Literature Review & Comparison Studies of Sauna / Hyperthermia in Detoxification: Part 1

Literature Review & Comparison Studies of Sauna / Hyperthermia in Detoxification: Part I

Heat for cleansing the body has been used by the Greeks, Romans, Turks, Russians, Asians, Australians, and Mayans, as well as the Native Americans. The oldest form of "Heat Stress" recorded in literature dates back centuries. The Greeks realized the value of heat (460-377B.C.) when Hippocrates said "Give me the power to create a fever and I shall cure every illness."

Over 2000 years ago the Romans considered the "Heat Bath" a place to unwind. It is recorded that the Chinese packed the body in "Hot Sand," the Japanese used "Hot Water Soak Baths," the Russians used "Steam Baths," the American Natives used "Sweat Lodges," and the Finns used "Sauna Bath" with either dry or moist heat. Though there is little recorded about Australian culture, eye witness reports the Aborigine's use of different colored clay to remove "illness, poison, or evil" from the-body. By placing clay packs over certain portions of the body, then slowly turning the body over the heat and smoke from a flameless fire, the poisons are drawn out into the clay as demonstrated when the discolored shell is removed.

In Pre-Christian Finland, the sauna was a holy place. Fire was considered a gift from the Gods and the sauna was the answer to heal all ills. An old Finnish saying goes "If the sauna can't cure it as the last resort, nothing can." The Finnish immigrants considered the sauna a necessity of life and built their crude log sauna first and later began working on their home. According to the old proverbs, the sauna was "the medicine of the poor," "the hospital of the poor" and "the medicine of Finland."(1) American culture has more closely followed the Finns in the style of the sauna (a suitable wood, resin-free, smooth with no splinters, and with a pleasant natural scent). Most are now heated by conventional electric heaters.

The review of the history of the sauna reveals that heat-stress is an effective method of removing fat-stored toxins from the body. However, there must be careful supervision and knowledge regarding the nature of the toxins being manipulated and their potential effect on the human body. For this reason, any type of heat-stress program for the removal of toxins should not be attempted without proper supervision. It is important to have laboratory evaluations to monitor the effect on both the kidneys and the liver. This will be discussed under the detoxification method.

Literature review indicates "heat stress" can remove the deposits from the blood vessels, and break down the scar tissue from the walls of the blood vessels, as well as release the fat stored toxins. This will be discussed in detail later in this article.


In addition to the brief history mentioned above, this review revealed that almost all the articles written on the sauna were written in a language other than English (generally Romantic or Slavic). The first foreigner known to have written about the saunas was Ibn Dasta, an Arab in 912 A.D.(2) The first medical thesis on use of the sauna was written in Finland in 1832 by Dr. Elias Lonnrot.(3) The first book in English was published in America in 1963 and was Sauna, The Way to Health.(4) In 1966 Physiological Effects of Extreme Heat as Studied in the Finnish Sauna Bath(5) was published by two doctors in the American Journal of Physiological Medicine. This thorough review of the literature deals with the physiological influences of the sauna.

In 1986, "Man in the Sauna" was published by two Finnish doctors who were the first to report scientific rationale for the sauna. This article was published in the Annuals of Clinical Research and contained 104 references.(6) The authors commented that researchers interpreted largely, according to their own biases toward the sauna. "It seems unreasonable to call just about any hot air exposure in an enclosed space a sauna." However, the name "sauna" has been adopted for a variety of conditions ranging from plastic bags(7) to conventional Finnish saunas and traditional smoke saunas, with temperatures ranging from 43øC(8) to 120øC(5), and air humidities ranging from a relative humidity of 3%(8) to 50%(9), and time in the hot room from ten minutes to several hours.(10,11) The British Medical Journal felt compelled to title a review of this excellent article "Sauna; Killer or Healer?"(12) and concluded that "the sauna has no proven benefit in promoting fitness or preve nting illness," and that "a long hot bath might be just as effective."

In 1987, an update of "Man in the Sauna" was published by the Finnish Sauna Society to celebrate its 50th anniversary in 1987, which was named "Finnish Sauna Year."(13) To date, no editorials have appeared on this issuance. It is against this type of misunderstanding about the role of saunas in detoxification that the literature was reviewed to find papers that would potentially be useful to physicians prior to their decision whether to engage in this type of protocol or not.


