Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review

Table 3

Airway conditions and repeated sauna therapy.

Study characteristics			Study sample		Intervention		Comparators		Health effects	Adverse side effects
Author & year	Level of evidence	Design	Pop/; country		Sauna; type	Duration	Comparator/; control	Outcome; measures	Positive/negative/; negligible	None/mild/; moderate/; severe
2013-; Kunbootsri et al. [57]	I	RCT	Allergic Rhinitis/; Thailand	26	Thai/Finnish	6 weeks	Control group received education and usual medical care	HRV, peak nasal inspiratory flow and usual spirometry parameters	Positive,; reduced high-freq component (), increased low-freq component (), increased low freq: high freq ratio () in HRV analysis; peak nasal inspiratory flow improved (119.2 L/s ± 46.4 to 161.9 L/s ± 46.7, ); FEV1 (forced expiratory volume at 1 sec) improved (77.5%  ± 9.8% to 95.6%  ± 5.7%, ) in sauna group compared with control group.	None
2010-; Pach et al. [58]	I	RCT –; Single blinded	Coryza/; common cold symptoms/; Germany	157	Finnish	3 days	Face mask breathing hot dry air at 90°C, 20% RH in treatment group; Face mask breathing cool, dry air at 24°C, 20% RH in control group.	Symptom severity scoring (0–10) on four different days; intake of common cold medications daily during week of intervention.	Negligible,; on day 2 only, significant decrease in symptom severity in treatment vs control group [−1.0 (−2.0–−0.1), , 95% CI] but was not sustained through day 3, 5, 7 assessments.; Less cold medication taken on day 1 only [3% (1–9%) vs 15% (8–28%)] in treatment vs control group (, 95% CI).	Mild,; cough directly stimulated by face mask in both groups (2 in treatment group; 1 in control group).
2014-; Kikuchi et al. [59]	II	Controlled intervention trial	COPD/; Japan	20	FIR	4 weeks	Control group received usual medical care	Spirometry parameters; 6 MWT (6-minute walk test); modified Borg dyspnea scale; oxygen saturation; PR	Positive,; between-group improvements in FEF50 (forced expiratory flow after 50% of expired forced vital capacity) in sauna group [+0.08 L/s (0.01–0.212 L/s)] vs control group [−0.01 L/s (−0.075–0.04 L/s)], .	None
2008-; Umehara et al. [60]	III	Single group intervention, pilot study	Male COPD; Ex-smokers/; Japan	13	FIR	4 weeks	No control group	BP, PR, body wt, body temp; usual ECHO parameters; exercise tolerance by bicycle ergometer; SGRQ (St. George’s Respiratory Questionnaire) symptom scores; plasma BNP, HCT, albumin before/after treatment.	Positive,; decreased SBP and DBP (–0.0002); improvements in RV function via increased pressure differential (); Pulmonary artery pressure during exercise decreased (); increased exercise time (360 s ± 107 s to 392 s ± 97 s, ); lowest SpO2 during exercise increased (); symptom scores improved (59.7 pts ± 16.9 to 55.3 pts ± 17.2 pts, ) after sauna.	None

COPD = chronic obstructive pulmonary disease; FIR = far-infrared sauna; PR = pulse rate; HR = heart rate; BP = blood pressure; SBP = systolic blood pressure; DBP = diastolic blood pressure; wt = weight; temp = body temperature; HRV = heart rate variability; freq = frequency; RH = relative humidity; ECHO = echocardiogram; BNP = B-natriuretic peptide; E/LFTs = electrolytes with liver function tests.