Hot Tub Use: Health Benefits and Risks
Hot tubs pose significant health risks including potential exposure to nontuberculous mycobacterial (NTM) infections and should be used with caution, especially for indoor installations where proper maintenance is critical for safety. 1
Potential Health Risks
Infectious Disease Concerns
- Indoor hot tubs are a recognized source of nontuberculous mycobacterial (NTM) infections, particularly Mycobacterium avium complex (MAC), which can cause hypersensitivity pneumonitis ("hot tub lung") 1
- Currently, there are no known methods for completely eliminating NTM from standing indoor water sources 1
- Mycobacteria are relatively resistant to common disinfectants and can grow in a wide range of temperatures, especially high temperatures 1
Prevention of Hot Tub-Related Infections
- Manufacturers universally recommend following regular maintenance procedures including draining and thorough cleaning of the tub and filtering system 1
- Bathing before hot tub use is universally recommended to reduce contamination 1
- For those with documented MAC hypersensitivity-like disease, complete avoidance of indoor hot tubs is recommended 1
Cardiovascular Effects
- Hot tub immersion causes systolic and diastolic blood pressure to decrease temporarily 2, 3
- Heart rate increases during hot tub immersion, though less significantly in hypertensive individuals compared to normotensive controls 3, 4
- For patients with stable coronary artery disease, short-term hot tub use (15 minutes at 40°C) produced lower peak heart rates and blood pressure compared to exercise, suggesting relative safety with appropriate time and temperature constraints 2
- Ten-minute hot tub sessions appear to be safe for most patients with treated hypertension, with blood pressure responses similar to normotensive individuals 3
Hematological Considerations
- Hyperthermic immersion can lead to minimal activation of blood coagulation and hemoconcentration 5
- Hot water bathing causes a decrease in plasminogen activator inhibitor (PAI) activity and an increase in thrombocyte count 5
- These changes are generally not significant enough to pose marked thrombotic or bleeding risks in healthy individuals 5
Safe Hot Tub Practices
- Time and temperature constraints are important: limit sessions to 10-15 minutes at temperatures around 40°C (104°F) 2, 3, 4
- Follow manufacturer's maintenance recommendations for cleaning and water treatment 1
- Always shower before entering a hot tub to reduce contamination 1
- Indoor hot tubs require more vigilant maintenance due to increased risk of mycobacterial growth 1
- Consider outdoor placement of hot tubs when possible, as this reduces the risk of mycobacterial aerosol concentration 1
Special Considerations
- Individuals with documented hypersensitivity pneumonitis from hot tub exposure should completely avoid indoor hot tubs 1
- People with cardiovascular conditions should consult healthcare providers before hot tub use, though short sessions appear relatively safe for those with stable treated hypertension or stable coronary artery disease 2, 3
- Immunocompromised individuals, including transplant recipients, should exercise extra caution due to increased susceptibility to NTM infections 1