In Finland today, saunas outnumber cars.(14) There are approximately 1.4 million saunas in a country of 5 million. Since the use of the sauna occurs once to several times per week, the average Finn will be exposed to exceptionally strong heat several thousand times during his or her lifetime.(3) They do not consider this bathing, but sweating? Sauna has been known to them as a place of birth rather than of death.(15) A study of old Finnish magic verses often mentions earth, water, air and fire as sources of disease, but only rarely the sauna.(2) Massage, cupping, and bleeding were traditionally performed in the sauna.(16) One of their old sayings goes "if the sauna, schnapps and tar don't help, then the illness is fatal."(14) The Sauna Society of Finland defines 176øF (80øC) to 194øF (90øC) at the face level of the bather and a humidity of 50 to 60 grams of water per cubic meter as appropriate sauna conditions.(17) In large saunas the preferred temper ature is about 10øC higher and in small saunas about 10øC lower than the figures above.(18) Inadequate or defective ventilation induces a tired feeling in the bather, therefore the air must be exchanged from 3 to 8 times per hour.(19) These conditions have been derived from current physiological and technical knowledge about the sauna as well as conditions empirically evolved over the centuries.

A sauna is not the Japanese Ofuro, the Chinese Hot Sand, the better known Turkish Bath, the Salubrious Roman Tepidarium, nor is it the American Indian Sweat Lodge, Stone Sweat Bath, Sweat Tent, or Sweat Hut? Even the Swedish Bath, somewhat like the Finnish Sauna has its own characteristics including the traditional Swedish Massage.

The sauna is generally constructed out of relatively inert materials (glass, tiles, wood).(14) In Finland the sauna is often used improperly. In a survey of 10,000 people, 20% admitted they stayed in too long, and 40% behaved in a non-recommended manner after leaving their sauna.(14) Therefore, even in Finland some people experience the sauna as unpleasant, causing mild malaise, dizziness, headache, and restless sleep. This behavior only adds to the reluctance of the medical community to embrace sauna therapy.(3)

Given the facts presented thus far, it is obvious that the type of facilities that patients are being treated in for detoxification procedures bears only a slight resemblance to the traditional sauna.(20) In order to achieve proper treatment procedures for detoxification purposes several important changes must be noted. The type of material used to manufacture the room itself must be all natural, untreated, and free of any chemical resin. Plastic chambers presented a real problem, as did any wood that had been treated. It is imperative to have adequate ventilation, with an exchange of air appropriate to the size of the room. The degree of temperature as well as the length of time in the heat, not only cumulative but at each sitting, is essential. Someone trained in "BioToxic Reduction(TM) Treatments" needs to monitor the detoxification process to assure standard expected results. It is necessary to maintain a set range for temperature, as well as length of time in the "heated r ooms." Any alteration of proven protocol will not bring desired results. It has been recommended that these "heated, treatment rooms" be referred to as "thermal chambers."(21) By changing the name to "thermal chamber" it clarifies for the patient and the medical community that these rooms are "treatment chambers" rather than the image "sauna" engenders. The reports on "Thermal Chamber" treatments will follow. This will document the advantages and hopefully overcome some of the objections to the treatment.

Physiological Effects

Sauna bathing has been described as exposing the body to a hot environment,(17) with the exposure characterized by severe heat exceeding all natural environmental temperatures and the brevity of the exposure.(7) Review of various reports indicates that the temperature has ranged from 109øF to 248øF and the humidity from 3% to 50%.(7,9,17) The exposure time ranges from minutes to hours.(7,9,17) To the body, a sauna is rapid, severe heat stress. The person taking the sauna is externally at rest but the sauna temperature challenges the body's homeothermia.

The stress of the high temperature results in several hormonal responses to the body. To maintain a normal core temperature, about 98.6øF, the heat loss mechanisms of the body are activated(6) consisting of sweating and maximized cutaneous circulation with concomitant decrease in circulation to the muscles, kidneys, and viscera.(5) As the temperature rises, it speeds up both the metabolic rate by Van't Hoff's Rule and the oxygen consumption rate? This sets up the requirements for the pulmonary ventilation and circulation.(5) The sweating leads to loss of water and electrolytes, which the body tends to regulate through the kidneys? The water loss combined with maximal cutaneous circulation lowers the arterial blood pressure and cardiac output compensates for decreased peripheral resistance by increasing the pulse rate to 100-160 beats per minute. The diastolic blood pressure often falls, but systolic pressure goes up(9,22-25) or down(26-29) depending on how effective cardi ac output compensates for decreased peripheral resistance. Immediately upon leaving the hot room the body temperature rapidly begins to return to normal and within a couple of hours, (24 at the most), the whole organism has returned to a normal state.


The sensation of heat induces forceful sweating which leads to rearrangements of the blood distribution noted by reduction in muscle, renal, and visceral blood flow, reduction in central blood volume, release of ADH into the circulation, and water conservation by the kidneys.(30) These changes are noted by a decrease of the central venous pressure which may be the limiting factor for the circulation. This would then conclude that the altered central venous pressure must be seen first as a monitor of the fluid deficit and as a factor controlling cardiac function. When the skin temperature reaches 40ø to 41øC, cardiac output has increased by about 6.6 L/min., visceral blood flow decreased by about 0.6 L/min., and muscular blood flow decreased by about 0.2 L/min., the mean arterial pressure decreased a little or not at all, atrial pressure decreased, cardiac stroke volume increased somewhat, the heart rate increased considerable and the central blood volume which init ially decreases, increased above the original volume.(30) Hypohydration is the cause of the increase in heart rate.

