When kept clean, maintained, and at a safe temperature, hot tubs can be an enjoyable way to relax and unwind. But they can also be breeding grounds for diarrhea-causing germs.

Hot tubs can evoke relaxation, but there are also some safety issues to consider. Like swimming pools, hot tubs need to be kept clean and sterilized to prevent germ-causing health issues. This includes diarrhea.

Read on to learn more about how using a hot tub may cause diarrhea, how to prevent illnesses, and when you may need to call a doctor.

If you have three or more loose stools in a day, you may be experiencing diarrhea. Depending on the underlying cause, diarrhea can also cause abdominal pain, cramps, or flu-like symptoms.

The act of sitting in a hot tub itself isn’t likely to cause diarrhea alone. Instead, it’s the presence of certain germs in the water, such as bacteria, parasites, and viruses, that can lead to illness and subsequent diarrhea when you’re exposed to them.

Some of the most common types of germs that may be present in hot tubs or pools include:

  • Cryptosporidium (Crypto): This is a type of parasite that can survive in water as well as on foods and surfaces. It spreads through stools, and the most common symptom is diarrhea. Infections can last between 1 and 2 weeks.
  • Escherichia coli (E. coli): E. coli can cause diarrhea and may spread through contaminated food, water, and direct contact with other people who may be sick.
  • Giardia: Giardia is another type of parasite that may be present in hot tubs and pools from the stools of a person who has it. It’s known for causing diarrhea that occurs two to five times per day, as well as fatigue. Symptoms sometimes last for several weeks.
  • Norovirus: Considered the most common cause of diarrhea and vomiting in the United States, norovirus can spread through contaminated water and food. Symptoms may start within 12 hours of exposure and last for up to 1 to 3 days.
  • Shigella: Shigella is a diarrhea-causing bacteria that can spread through contaminated water and food. It can cause symptoms within 1 to 2 days and may last for up to 1 week. Diarrhea from this infection can also contain blood.

You may get sick if these bacteria are present in a hot tub and you get the contaminated water in mucous membranes, such as those in your nose or mouth.

Even tubs and pools that look clean and well maintained can still contain diarrhea-causing germs. Some may survive for several minutes, and others can survive for days in chlorinated water.

If someone who is sick with these germs uses the hot tub, you may be at risk of getting sick, too. This is especially the case if you accidentally swallow any of the contaminated water.

For these reasons, public pool operators often advise against going in the water if you’re having diarrhea. While some germs may be cleaned with filters and chemicals, these may not be enough to completely stop them before they reach other people.

In particular, Cryptoparasites have the longest lifespans, as they can survive in disinfected water for 7 days or longer.

Aside from developing diarrhea from exposure to contaminated water, there are other hot tub-related health risks to consider. Some of these risks don’t involve accidental water ingestion.

Legionella infection

Legionella is a type of bacteria that can lead to serious illnesses like Legionnaires’ disease or Pontiac fever. Unlike with E. coli or Shigella, you may contract it from breathing in contaminated hot tub steam.

Legionnaires’ disease can be life threatening. It’s important to seek emergency medical care right away if you’ve recently used a hot tub and are experiencing shortness of breath, chest pain, and fever.

Hot tub rash

“Hot tub rash” is another name for Pseudomonas folliculitis, a skin condition caused by a germ called Pseudomonas aeruginosa. It’s most common in hot tubs that aren’t clean or well maintained, and it tends to affect areas of the body where your swimsuit is against your skin.

Symptoms of hot tub rash usually develop within a few days of exposure. You may experience an itchy or bumpy rash, along with blisters around your hair follicles. Most cases of hot tub rash are mild and go away on their own without medical attention.

Rise in body temperature

To prevent burns and overheating, hot tub temperatures should not exceed 104°F (40°C).

Hot tubs are also considered unsafe if you are pregnant because of the rise in body temperature.

Symptoms of hot tub sickness can vary depending on the exact underlying infection. Aside from diarrhea, you might experience:

  • abdominal pain
  • gas
  • greasy, smelly stools
  • nausea
  • vomiting
  • fever
  • chills
  • headache
  • muscle aches
  • skin rashes
  • shortness of breath

Most cases of acute diarrhea tend to resolve on their own with home care within 4 days. However, you should seek medical help if symptoms last longer than 2 days, or you’re having more than six loose stools per day.

You should also seek immediate care if you have:

  • blood or pus in your stools
  • fever of 102°F (39°C) or higher
  • frequent vomiting
  • severe abdominal pain
  • dehydration

Additionally, you should call a doctor right away or seek immediate care if you experience possible symptoms of Legionella exposure and you’ve used a hot tub within the last 2 weeks.

If you’re using a hot tub shared with others or in a public space, the only way you may be able to prevent related illnesses is to avoid getting water in your nose and mouth.

However, there are steps you can take to prevent passing illnesses to others if you use a hot tub. These include staying out of the hot tub if you have diarrhea and taking a 1-minute shower before getting in the water to help rinse potential germs off your body.

If you’re using your own hot tub at home, be sure the chlorine and bromine levels are at appropriate levels by using testing strips. Any strong chemical odors could indicate a problem with the water. Ideally, the water should contain the following levels:

  • Bromine: 4 to 8 parts per million
  • Chlorine: 3 to 10 parts per million
  • pH: 7.0 to 7.8

The Centers for Disease Control and Prevention (CDC) doesn’t recommend hot tubs for children younger than 5 years old. If any children do use the hot tub, be sure to take them on frequent bathroom breaks to help prevent accidents in the water.

You can help protect yourself against illnesses by not swallowing hot tub water. If you do happen to be sick, call a doctor if your symptoms worsen, and be sure to stay out of the hot tub while you recover.