Hot tub lung is a reactive lung condition associated with exposure to contaminated aerosol droplets present in places that use hot steam or vapors, such as saunas, spas, swimming pools, and the eponymous hot tub. A reactive lung condition is a non-specific term referring to a condition where the lungs respond to certain environmental triggers, usually with symptoms such as wheezing and mucus production¹.

While the prevalence of hot tub lung is low, serious respiratory consequences can result, especially among immunocompromised/immunosuppressed people. This makes it important to understand your risks and detect signs of hot tub lung early.

What Is Hot Tub Lung?

Exposure to reservoirs of hot water where there is steam, such as in saunas, spas, jacuzzis, swimming pools, or even the hot shower in your home, can pose a risk for developing respiratory consequences of hot tub lung - a type of hypersensitivity pneumonitis.

An inflammatory response to bacterial exposure in aerosolized steam droplets is responsible for the respiratory consequences of HTL.

What Causes Hot Tub Lung?

In most cases, a group of bacteria called non-tuberculous mycobacterium avium complex (MAC) is the primary source of hot tub lung reactions². However, other bacteria such as Pseudomonas aeruginosa³and Legionella pneumophilia⁴ have also been observed as likely sources of hypersensitivity reactions resulting in HTL.

The innate characteristics of the MAC bacteria favor sticking to the surfaces of these hot water reservoirs and enable it to withstand temperatures as high as 52°C/125.6°F⁵. MAC is also resistant to standard cleaning products containing chlorine⁶.

Frequently, a single episode of aerosolized exposure to such bacteria can be sufficient the develop the hypersensitivity pneumonitis observed with HTL. In some cases, especially with occupations that account for cleaning and maintenance of water reservoirs, repeated exposure results in ongoing and recurrent illness⁷.

How Do I Know if I Have Hot Tub Lung?

If you have a recent history of exposure to hot water vapors following which you notice a progressive difficulty with breathing, check in with your doctor to rule out the possibility of hot tub lung.

A review of medical literature indicates most cases of hot tub lung happen among middle-aged individuals, with an average age of 58.8 years, and one to 12 months of symptoms before accurate diagnosis⁸. Most infections have been documented among people with normally working immune systems and rarely among those who are immunocompromised⁹.

Possible symptoms of HTL can include a persistent dry cough, chest tightness, shortness of breath, low-grade fever, and unintentional weight loss¹⁰. Due to the persistence of irritating symptoms, many people increase their exposure to hot steam in an effort to relieve their cough, which can result in an exacerbation of symptoms if the source of the vapors is contaminated¹¹.

Diagnosis

Due to the similarity in symptoms, an initial diagnosis may include asthma, sarcoidosis (collections of inflamed cells that form lumps called granulomas), typical bronchitis, eosinophilic bronchitis, or occupational lung disease. 

Initial radiography, such as an X-ray or CT scan, may not aid in proper diagnosis, since finding spread-out growths with a ground glass appearance in the tissue surrounding the lungs’ air sacs (called diffuse interstitial nodular lung changes) can indicate several other infiltrating lung diseases¹².

A biopsy (sample) of lungs with HTL can show granulomas and lung inflammation, which can also be present with various lung diseases beyond HTL¹³. Additionally, a culture of the lung biopsy doesn’t always test positive for MAC bacteria, complicating accurate diagnosis further¹¹. 

It is a combination of the symptoms, a detailed history of hot tub exposure, and characteristic diagnostic findings that help to provide a conclusive diagnosis¹⁴.

How Is Hot Tub Lung Treated?

One of the key reasons why accurate diagnosis is necessary is to guide the treatment course for hot tub lung. 

Due to the likelihood of receiving an incorrect diagnosis for the symptoms of hot tub lung, you may be started on antibiotics and perhaps steroids. In some cases, this may reduce symptoms, but they often return, especially if there is continued use of hot tubs and exposure to steam⁸¹⁴.

Avoiding Steam Sources

Once the use of hot tubs is identified as the cause of your respiratory symptoms, primary hot tub lung is managed by promptly avoiding the hot tub and other steam sources. Additionally, if the contaminated hot water source is in your house, you should have it cleaned thoroughly.

Ideally, avoid hot steam exposure for at least a year following the resolution of symptoms.

For most patients with hot tub lung, the resolution of symptoms can be noted as soon as hot aerosol exposure is limited.

Corticosteroids

Since the symptoms in the lungs derive from a hypersensitivity reaction to bacterial exposure, many people with HTL benefit from a short course of corticosteroids, which help resolve underlying inflammation¹⁵. Steroids can also tackle residual symptoms such as a persistent cough and chest discomfort.

Antibiotics

Antibiotic therapy is rarely used to treat HTL, despite bacterial contamination being the primary source. Doctors consider it in cases where steroids and hot tub abstinence fail to reduce symptoms¹⁶. Antibiotics are also useful among people recording severe respiratory symptoms who are immunocompromised.

The American Thoracic Society recommends a combination of azithromycin, clarithromycin, ethambutol, and rifampin for a minimum of 12 months to manage MAC infections¹⁷.

Other Non-Pharmacological Management

Some cases of hypersensitivity pneumonitis, such as those seen with HTL, benefit from non-pharmacological management approaches, such as the previously mentioned avoidance of hot tubs. Pulmonary rehabilitation and supplemental oxygen have been shown to improve respiratory endurance and reduce episodes of hypoxemia associated with severe cases of hypersensitivity lung reactions¹⁸.

How to Avoid Hot Tub Lung?

Since hot tub lung is linked to contaminated aerosol exposure, limiting your hot tub time is the best method of prevention.

Additionally, if you have a hot tub or other sources of steam vapors at home, ensure you have it cleaned regularly and thoroughly. Ideally, even after you have your hot tub cleaned, if you’ve had HTL avoid exposure for at least a year to allow time for your lungs to heal and prevent the recurrence of symptoms.

HTL can sometimes be a consequence of occupational exposure¹⁹²⁰. In such a case, identifying the contaminated source and avoiding those areas is crucial. Additionally, consider taking a break from steam and vapor exposure in general, which can help improve your respiratory symptoms. If you cannot avoid steam, vapor, or dust exposure due to your occupation, ensure you are using the best PPE available to reduce your exposure²¹.

Adopting lung-friendly habits can help prevent episodes of exacerbation and also aid with faster recovery. Some of these include smoking cessation, regular exercise, and getting your yearly flu shots.

The Bottom Line

Hot tub lung is a treatable lung condition when accurately diagnosed. Since it can take substantial time following exposure for symptoms to appear, the link to hot tub aerosol exposure might not be initially detected. Progressive shortness of breath, chest discomfort, and a dry cough should prompt you to seek medical help to rule out the possibility of a hot tub lung. Be sure to mention any previous exposure to hot aerosolized vapors when meeting with your healthcare professional. You can manage hot tub lung efficiently through the avoidance of hot vapor sources and steroids to reduce lung inflammation.

Dr. Michelle Frank

Michelle is a healthcare consultant and content creator with over six years of experience in the FemTech space. She contributes extensively to health forums, especially those centered on enabling wellness, advancing digital health, and FemTech solutions. She loves classic rock music, reading classic literature, and finding new spots in town for good food and some chai.

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