All the studies done in authentic saunas confirm that the sauna influences the cardiovascular system in the same way as exposure to a hot environment.(31) There may be no prodromal warning preceding marked physiological changes that can occur in the first few minutes in the sauna. In one study, one subject developed an angina attack and three developed syncope. In Finland, where the incidence of myocardial infarction is one of the highest in the world, it is very rare that sauna precedes a myocardial infarction.(32) Other studies reported that systolic time intervals measured after profuse sweating can give a false impression of cardiac function.(33) One report found that insulin absorption from a subcutaneous injection site increased markedly from sauna bathing.(34) Another study concluded that the increased uptake of transdermal trinitrate under sauna bathing may be undesirable to angina patients.(35)

Two studies dealing with arrhythmias, concern the same 60 subjects, 33 male and 27 female.(9) Of these, at least 10 were accustomed to weekly sauna for a period of no less than one year but, the remaining 50 subjects were unaccustomed to the sauna. Twenty subjects were overweight, six had untreated hypertension and ten were in excellent physical condition. The sauna temperature was 80ø to 90øC and the humidity was 30% to 40%. The mean average time in the sauna was 17.4 minutes by which time the mean rectal temperature was 39.2øC and the mean skin temperature rose to 40.4øC and the forehead of one subject was 44.4øC.

In another study of 17 healthy and 18 myocardial infarction patients, reactions to the sauna were investigated.(26) All were men that were accustomed to the sauna. The research sauna was hot (90ø to 110øC), however the humidity was not revealed in the publication. The subjects were in the sauna for ten minutes and by the end of the sauna exposure the mean sublingual temperature of the healthy subjects was 38.1øC.

The above experiments were done in England and Israel which is thought to be a significant cause for the reported arrhythmias and other disturbances. Neither the duration of the exposure nor the temperature was high in comparison with the normal Finnish sauna. In addition, the subjects were unaccustomed to the sauna, which in a situation like this added factors such as fear, anxiety, hyperventilation, among other factors leading to alkalosis as a physiological phenomenon which interfered with the results. All these factors add to the possibility of arrhythmias. Also, poor ventilation of the sauna may increase anxiety and induce hyperventilation which may show as depression of the ST-Segment on the EKG. Myocardial Ischaemia is in extreme cases the cause of the EKG changes.

The prevalence of arrhythmias as a response to sauna exposure was studied by Luurila in both myocardial infarction patients and healthy controls.(36) This study was done in Finland amongst subjects that were accustomed to sauna since childhood. The study consisted of 101 subjects and was larger than the previously mentioned studies. The same test subjects were also tested on bicycle ergometer. In keeping with the Finnish custom the temperature of the sauna was from 77ø to 88øC. The humidity varied as the subjects threw water on the heated stones at will. The length of exposure varied with the mean for the healthy 10.4 minutes. Few subjects experienced arrhythmias in Luurila's study but arrhythmias occurred in both groups. He examined 32 healthy controls, one of which showed supraventricular extrasystoles immediately after the sauna. Exercise testing induced occasional extrasystoles in 4 healthy males. In this group healthy controls no significant depression of the S-T segment was noted. In the myocardial infarction group a total of 68 arrhythmias were observed in association with the sauna in 8% and the exercise test in 18%. These patients also displayed depression of the ST-Segment more often with the exercise test than the sauna. These results are the opposite of the study by Taggart, et al.(26) on a smaller material. In spite of sympathetic stimulation and increased catecholamine secretion, arrhythmias are infrequent.

According to Luurila's studies,(36) a moderate sauna bath is quite safe for the heart even for the myocardial infarction patients. Reasonable sauna expsoure does not contribute to cardiac insufficiency as the blood pressure does not elevate nor does the heart load markedly increase so that even patients with medicated cardiac insufficiency(6,26,37) or post coronary bypass may take a sauna,(38) Even at submaximal or maximal sauna bathing the cardiorespiratory performance capacity is not affected. Hollmann(38) observed a 30% to 35% decrease in maximal aerobic power measured 5 to 15 minutes after a sauna which had caused a 2.5% reduction in body weight. In another study maximal aerobic power was reduced by 4% after sauna causing a weight loss of 4.1% of the body weight within 24 hours,(39) The deterioration of cardiorespiratory performance capacity after a sauna is mainly due to a decreased plasma volume and the accompanying impairment of cardiac function.(40) The rise in the minut e volume is due to the increase in the heart rate as the stroke volume remains unchanged.

