WARNING – This article may put you off hot tubbing. If you continue reading remember a well maintained hot tub is unlikely to give you a disease or infection. Also, most people get sick from using public pools and hot tubs and not their home hot tub. If you are a person who prefers not to know things, then stop reading now!!
Hot tubs can harbour viruses and bacteria that cause infections which may make you sick, but all are preventable. In this article, we look at some of the diseases you can contract from unclean hot tubs and look at ways to treat them. If you are thinking of purchasing a hot tub or spa, do not let this article put you off. I have written articles on the many benefits of hot tub use, so please read those to get a balanced overview. The main thing to remember is a well maintained hot tub is extremely unlikely to make you ill.
Legionnaires disease from a hot tub
Legionnaires disease is a bacteria that breeds in clean water that is not moving. It is found naturally in water and is one of the reasons chlorine is added to tap water. If this bacteria gets into peoples’ lungs, it causes severe pneumonia that requires medical treatment. People with chronic lung problems and the elderly are most susceptible to contracting the disease, but anyone of any age can contract it. The bacteria are transferred from the hot tub to your lungs in contaminated aerosols that are produced by the steam, water jets and bubbles. Once they get into your lungs they multiply and cause pneumonia.
Signs and Symptoms of legionnaires
Legionnaires disease initial signs are similar to flu symptoms. Sufferers may have a fever, feel tired and have aching muscles and joints. These symptoms can start to manifest in anything from 3 days to three weeks, but most patients exhibit symptoms after a week. As the disease takes hold, it will begin to affect the lungs and become more apparent.
Early treatment and detection is enormously important, so if you suspect you may have Legionnaires, then you must see your medical practitioner as soon as possible. Treatment is generally with IV antibiotics, but this will be determined by the health professionals looking after you. If you are unlucky enough to contract this, be prepared to answer many questions from the hospital staff. They will be trying to determine where you contracted the infection so that others are not put at unnecessary risk.
The disease often presents in clusters, which means one family may get ill or a few people from the same neighbourhood fall unwell. This helps medical professionals determine the source.
Preventing Legionnaires disease in a hot tub
A well maintained and clean hot tub will not pose a legionnaires risk – so please do not let this article put you off buying or enjoying hot tubs! A safe hot tub has well maintained sanitiser levels that kill bacteria. In unclean hot tubs, it is challenging to keep the needed sanitiser level because the chemicals are being overwhelmed by the grime and bacteria. If you notice your chemical level falling quickly below safe levels, then you need to perform a shock treatment to the water.

Shock treatments should be performed weekly or after heavy use (like a party). A chlorine shock increases the level of chlorine to over 10 ppm for over four hours, and a non-chlorine shock reactivates the bromine levels. You will also need to clean or change the filters regularly and carry out a full water change and pipe clean every 3-4 months.
Want more information on hot tub maintenance? Find out more here.
Hot tub rash – infection – Folliculitis
Folliculitis is a rash that is caused by another bacterium, Pseudomonas Aeruginosa and like Legionnaires, it thrives in warm water. The bacteria gets into the hair follicles causing an itchy rash. The rash is caused by exposure to any un-clean water such as rivers or lake, but it is more likely in warmer water because the heat encourages pores to open, allowing access for the bacteria.
Signs and symptoms of hot tub rash
The condition starts off as an itchy rash that can cover most of the body but generally covers the trunk. The outbreak turns into bumps, then puss filled nodules that are often confused with the highly contagious chicken-pox. Sufferers in some cases also have a fever. The onset of symptoms can come in a few hours but generally, appear the following day.
Treatment of the folliculitis infection
The rash goes typically on its own after 5-10 days, but many sufferers use an antihistamine to help control the itching. In some severe cases, antibiotics may be indicated especially in children who are generally more susceptible to the condition.
Prevention of hot tub rash
Once again this comes down to hot tub good practice. The filters need regular cleaning, and the sanitiser levels need to be maintained. Encouraging showers before entering the hot tub is also a sensible precaution. Unfortunately, showering after exposure does not help prevent the condition or reduce its severity.
Just to put a little perspective on this – you are more likely to get hot tub folliculitis by not washing and drying your swimsuit following a swim or by staying in a wet swimsuit all day next to the pool. I think it was just associated with hot tubs as the rash can cover more of the body. Also, my family and I have been using hot tubs for many years and have never experienced any of the conditions detailed in this article!
Hot tub lung
This condition is so rare; I considered not writing about it. Those of you who have read my articles before may already know that I work in a teaching hospital and have access to medical journals, so I took the time to look into hot tub lung as some of the things I have read on the internet sounded more like click-bate than facts!
What is hot tub lung?
Hot tub lung is diffuse granulomatous lung disease caused by inhaling mycobacteria. Like with Legionnaires disease, these mycobacteria enter the lung through contaminated aerosols caused by steam, waterjets and bubbles.
Signs and symptoms of hot tub lung
Presenting symptoms again mirror flu symptoms with fever, cough, chest pain, tiredness, joint and muscle ache. Shortness of breath is the main symptom, and this seems to be why most patients present to the medical team. A few patients also have weight loss.
Prevention of hot tub lung

This, of course, includes proper hot tub maintenance and keeping sanitation chemicals at the correct levels. But most of the case studies I read described cases where people were exposed to large amounts of bacteria over a long period; suggesting that ventilation may be crucial in reducing the risk of this disease. I also haven’t found any cases in the literature of healthy individuals contracting hot tub lung from routine hot tub use. One of the examples I read was a pool maintenance guy who used a jet wash to clean the filters every day at a public spa. Cleaning the filters with a jet wash produced a lot of contaminated aerosols which resulted in him contracting hot tub lung.
Treatment of hot tub lung
By stopping the exposure to the contaminated aerosols, hot tub lung goes away naturally; suggesting that the condition is an autoimmune response caused by a hypersensitivity to the exposure rather than an infection. (What does this mean?) This means that the chance of you getting hot tub lung is very small if you are healthy and use a hot tub correctly! If you are getting shortness of breath, of course, you should see your physician anyway to rule out other medical conditions, but it is unlikely to be hot tub lung!
Will my hot tub make me sick?
No – not if you maintain it and keep the water clean!
You should take extra precautions if you have a hot tub party. Before the party ‘shock’ the hot tub, so you know the sanitising chemicals are working at their optimum level. After your party shock the water again or consider changing the water altogether. For regular family use, stick to your routine maintenance regime.
I really hope I haven’t put anybody off buying a hot tub or using their existing tub. That was not my intention, but I think it is worth knowing what could happen if you do not look after the hot tub. As I said, my family have used hot tubs for years and have never experienced any problems whatsoever. The health benefits of using a hot tub vastly outweigh the potential risks of these rare conditions.
Are you thinking of buying a hot tub? (even after reading this!!) If so check out this article detailing why an inflatable hot tub may be a good buy. Yes, I said “inflatable!!”
Have fun in the hot tub.
Brendan 😊
In the UK? – Click here to see the discounted price of my first ever hot tub!