Traditional advice is to avoid saunas if you have uncontrolled high blood pressure. This was based on the assumption that heat stress would cause blood pressure to increase. New research suggests that sauna heat helps to dilate blood vessels, promote sweating and relaxation, and reduce arterial stiffness, all of which can help to prevent high blood pressure. You should still avoid saunas if your hypertension is not well controlled, however.
Saunas may prevent hypertension
A study from Finland followed 1,621 men over the age of 42, who did not have hypertension (defined as a blood pressure of greater than 140/90 mmHg) for almost 25 years. After adjusting for other factors, such as age, smoking, alcohol, glucose levels, fitness, family history of hypertension, income and weight, they found that men who had 2 to 3 sauna bathing sessions per week were 17% less likely to develop hypertension than those having 1 sauna session per week. For those having 4 to 7 saunas per week, the risk was reduced by 47%. The researchers concluded that regular sauna bathing is associated with a reduced risk of hypertension.
They followed up with tests in 100 men to try to find out why, and found that sauna bathing for 30 minutes reduced blood pressure and increased heart rate and blood vessel elasticity in the same way as medium-intensity exercise, while body temperature rose by approximately 2°C.
Immediately after 30 minutes of sauna bathing, average blood pressures reduced from 137/82 mmHg to 130/75 mmHg – a reduction of 7/7mmHg. Thirty minutes later, systolic blood pressure (the upper figure) remained lower compared to before the sauna, too.
Sauna therapy for hypertension
The effects of having a sauna alone or a sauna after exercise (30 minutes on a stationary bike) was tested in 16 people with untreated hypertension. In those who had a sauna alone, there was no significant change, but in those who had a sauna and exercised, systolic blood pressure was 3mmHg higher when measured 2 hours after the sauna (not significant compared to a control period) while in those who had a sauna after exercise, blood pressure was significantly reduced by 8/2 mmHg when measured 15 minutes after the sauna. Blood pressure was back to the pre-sauna readings within 2 hours, however.
Another study involving people with untreated hypertension found that a single sauna session could produce significant changes in nerve control of heart rate and blood pressure, although these changes came back to normal within 15 to 120 minutes. They recommended that additional studies investigated the effects of regular sauna bathing in people with hypertension.
Saunas and blood pressure medication
The effects of a Finnish sauna on blood levels of the antihypertensive drugs, propranolol (a beta blocker) and captopril (an ACE inhibitor) were studied in 8 healthy volunteers who had a sauna bathing session within an hour of ingesting the drugs. Not surprisingly, the fluid loss associated with a sauna significantly increased the maximum concentration of the drugs, but sauna bathing did not lead to significant changes in blood pressure or heart rate compared to the control period (although none of those taking part had hypertension).
So should you have a sauna if you have high blood pressure?
If you have untreated hypertension, you should avoid saunas until your blood pressure is well controlled. People with uncontrolled hypertension are at risk of increased blood pressure during or after a sauna.
Even if you have well-controlled high blood pressure, consult your doctor before having a sauna.
Drink several glasses of water before and after a sauna to prevent dehydration.
Measure your blood pressure before and after a sauna (every 15 minutes until readings are stabilised) to see how you respond as an individual – everyone is different.
Don’t have a sauna alone, or when you are ill or have been drinking alcohol.
If your blood pressure is raised, self-monitoring is key to maintaining good control.
Click here for advice on choosing a blood pressure monitor to use at home.
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