauna use offers many health benefits for otherwise healthy individuals, it is a form of acute stress that requires the body to adapt. This adaptive mechanism is what boosts the immune system. However, if you’re already ill or battling a cold, the stress from sauna use can backfire. When fighting an infection, your body focuses its resources on recovery. Forcing it to manage the additional stress of sauna heat may weaken your defences and even risk spreading the infection further.
Therefore, if you have an acute infection or even a fever, forget about the sauna for a while and just "sweat it out" at home in bed, in peace.
4. Epilepsy
Heat and dehydration are potential triggers for epileptic seizures, as is alcohol consumption. Therefore, it is generally not recommended for people with epilepsy to visit a sauna. However, exceptions may be possible depending on your overall health, but these should only be determined by your GP. If a person with epilepsy does visit a sauna, they should always be accompanied by someone who is familiar with first aid principles for seizures and can help prevent or manage one if it occurs.
5. Some skin diseases
Although the sauna may have a beneficial effect on the appearance of symptoms in some skin conditions (eczema, psoriasis, etc.), others may worsen with sauna use. Conditions like cholinergic urticaria or wet rashes can be aggravated by the heat and humidity of a sauna.
To prevent the spread of infections in sauna or shower environments, it is also advisable to avoid saunas if you have conditions like warts. Of course, it also depends on the severity of the warts, their location and whether the spread can be prevented. In this case, consult a dermatologist.
6. Alcohol consumption
If you have a few beers in you and you thought you might want to warm up at the end of the day, we recommend taking a warm shower and leaving the sauna for another day. In fact, studies have shown that alcohol consumption increases the risk of dehydration, a significant drop in blood pressure, fainting or even irregular heart rhythms.
What about menstruation or pregnancy?
Menstruation
Opinions on sauna use during menstruation vary. For some women, the heat can help relax muscles and alleviate cramps, while for others, the stress of high temperatures may worsen their symptoms. If you’re considering visiting a sauna during your period, it’s a good idea to consult your doctor, taking into account factors such as your cycle length, bleeding intensity, and overall health. Keep in mind that high sauna temperatures can sometimes lead to heavier bleeding.
It is also very important to think about hygiene conditions in the sauna. As most saunas are water‑free environments, tampons or menstrual cups are generally the most suitable sanitary products. However, due to the increased heat and humidity, it’s advisable to change these more frequently for optimal hygiene.
Pregnancy
Sauna use during pregnancy is a more contentious topic. While some specialists advise avoiding saunas entirely throughout pregnancy, others are more flexible, particularly after the first trimester and if the pregnancy is progressing without complications. A 2017 systematic review found that using a sauna under controlled conditions—up to 20 minutes at 70°C with 15% relative humidity—was deemed safe for the women involved. However, it’s essential to recognise the potential risk of a drop in blood pressure, overheating or increasing dehydration, which could theoretically have a negative effect on the fetus. However, studies are very limited in this area, as any research on pregnant women is always ethically difficult to implement.
Therefore, it is always important to consult with your doctor when visiting a sauna, as there are many variables within each woman's health that can determine if it is (un)safe.
Bottom line
There are many benefits to sauna use for healthy people, but for certain diseases or conditions, it's best to avoid it. For example, heart disease, epilepsy, blood pressure abnormalities, or pregnancy or alcohol consumption can be risk factors. In all cases, however, consult your doctor first. For example, not all heart conditions are contraindications. It is always important to assess your overall health.