In a study comparing the use of walking or sauna in the rehabilitation of hypertensive patients with ischemic heart disease following aortocoronary venous bypass, the group average value for peripheral microcirculation improved only in the sauna group. An ordinary sauna increases cardiac workload about as much as moderate or vigorous walking and less than a moderate bicycle ergometer load of 60 watts.(36,37) Habituation to sauna therapy decreases the sympathetic stimulation and cardiovascular responses.(41) Psychological experiences may be a reason for many defective judgments of the use of the sauna that appears in the literature.(41) Heart rate and blood pressure measurements are occasionally linked to psychological experiences rather than organic origins.(41) They can also be triggered by other borderline situations via the psycho-organic switching system.(41)

Two studies, in Finland, based on autopsy materials, give information on the most serious cardiovascular complication of sauna bathing, sudden death. All sudden or unexpected deaths have to be reported to the police and an investigation into the circumstances and cause of death is carried out. In the majority of cases an autopsy has to be carried out.

Among the autopsies performed during one year in Finland there were 67 deaths of natural causes, which had occurred during a sauna (22 deaths) or within 24 hours of taking a sauna (18 within 30 minutes, 11 within 3 hours and 15 within 12 hours after the sauna). In some of these cases the relationship between death and sauna may have been just a coincidence. Mean age of the 54 men was 60 years and that of the women 64 years. The cause of death was ischaemic heart disease in 53 cases, acute cardiac insufficiency in 7 cases, and cerebrovascular disease in 2 cases.(42)


Use of the sauna induces changes in the secretion of hormones, some of which are similar to changes induced by stress situations(43) (such as increased secretion of catacholamines)(32) and others characteristic of sauna exposure.(44) One study revealed that plasma Na, K, C1, or P was not, or only moderately, altered by exposure to acute heat. CO2 tension decreased while aldosterone and ACTH increased.(45,46) In a second study, plasma renin activity, angiotensin 11, and aldosterone levels increased substantially.(47) In a third study, no simultaneous change in plasma norepinephrine, epinephrine, cortisol, aldosterone, or metenkephalin levels was observed.(48) In a fourth study, Noradrenaline rose, but not adrenaline.(49) Many studies have attempted to sort out these contradictory observations.(50-53)

Although antidiuretic hormone is increased during sauna use, other factors may be responsible for the long term homeostasis of water balance and plasma volume.(11) Evidently, saunas induce an adaptive hormonal change of short duration.(54) Studies have shown an increase in plasma cortisol, corticosteroids and in serum growth hormone(46,55-57) which is less pronounced in older men.(58) In contrast to this, concomitant glucose infusion and heat exposure decreased the human growth hormone secretion.(59) In reviewing plasma growth hormone, epinephrine, and norepinephrine, some authors concluded that sauna hyperthermia is a strong stressful stimulus for anterior pituitary functions, but only a moderate stimulus for peripheral sympathetic activity.(60) Moderate sauna use resulted in an increase in plasma TSH and ACTH(61) with a more prolonged response in the evening. The concentrations of corticotrophin (ACTH) and thyrotrophin (TSH) do not rise with mild sauna use.(56) This difference resembled the different reactivity of TSH to the administration of exogenous TRH during various times of the day. Hypnosis had no effect on plasma hormones in unstressed subjects compared to the normal diurnal variations.(46) Serum prolactin is increased during sauna use from 113% to 1280%.(46,62) Robertshaw and Mills(13) reported that even minor heat exposure (45øC for 90 minutes) increases the plasma prolactin concentration by 53%. This prolactin elevation explains the transient amenorrhea that is frequently seen during daily sauna use.(57,63) Sauna use had no effect on testosterone production.(46)


During sauna use the heat bound in the evaporating sweat is the body's only means of maintaining a homeostatic core temperature. During ordinary sauna use a good half kilogram of sweat is excreted with men sweating more than women.(64) Men's sweat is more dilute than women's, therefore, they spend more time in the sauna. A Finnish sauna presents a heat load of 300600 W/SQ.M. of skin surface area.(65) Sweating represents a heat loss of about 50 W/SQ.M. in a wet sauna to 200W/SQ.M. in a dry sauna.(65) The excretion rate of sweat is controlled by the anterior hypothalamus, which also controls the amount of the cutanous blood flow.(66,67) The results of Verde, et al,(68) suggest that the composition of sweat is also actively controlled. Increased sweating reduces the extracellular fluid volume. As a reaction to the heat, peripheral circulation is increased leading to reduced central venous blood volume and as a response to the heat stress, the secretion of epinephrine is accelerated . All these factors accelerate the excretion of vasopressin (ADH). As a result more water than ions is lost in the sweat and this increases the osmolarity of the body fluids and hence promotes the ADH secretion which reduces the production of urine. Thirst is felt after a sauna bath. Plasma renin activity is increased in association with sauna use. The urine angiotensin II also rises within 20 minutes of sauna exposure. Kosunen, et al.,(47) reported that the plasma aldosterone also rose upon sauna exposure reaching its maximum about 30 minutes after leaving the sauna. Lammintausta et al.,(55) measured urine aldosterone, but never found any significant changes in it. The osmolarity of sweat is about 25% that of blood? Profuse sweating results in hypohydration which may lead to mild acidosis.(70) Rapid superficial respiration(48) assists in heat loss, but is not significant as to upsetting the acidbase equilibrium.(70)

Acclimatization of the sauna leads to a more effective sweating with a maximum rate of 2 liters/hour and a concomitant (20-40times) increase in skin circulation? Along with the sweat, sodium, potassium and chloride are excreted in the sauna just as in physical exercise.(66) However, more magnesium and calcium are lost.(66) Copper and lead were lower in the sweat of females than in males while zinc is higher.(71) There was no gender-linked difference in the loss of copper in sauna-induced sweat. The loss of iron was very marginal in sauna use.(72) There is some loss of nickel and mercury in sweat.(73) Mild metabolic acidosis is also suggested by the increased concentration of serum potassium.(74)

In a study on sauna use on 10 healthy young men it was found that the blood pH decreased, the arterial blood CO2 and 02 partial pressures increased.(75) One case involving lithium intoxication was reported in a 60 year-old man who precipitated the intoxication by the use of a diet of grapefruit juice and frequent saunas. He was also on other psychotherapeutic medications.(76)

Other authors have reported that sweating is a significant route for the excretion of trace metals and that concentrations excreted are inversely proportional to the volume of sweat produced.(64) Various chlorinated and volatile hydrocarbons have been measured in the sweat of those undergoing sauna therapy.(77-79) Sweating is also a significant route of excretion of toxic trace metals.(48-51,53,84,85) Free amino acids(80,81) and frameshift mutagens(82) as well as N-Nitrosoproline(83) have been isolated from sauna sweat. Various street and pharmaceutical drugs have been isolated in the sweat of those undergoing sauna therapy.(86,87) Some studies have also indicated that the sauna may be useful in the therapy of renal insufficiency, however this must be weighed against complications that could occur from dehydration if the patient was not carefully monitored.(8,88)

Weight Loss

In most detoxification programs in use today, weight loss is not recommended as it makes it harder to monitor the patient and keep the nutrition and supplementation in proper balance.(89,90)


Review reveals that the sauna relaxes muscles.(7) Drettner(7) has shown that during exposure the muscle circulation is decreased and nasal mucosa and cutaneous circulation increased. This probably accounts for the preference of sauna bathing by athletes after training.(91,92) Devries, et al. studied the influences of the sauna on the neuromuscular system. Their study comprised 16 subjects. The study was directed at two types of muscle. The frontal muscles (fewer muscle spindles) and the biceps (numerous muscle spindles). The EMG's from the muscles were recorded before, following a 20 minute rest from the sauna and I hour and 20 minutes after the sauna. It was concluded that sauna significantly reduces the activity of the neuromuscular system.(92,93) The strength of the influence is proportional to the pre-sauna resting level activity. This is not a general vagal effect according to Devries, et al.,(9) but is rather the result of the reduced activity of the gamma-motoneurons due to increased body temperature. Concurrently, the neural stimulation of intrafusal muscle fibers is diminished and correspondingly, the proprioceptive input is diminished. This phenomena leads to a decreased alphaneuron activity, a decreased resting level of neuromuscular function and hence, to relaxation. If a mild acidosis should develop in the sauna, the potassium depletion of the cells manifests itself in reduced neuromuscular function and muscular weakness.

S'Jongers, et al.,(91) report that immediately after a sauna the compression force of the hand muscles decreased, but the next day it is increased above the initial levels. Sauna has been accepted as a traditional means for treating rheumatism as the heat per se makes the joints more supple.(94) This is based on the fact that heat alters the physical properties of tendons and joint capsules, causing these tissues to stretch more when warm.(94) Heat also speeds up the circulation of the joint capsule and decreases the viscosity of synovial fluid.(94) As a result, nearly all men find sauna use helpful, whereas one-fourth of all women find it detrimental.(95,96) The day after sauna, rheumatic pain is increased and joint mobility decreased. Pain is more obvious in non-inflammatory diseases such as fibromyalgia, but it can be prevented by proper cooling.(95) Sauna use has resulted in transient decrease in tinnitus,(97) had a mild effect on intraocular pressure and the quality of vis ual motor control.(98) Individuals that have convulsive disorders that are under control by medications are able to take a moderate sauna safely and previously febrile diseases are not moved toward convulsions.(3)


The use of sauna has historically been thought to be able to cure a cold because a stuffy nose is relieved as the warm inspiratory air dilates the airways.(6) In response to the hot environment in a sauna, the respiratory frequency is increased and the tidal volume is reduced.(22,23,70) The vital capacity, the peak expiratory flow rate, and the forced expiratory volume in one second are increased or pulmonary ventilation is improved.(70) These changes are minor and of the order of 10%.(99) There is a quick return to normal after the sauna. It is possible that the larger changes that have been reported may have been induced by the experimental design. In these, either the temperature was high in comparison to the normal Finnish sauna or the duration of sauna time was greater. It is also possible that factors such as fear and anxiety could have led to hyperventilation as could poor ventilation of the sauna itself.(6) Experiments with rats on the effects of the sauna conditions on the respiratory tract and the lungs have been done. These indicate that in rats no pathological changes developed in the lungs(100,110) but the cilia of the trachea and the main bronchus did get slightly damaged.(101) Extrapolation of these studies must be done very carefully since the anatomy of the upper respiratory system of the rat differs so much from humans. The rat does not sweat as its heat loss mechanisms are in the tail and in panting.

The sauna has been used in the rehabilitation and treatment of chronic obstructive pulmonary diseases.(102) It has been claimed to decrease morbidity from inflammatory respiratory diseases.(103,105) On the other hand it may accelerate the inflammatory reaction of acute respiratory diseases and prolong the disease.

The sauna has been used for physiotherapy.(106) It decreases breathlessness and increases ventilatory function in chronic bronchitis and asthma bronchiole.(107) The cool shower after a sauna may be dangerous in obstructive pulmonary disease because the pulmonary arterial pressure may rise.(108) Sauna use for patients with asthma and chronic bronchitis resulted in a rapid time course of clinical symptoms and helped to return cardiodynamics to normal. This is thought to be due to a bronchodilatory effect (perhaps from epinephrine relaxing the bronchial smooth muscle.)(109-111)

During sauna therapy with the BTR Program(TM) on patients with documented chemical exposure, supported by positive laboratory confirmation, it was noted that asthmatic and pulmonary problems rapidly improved within minutes of being placed in the sauna.(112,113) Reduction in cardiorespiratory performance capacity after the sauna is primarily due to a decrease in plasma volume and the accompanying impairment of cardiac function.(40)


Sauna use affects the fluid, electrolyte and acid base balance. It also has effects on many endogenous regulatory mechanisms maintaining the balance between fluid compartments and appropriate distribution of the circulation blood.(69) Sweating induces a mild and transient increase in the hemoglobin concentration and hematrocrit (less than 10%).(93) The total white cell count increases. The lymphocyte and eosinophil counts decrease.(93) The thrombocyte count increases by about 10%. The adhesiveness of the thrombocytes increases and reaches its maximum (12%) above the initial level within one hour after leaving the sauna. The aggregation time is shortened by about 8% within one hour of leaving the sauna. The coagulation time shortens about 6-7% about 15 minutes after leaving the sauna.(93) These insignificant changes are compensated for by the accelerated blood flow rate and faster fibrinolysis.(114-116) The sauna-induced increased number and aggregation of thrombocytes probably r esults from aggregating thrombocytes being released from the lungs and the spleen. No evidence has been found that sauna use would provoke either thrombosis or a bleeding tendency.(15) No hemoconcentration in the absence of physical movement was noted.(117) The arterial pH was decreased by about 14% after one hour in the sauna and the systemic bicarbonate pool decreases by increased ventilation (increases the pulmonary pool of bicarbonate) rather than by metabolic acidosis (which can increase from dehydration.)(118) The above noted effects are far less prominent when sauna use is continued regularly for several weeks.

When sauna is used regularly there are only minor changes in blood viscosity and hematocrit along with slight variations in hematological measurements, calcium, and serum protein pattern. Another study of blood coagulation and fibrinolysis found no consistent changes.(116) Thus, it must be concluded that sauna use leads to adverse blood effects predominantly acutely, while long term effects seem to be negligible. It has been observed that there is an increase in circulating plasma vasoactive intestinal polypeptide during sauna use.(119) It has been suggested that these levels are related to compensatory mechanisms during heat exposure with vasodilation and heat loss. Another experiment concluded that the human organism activates and releases histamine from its compounds in tissue during thermal stress.(120) The experimental conditions in all these studies were harsh as compared to the traditional sauna merely used as a tool to induce dehydration so the results are only suggesti ve.(6)

The Immunological System

The sauna has traditionally been believed to cure illnesses the common cold in particular. This is partly due to the fact that during sauna use the stuffy nose "opens up" as the warm inspiratory air dilates the airways. Eininkel's study suggests that the sauna has a preventive effect on infections.(121) His study consisted of 44 kindergarten children who were all 4 years old and attended he same kindergarten. None of the children were previously exposed to sauna use. There were 22 children in the experiment group and 22 in the control group. The study was carried on over 18 months. The children in the experimental group were carefully introduced to sauna use. The first introduction was for only 1 minute then was subsequently lengthened to successive stays by one minute each time until after 8 weeks they were in the sauna 8 minutes with a cooling down for 10 minutes in a 25øC room. There is no information as to how the children in the study group washed themselves during the study (shower or tub bath). All children in both groups were healthy. Absenteeism was due to acute and recurrent respiratory tract infections, otitis media, etc. During the 18 month study the children taking the regular saunas were sick for a total of 313 days, and the children in the control group were sick for a total of 628 days. Einenkel(121) suggested that the better resistance in the children taking the regular sauna was due to antimicrobial influence of the raised body temperature in the sauna.

Hyperthermia induces semi-conservative DNA synthesis which can be hypothesized as increasing resistance to viral infections.(122) The results from one study concluded that the human organism activates and releases histamine from its compounds in tissue during thermal stress. Contradictory reports have stated on one hand, that after heat stress the serum immunoglobulin concentration has risen,(15,93) and then on the other hand, that heat stress has no significant influence on serum immunoglobulins.(123)

There have been increases in the leukocyte count and serum proteins along with a decrease in the eosinophil count.(93) The experimental conditions were harsh in these studies, compared to the traditional sauna.(10,123)


The search through medical literature reveals no unusual dermal problems with sauna use. In a few people with atopic dermatitis, an intense itch can be caused by sweating. Sweating may also initiate cholinergic uticaria.(124) (Recent reports indicate frequent chloracne which coincides with the increased exposure to hydrocarbons.) Sauna therapy in conjunction with detoxification programs has been reported to produce flashback phenomenon which may be dermally manifested as well as psychologically manifested. The sauna itself does not cause drying of the skin although incorrect washing habits may lead to this. It has been noted that skin transplants are more susceptible to burn.(31)

Sauna use has been used as a part of a multimodality treatment protocol in the treatment of mycosis fungoides.(127) About 10% of psoriatics feel better after sauna use.(128) Sauna use does not contribute to melanoma risk.(129)


In twelve medical students intense sauna use repeated 6 to 8 times within two weeks caused a reduction in the sperm cells. The decrease was greatest 30 to 40 days after the start of the sauna use.(125) Another study indicated that after one extreme sauna exposure (85øC for 20 minutes) there was a reduction in sperm count after one week that lasted for a total of five weeks.(126) No changes in the morphology were noted. Ultrastructural changes of the sperm cells were observed however. Sauna use does not appear to affect testosterone production.(46)


"The effects of the sauna bath on the pregnant mother" focused mainly on toxemia. An extensive study was done using 60 pregnant mothers during the last month of their pregnancy, 50 mothers with toxemia and 10 as healthy controls. The results revealed that the body of a healthy pregnant woman reacts the same as everybody else to the sauna.(130,121) However, it was observed that the fetus may develop a mild oxygen deficiency during a sauna due to the redistribution of the circulation from the viscera and muscles to the skin.(130)

An experiment with nonpregnant women of fertile age by Harvey et al.(133) was conducted whereby they measure the vaginal temperatures of women in the sauna (81.4øC) and in a hot tub bath (39.0øC and 41.1øC). Only a few of the women could remain in the sauna long enough for the vaginal temperature to reach 38.9øC which is considered the critical threshold temperature in regard to fetal damage.

About a decade ago there was concern over the possibility that maternal hyperthermia during the fourth week of pregnancy was a cause of anencephaly.(133-140) Careful review of the study of 63 who had anencephalic infants revealed that only two of the seven that had hyperthermia episodes were due to sauna exposure.(121) It was concluded that exposure at the period of anterior neural-groove closure implied that hyperthermia itself may be an etiological factor in anencephaly. This was in spite of the fact that the incidence of CNS defects in Finland (0.32/1000) for anencephaly is among the lowest ever reported.(141) It has also been pointed out that fever and hyperthermia are different matters.(142) Based on these investigations and the Finnish experience there is no longer any reason to believe that sauna use during early pregnancy is teratogenic.(141)

The hemodynamic changes brought about by sauna use are similar regardless of pregnancy state. There are however, differences in the hormonal responses and pregnant women adapt well to the thermal stress of the sauna.(143) Providing that the fetus is healthy it also adapts well to the sauna.(143)

Children and the Elderly

There are a few studies dealing with sauna use by children.(144-147) Children are characterized by a high sensitivity to heat stress and fluid loss due to their meager subcutaneous tissue, undeveloped sweating and large body surface to body mass area. This causes a child's heart rate and body temperature to increase rapidly.(38) Blood acidity increases mildly(148) and after the sauna the fluid requirements related to body weight is three to four times higher than in adults. Sweat glands are twice as dense (200/sq. cm) in children and become active after only one minute's stay in the sauna.(149) Children sweat at a higher rate than adults (20 g/sq. M/min. vs. 13 g/sq. M/min.) which are about a third lower. The physiological effects of the sauna demonstrate that the use of sauna is beneficial to children in a similar way as it is to adults.

In Finland children are familiarized with the sauna at the age of 4.5 months. Almost all preschool and school age children take a sauna regularly and 80% enjoy it.(150) Due to the above mentioned physiological features, the sauna may aggravate respiratory and other febrile illnesses in children more than in adults. Finnish parents, for this reason, observe the post-sauna use behavior of their children and this helps them to establish safe limits of exposure and to avoid any adaptation problems. Finnish children are rarely allowed into a sauna on their own until they are at least 7 years old.(151) As discussed earlier, it is often claimed in central and eastern Europe that regular sauna use will increase resistance to catarrhal infections.(6)

In the elderly, there is an increased prevalence of latent or manifest heart and other diseases that may increase the risk of complication from sauna use. Of those who died suddenly and unexpectedly 57% were over 60 years of age (1/400,000)just as in other aspects of living. The death rate in other ages was; 1/9,000,000 ages under 40; 1/2,300,000 ages 40-49; and 1/900,000 ages 50-59.(152,153) In this accounting the causality between sauna and death is not proven, only reported. Many of the deaths were related to the consumption of drugs,(154) exposure to carbon monoxide from propane heaters(155) or to alcohol intake. In Finland alcohol has been extimated to be the contributing factor in some 20 to 25 sauna-related deaths per year. It is thought that alcoholic consumption and sauna use may affect the body's ability to maintain blood pressure and as a result may cause fainting and accidents.(156) Alcohol intoxication and particularly during the hangover phase, exposes a person to cardiac arrhythmias.(156) Sauna use during this time may further increase the risk due to enhanced adrenergic activity.(156) Alcohol-related injuries such as sprains and burns are common in the sauna, however more serious accidents take place such as head contusion and heat stroke after passing out.(156)

Hyperthermic Oncology

In Finland, where sauna bathing is widely practiced, the incidence of breast and testicular cancer is much lower than in neighboring countries where the sauna is not used. The excellent result in Finland following lumpectomy and relatively low doses of irradiation for breast cancer may be attributed in part to the beneficial effects of the sauna. The sauna stimulated the reticuloendothelial system and other immune mechanisms, thus potentiating the response of the tumor to the radiation.(157)

The above information stimulated a review of "Hyperthermic Oncology," (1984) from Helen Coley Nauts of the Cancer Research Institute in New York. This study reviewed the many kinds of hyperthermia that have benefited cancer. The following is a quote from "Historic Aspects and Future Trends": "These include:

Acute bacterial infections, over 1,000 references 1775-1982;
Lightning, Eason 1776, Allison 1880;
"Electropuncture." Reading 1896;
live cautery, since 2,000 B.C.;
Hot full baths, Japan;
Sauna, Finland:
Electrocautery for cervical cancer, Byrne 1889-92, Percy 1912-16;
Local circulating hot water for cervical cancer, Westermark 1898;
Surgical diathermy and electrocoagulation, Strass 1915-69, Madden & Kandalaft 1967-83, Sykes 1983;
Hyperthermic perfusion of chemotherapeutic drugs to the extremities, Stehlin 1979-80;
Systemic fever due to trauma remote from the tumor, Vidal 1907-10;
Induced fever due to injections of milk, tuberculin, heterologous blood or transfusions, Konteschweiler 1918;
Timing of fever therapy combined with radiation, Warren 1935;
Combined fever therapy with chemotherapy, Richet 1937;
Fever therapy in mycosis fungoides, Wills and Hatfield 1925, Klauder 1936;
Pyrexal, Bonard 1959;
Effects of concurrent or prior tuberculosis or other infections on cancer incidence or prognosis, Tromp 1954, Meyer and Benjafeld 1955, Nauts 1980;
MBV, Nauts 1984.
It is suggested that the immune responses of patients receiving hyperthermia now and in the future should be stimulated by administering biologic response modifiers in order to potentiate the response of the tumor to the local hyperthermia and whatever other modalities are being given. The one which has produced the largest number of permanent results over the past 90 years is MBV (mixed bacterial vaccine) prepared from Streptococcus pyogenes and Serratia marcescens, formerly known as Coley's toxins, Nauts 1984 (390 references).

Next Month: Part II

The Sauna and Illnesses

References available upon request


Zane R. Gard. M.D.

P.O. Box 1791

Beaverton, OR 97075-1791

Article copyright Townsend Letter for Doctors & Patients.


By Zane R. Gard and Erma J. Brown

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